What is the primary avatar?
misc.transport.road FAQ Part 2 of 4
Hello Guest		   
  • Login
• Register…
• Start blog		   • Who, Where, When
• What is interesting here?
• Duels		   • Polls
• Avatars
• Interests		   • Cities and Countries
• Random blog
• Users search		   • Search
• Games
• Tests
• CarGuru		   • Ñîîáùåñòâà
• Talxy Chat
• Horoscope
• Online		  
Register!
CarGuru > Driving > misc.transport.road FAQ Part 2 of 4 3 August 2006 04:10:47
  Recent blog posts: 
95 mirage
I have a 95 mirage and this is the second time the injector in number 3 cylinder has gone bad. Anything…

1988 Ford F-150 Truck
I would like to remove the pollution control system from my 1988 F-150, 4.9L I6 300 4x4. Can anyone…

my 99 M chrysler has started to…
my 99 M chrysler has started to cool and then starts to give off heat in the ac vents and then cool…

dodge 2000 intrepid
bought this car right off the show room floor in Bartow fl to this date I have not had any work done on…

starting issue, 2002 dodge…
My 2002 Dodge Caravan wouldn't crank. I tested some things, replaced the battery. After installing the…

;-)
;-)­

stereo pin
I put a new battery in my girl friends 94 900 and it wants a code for the radio. There is nothing in the…

Coolant temp on Saturn Sky
I just purchased a 2007 Saturn Sky Redline. As I was driving yesterday I happen to have the info set on…

Saturn Sky Red Line
I just purchased a 2007 Saturn Sky Redline. I noticed will driving yesterday that when I turned on the…

Que pour la place trange
Que pour la place trange

  They have birthday today: 
Esther
  Forums:   
    topic feeds

• CarGuru  all topics, blogs and comments

• Driving

• Formula-1

• Indycar

• Nascar

• Other sport

• Technology

• 4 x 4

• Volkswagen

• Mercedes

• Acura

• Alfa-romeo

• Audi

• BMW

• Chrysler

• Dodge

• Ford

• General Motors

• Jeep Willys

• Honda

• Hyundai

• Mazda

• Nissan

• Peugeot

• Pontiac

• Porsche

• Saab

• Saturn

• Toyota

• Volvo

• Buy / Sell

• Open discussion

• Anonymous
  Discuss: 
Re: Road test - DMV is cracked
On 28 Oct 2005 02:52:39 -0700, littleboyblu87@yaho­o.com wrote: What state is that? In TX, I…

Happy New Year!
Hi Viatologists, The Worldwide Highway Library would like to wish all viatologists a warm, happy New…

ETHANOL: HOW BRAZIL BEATS THE…
I guess America is so involved in fighting terrorism that forgets to prepare herself for a fuel crisis…
  Recent forum topics: 
2005 nissan sentra
I removed the radio in my 2005 sentra to replace the tempature control knob and the radio won't turn on…

Brake Lights won't work
brake lights on 1996 Grand Am won't work. Fuse and lights are fine. Suggestions?

honda civic 87 model problem
i would like some information on why my honda civic wont start at times after its hot when running it…

mazda premacy glowplug lights…
i have a mazda premacy 2litre diesel . have a problem at the moment ,glowplug light flashing with loss…
  Recent forum comments:
RE: Ask How To Replace Headlight…
how do I release the locking ring on the headlamp bulb in a 99 dodge ram 2500?

RE: Re: Transmission shudder when…
who are you speaking to

RE: Re: Transmission shudder when…
I can feel something like a kick when I first hit the gas pedal when I take off.

RE: stuck hatchback
on the rear gate that is

RE: stuck hatchback
just my latch is stuck and the door wont close on my 2000 sub outback limited

RE: 1999 Chrysler T&C - Speed…
I am reading all of this and am amazed at how bad I am getting ripped off by my Chrysler dealership....4…

RE: How to duplicate Navtech CD’s
where can i buy nav cd's for a 2003 s class mercedes also the latest version for a 2005 sl?

RE: Heating problem in 1988 Honda…
well thats no always true!!! my husband replaced the thermostat/thermome­ter..... and the water…

RE: Mitsubishi Diamante ECU faults…
how did you read the codes

RE: 98 Dodge Grand Caravan Problems
I had the same problem with the instrument panel, after about a months worth of greif, and dollars…
  Ìîäåðàòîð:
 Administrator

misc.transport.road FAQ Part 2 of 4

Marc Fannin 11 March 2005 02:13:30
 Here are Sections 5 and 6.

The FAQ in its entirety is at http://www.roadfan.­com/mtrfaq.Âhtml (c.
200KB)

___________________­____________________­____________________­_____________
Marc Fannin|musxf579@ken­t.edu or @hotmail.com| http://www.roadfan.­com/


-------------------­--


5 Websites

Links to road websites are available at
http://dmoz.org/Rec­reation/Roads_and_Hi­ghways/ (alternate URL:
http://roadlinks.cj­b.net/ ),
http://www.aboutvia­.com/ (alternate URL:
http://www.ugcs.cal­tech.edu/~jlin/links­/ ),
http://www.aaroads.­com/kick-off/highway­.html , and
http://www.cahighwa­ys.org/othlinks.html­ .
(All of these are listed at
http://dmoz.org/Rec­reation/Roads_and_Hi­ghways/Directories/ .)

A list of roadgeeks by location is at
http://www.roadfan.­com/roadfan.html .

May 24, 2004


-------------------­--------------------­--------------------­--------------------­-

6 The Interstate Highway System

The Interstate Highway System (or, more formally, the Dwight D.
Eisenhower National System of Interstate and Defense Highways) is a
system of divided controlled access highways present in every state as
well as DC and PR. It has more than 45,000 miles to its credit. A
complete list is found at http://www.ihoz.com­/interstates.html (1 and 2
digit) and http://www.kurumi.c­om/roads/3di/ (3 digit), as well as at
http://www.intersta­te-guide.com/ . Information on planned Interstates
and Interstate extensions can be found at
http://www.aaroads.­com/high-priority/ and
http://www.intersta­te-guide.com/future.­html . FHWA's overview of the
system is at http://www.fhwa.dot­.gov/programadmin/in­terstate.html , a
route log is at http://www.fhwa.dot­.gov/reports/routefi­nder/ , and some
history is located throughout
http://www.fhwa.dot­.gov/infrastructure/­history.htm . AASHTO's
Interstate policy is at http://members.aol.­com/rcmoeur/inpolicy­.html .
This policy states among other items that Interstates and U.S. Highways
with the same number should not exist in the same state, although US 24
and I-24 both exist in IL, and US 80 and I-80 briefly existed in CA
until the former was truncated outside the state (both instances
presumedly overlooked due to the distance between), and three proposed
Interstate extensions are planned to exist in states with the
corresponding U.S. route (49 in AR, 69 in TX, 74 in NC - on current
signage for the latter's pairing with US 74, "FUTURE" replaces
"INTERSTATE" on the I-74 shields). Also, there are single-state
Interstates (see 6.12) - the name "Interstate" refers to the system as
a whole and not to any individual numbered route. A ranking subject to
interpretation of 2-digit Interstates by importance is located at
http://www.kurumi.c­om/roads/rank2di.htm­l . For business route
information see 3.2. Dec 4, 2004

6.1 Interstate History

See also Section 17.

6.1.1

Q: How did the Interstate Highway System come to be?

A: In 1944, Congress authorized construction of an interstate
expressway system connecting major cities and industrial centers. No
money was involved in the bill. The project never took off until the
awarding of the first contract for I-70 in Missouri, in 1956. North
Dakota was the first state to complete its Interstates. More
information is available at
http://www.tfhrc.go­v/pubrds/summer96/p9­6su10.htm and
http://eisenhower.a­rchives.gov/dl/Inter­stateHighways/Inters­tateHighwaysdocument­s.html
. Jul 10, 2003

6.1.2

Q: What was the first stretch of Interstate to open?

A: The first stretch of Interstate opened under the 1944 Congress act
was I-70 in Kansas, which opened in 1957. More information is at
http://www.tfhrc.go­v/pubrds/summer96/p9­6su18.htm 2000-08-17 15:29:33

6.1.3

Q: What were the original plans for Interstates?

A: The Interstate System's original plans are detailed in a publication
called General location of national system of interstate highways,
including all additional routes at urban areas designated in September,
1955, commonly known as the "Yellow Book". Go to
http://www.roadfan.­com/intreg.html#yell­owbk for much more information
including maps. Feb 25, 2002

6.2 Interstate Numbering

There's a very strict plan for numbering Interstate routes. The one and
two-digit routes are the mainlines, with the even numbered routes going
east-west, and the odd routes going north-south. The even routes'
numbers increase as you go north, with the odd Interstate roads
increasing to the east. The major routes end in 0 or 5. As for
three-digit interstates, those that both start and end at a 2-digit
route get an even first digit, while those not connected to the
Interstate system at their end or ends have an odd first digit.
Exceptions to this occur usually when a state has depleted its
respective choices for 3-digit Interstates. If a 3-digit Interstate has
another 3-digit Interstate branching from it (a "grandchild"), then the
numbering for the second-generation highway is the same as for the
first-generation one. In the field are I-105 CA, I-235 KS, I-444 OK,
I-370 MD, I-175/375 FL, I-278/478/678/878 NJ/NY, I-579 PA,
I-280/380/980 CA, I-190 MA, I-590/990 NY, I-495 NY, I-695 DC, and I-795
MD (each intersects with another 3di with a common "root" but not with
its 2di parent). I-195 NJ also used to be one but it now intersects
I-95 directly. For more on numbering see the FHWA site at
http://www.fhwa.dot­.gov/programadmin/in­terstate.html#Inters­tate_Numbering
. Apr 14, 2004

6.2.1 Letter Suffixes

6.2.1.1

Q: What happened to letter extensions on Interstate highways?

A: AASHTO eliminated them in 1980 and told state DOTs to think of other
numbers. Two still remain on I-35. I-15E in California stayed until
1983 (see 6.2.1.3). Jan 18, 2002

6.2.1.2

Q: Why does I-35 split in Dallas and Minneapolis?

A: As stated in the previous question, some Interstates once carried
letter suffixes. All but three were changed in 1980, and one of those
(I-15E in CA) was gone by 1983. The remaining two are the I-35 splits
in Dallas and Minneapolis, which remain because there was no consensus
on what the new numbers would be. The smaller cities, St. Paul and Fort
Worth, did not want their Interstate highways "demoted" to 3di's. Jul
9, 2003

6.2.1.3

Q: What are/were all the suffixed interstates?

A:

Actually existed

I-5W (CA) -- I-505, I-80, I-580, I-205 (see
http://www.cahighwa­ys.org/001-008.html#­005 for details)
I-15E (CA) -- I-215 (see http://www.cahighwa­ys.org/009-016.html#­015 ,
section 2, for details)
I-15W (ID) -- western I-86
I-24W (MO/TN) -- I-155 and US 412
I-35W/I-35E still exists in TX and MN (see 6.2.1.2)
I-35W (KS) -- I-135
I-59B (AL) -- I-459 (Note: "59B" was chosen through a system of
placeholder numbers using "A", "B", etc., as opposed to "B" meaning
"bypass")
I-70N/I-70S (MD) -- I-70/I-270
I-70S (PA) -- I-70 between I-79 and I-76
I-75E (FL) -- I-75 between I-275 termini
I-80N (OR/ID/UT) -- western I-84
I-80N (IA) -- I-680 east of I-29
I-80N (OH) -- I-80/90, I-90, I-490, I-480, and OH 14 between US 250
near Norwalk and I-76 near Ravenna
I-80S (CO/NE) -- western I-76
I-80S (OH/PA/NJ) at first used today's I-76 in OH and PA and I-276 in
PA; later it was rerouted on today's I-76 and I-676 through
Philadelphia and Camden rather than around; and later it was truncated
at today's I-376 when I-76 was created along today's I-376 and the PA
Turnpike
(See http://www.roadfan.­com/ohiomaps.html ,
http://www.pahighwa­ys.com/interstates/p­di.html#I80S , and
http://www.fhwa.dot­.gov/infrastructure/­i76.htm for details on the
OH/PA/NJ I-80N/I-80 and I-80/I-80S)
I-81E (PA) -- I-380
I-180N (ID) -- I-184 in Boise; all other spurs of suffixed 2dis were
non-suffixed


Planned but never signed

The sources for these are the 1957 and 1958 maps on
http://www.roadfan.­com/5758int.html -- see 6.1.3 for more details

I-5E (CA) -- I-5 between I-5W termini (see above)
I-80N (PA/NJ) -- I-78
I-80S (PA) -- I-76 east of Harrisburg
I-81S (PA) -- I-81E (see above)
I-82N (ID) -- I-15W (see above)
I-82S (ID/UT) -- I-80N between I-15W (see above) and I-15
I-90N (NY) -- I-190
I-94N (MI) -- I-196 (now I-96 west of Grand Rapids)
I-95E (RI/MA) -- I-195 (pre-Interstate plans called it US 6)

Dec 4, 2004

ber?

A: This has been one of the most contentious questions or topics in the
newsgroup. Unlike other interstate highways, which have their numbers
assigned by AASHTO, I-99's number was assigned in a piece of
appropriations legislation sponsored by former Rep. Bud Shuster
(R-Pa.), through whose district the highway ran.

Many of the regulars on m.t.r take issue with this highway designation
because:

1) Its number was written into law, as described above;

2) Its number is out of place--a highway designated as I-99 should run
right along the Atlantic coast; and

3) From its length (under 70 miles), location (in an area where all the
available 2di designations are already being used), route (basically, a
spur from I-76 to the Altoona/State College area, at least until it
connects to I-80), and the fact that it doesn't come close to any
interstate other than I-76, an odd 3di designation (such as I-576)
would be more appropriate.

As a side note, for now I-99 also has the distinction of being the only
2 digit interstate that does not have a direct interchange with any
other interstate.

More information is available at
http://www.pahighwa­ys.com/interstates/I­99.html . Oct 3, 2004

6.2.3

Q: What is I-238?

A: Interstate 238 is a 2-mile freeway on the east side of San Francisco
Bay, California. It is not numbered according to the regular Interstate
numbering conventions; rather, it was an extension of CA 238. There is
no I-38. More information is at http://www.gbcnet.c­om/roads/I-238/ .
May 28, 2002

6.2.4

Q: Why are there two Interstates 76, 84, 86 and 88?

A: All duplicates but 86 arose around the time when most letter
suffixes on Interstates were removed, though not all replaced a
suffixed Interstate designation. Eastern I-86 (see 6.3.6) was recently
added because there were no other choices that would fit. At one time,
an eastern I-86 existed from Hartford, CT to I-90 in MA; this is now
part of I-84 (see http://www.kurumi.c­om/roads/ct/i86.html­ ). There were
also two I-39s, but I-39 is now signed along I-90 between the two
sections (see http://www.intersta­te-guide.com/i-039.h­tml ). May 13,
2003

6.2.5

Q: Which 3di spurs go both directions from a parent?

A: I-305 CA (hidden), I-516 GA, I-540 AR (small overlap with I-40),
I-170 MO (crosses I-70, ends at I-270), I-580 CA (small overlap with
I-80), I-181 TN (to be replaced by I-26), I-390 NY (crosses I-90, ends
at I-490), I-394 MN (crosses I-94, ends at I-494), I-595 FL; future:
I-710 CA, I-355 IL, I-195 NJ Jan 29, 2004

6.3 Oddities

6.3.1

Q: What happens to I-95 in NJ?

A: The short explaination is the "NIMBY factor". Residents of the
Princeton and New Brunswick, NJ, areas managed to kill a section of
I-95 through their towns in the early 1980s; the NJ Turnpike also
opposed it as it would provide an alternate to the toll road. There has
been a gap ever since. On the NJ Turnpike, the I-95 signs disappear.
There is a plan to build an interchange connecting the existing I-95
with the PA Turnpike northeast of Philadelphia, where they currently
cross but do not have an interchange. The new routing would follow the
PA Turnpike connector from the NJ Turnpike across the Delaware River to
the new interchange, where it would resume its old route. This
interchange should be complete around 2008. More information is
available at http://www.njfreewa­ys.com/Interstate_95­_Gap.html ,
http://www.nycroads­.com/roads/I-95_NJ/ , and
http://www.paturnpi­ke.com/i95/ . This will complete the gap between New
York City and Philadelphia, but will not provide easy access to I-287
from Philadelphia for bypassing New York City as original I-95 would
have.
Some propose rerouting I-95 on the NJ Turnpike all the way to the
Delaware Memorial Bridge and I-295; this is how most through traffic
goes anyway. Many people have a problem with this because it would
bypass Philadelphia. Sep 30, 2004

6.3.1.1

Q: Are I-95's exit numbers between I-80 and NY an extension of I-80's?

A: No. Those numbers are based on the original mileage of I-95 in NJ
including the unbuilt portion mentioned above in 6.3.1 (see the
relevant section of http://www.nycroads­.com/roads/I-95_NJ/ ). Sep 30,
2004

6.3.2

Q: Why do some Interstates, such as I-180 in WY, have traffic lights or
at-grade intersections?

A: Usually Interstates are not allowed to have any cross traffic. In
fact at-grade intersections have kept the new I-86 in New York from
extending further east. But in these cases, AASHTO granted variances
because there was no other reasonable way to build them.
Wyoming I-180 is the only Interstate with no freeway portions. There
are three stoplights. Why was it commissioned in the first place? The
state of Wyoming wanted an Interstate serving downtown Cheyenne. It was
to be freeway, but that idea was rejected. More information is at
http://www.rockymou­ntainroads.com/wyomi­ng/i-180.html
I-676 in Philadelphia, PA has some traffic lights between the Vine St
Expressway and the Ben Franklin Bridge. Construction of a freeway
connection would impact several historic landmarks. There is some doubt
among roadgeeks as to whether I-676 actually goes this way; the
official PennDOT maps label the freeway connection to I-95 as 0676 and
put US 30 on the Ben Franklin Bridge. There is an I-676 shield on the
county map, but shields reflect actual signage, not internal
designations (as the 0676 does). NJDOT however takes I-676 over the
bridge officially and in signage. (See
http://www.pahighwa­ys.com/interstates/I­676.html)
I-78 in Jersey City, NJ runs along a one-way pair of surface streets
between the end of the Turnpike Extension and the Holland Tunnel. I-78
ends just across the border in Manhattan, New York City, so it could be
truncated, but hasn't been. NJ 139 also runs along those streets, as if
NJDOT were prepared for truncation. FHWA, NJDOT, and NYSDOT all
officially refer to these last few miles as I-78. (See also 12.2 )
I-70 in Breezewood, PA is the most famous of these. It runs along a
short section of US 30 lined with businesses between the north-south
free portion of I-70 and the Turnpike connection. It would be fairly
easy to construct direct ramps, but the businesses have been successful
in blocking them. Some think the influential congressman Bud Shuster
has helped block the ramps. (See 3.1 above)
I-585 in Spartanburg, SC is signed past the end of the freeway past
several traffic lights. It is unknown why; the road is also US 176.
(See 6.3.9)
I-690 at the NY State Fairgrounds in Syracuse has a pedestrian crossing
that only functions during the NY State Fair. Because this is only in
operation for a small period of time, it is not worth it to build an
overpass.
I-8, I-10 and I-17 in AZ, I-40 in NC, I-10 and I-40 in W. TX, and I-40
in NM have some at-grade intersections for forest, farm, and ranch
access (see http://www.arizonar­oads.com/wrong/). Most of these highways
were built directly over a pre-existing rural two-lane road, so this is
the only access for many of these properties. Interchanges would not be
worth the expense due to the extremely low traffic which these
intersecting roads carry (some in fact are private).
AK Interstates have signals, but that is because those Interstate
designations are "hidden" along state highways which are usually
surface roads with at-grade intersections (see Question 6.3.8 ).

Several other interstates end at traffic lights, but this is perfectly
OK as long as this is not a 3di's only connection to its parent or an
even 3di's only connection to another interstate at one end.
One example of this that is often brought up is I-587 is Kingston, NY;
this connects to the I-87 ramp via a traffic circle. However, a traffic
circle is somewhat up to standards; there is no cross traffic.
In fact there is a case of a 3DI not meeting its parent; the
abovementioned I-585 in Spartanburg, SC ends at Business Loop I-85,
which is the old I-85 (and is a freeway, but not up to full interstate
standards). It continues to I-85 (bypass) as 4 lane US 176, which is
due for upgrades soon. (See 6.3.9)
I-65 in NW IN formerly had a traffic light installed in 1980 at the IN
Toll Road (I-90) connection at the north end (map at
http://terraserver-­usa.com/image.aspx?t­=4&s=11&z=16&x=1186&­y=11510&w=3
); this was considered by INDOT to be mainline I-65 (
http://www.in.gov/d­ot/div/technology/in­terchanges/I65/is262­.pdf - note
that this diagram shows the rail crossing just north of the signalized
intersection as active; it actually was abandoned by the time I-65 was
extended northward to US-12/20) but was not really the same case of a
traffic light on an Interstate as other examples because the section
north of this signal functioned more like a ramp pair, and was probably
considered one by AASHTO. This has been replaced by conventional
grade-separated freeway ramps.
I-291 in Springfield, MA, has an access point at I-90/MA Turnpike
similar to the former I-65/I-90 junction cited above, albeit with a
more simple design (
http://terraserver-­usa.com/image.aspx?T­=4&S=10&Z=18&X=3514&­Y=23353&W=3
).

Several tunnels on the system have signals at their portals, either to
stop unwanted vehicles from entering (too tall, too heavy, too wide,
hazardous material carrier) or for traffic capacity control.

Question 6.3.7 deals with drawbridges on Interstates, which have
traffic lights but no cross traffic.

Railroad crossings:
The Interstate highway specifications do not permit railroad grade
crossings. A few did exist before, but all have either been grade
separated or had the tracks removed. However, a number of crossings do
still exist on some non-Interstate highways with controlled access. In
many of these cases, the crossing is classified as "Exempt" by the
particular state, meaning that vehicles normally required to stop at
railroad crossings, such as vehicles carrying hazardous material and
school buses, can continue through without stopping. Instead, all
trains are required to send a flagman to clear the highway traffic
before it may proceed. These crossings are rarely busy railroad
mainlines, as they tend to be lightly-used or even disused industrial
spurs. Exempt crossings are noted with a tab on the advance RxR warning
sign post and/or on the crossbuck post itself (see
http://mutcd.fhwa.d­ot.gov/HTM/2003r1/pa­rt8/part8b.htm#secti­on8B05 ).

Former crossings on Interstates:
I-65 north end in IN (see above). Abandoned, then interchange
reconstructed.
I-87 Adirondack Northway, NY, near the Mohawk River. This line was
apparently already up for abandonment with the now-defunct Interstate
Commerce Commission when the Interstate was being built, so it did not
pay to build an overpass that would be useless in a few years.
I-94 near Ypsilanti, MI. Now abandoned. This same line used to cross US
23 at-grade as well.
I-94 near Albion, MI. Now abandoned.
I-395 in N. VA (Shirley Highway) near Glebe Rd. Crossing dismantled
when the Washington & Old Dominion RR folded. Note that this was while
it had its pre-Interstate designation (VA 350).

Existing crossings on non-Interstate controlled-access highways [* -
Exempt]: US 1, Edison, NJ (Jersey Freeway); US 4 near Rutland, VT; US
12/14/18/151, Madison, WI; US 30/250, Wooster, OH*; US 60, Springfield,
MO; US 63, Columbia, MO; US 151, Beaver Dam, WI; US 151, Waupun, WI; US
301, Rocky Mount, NC; US 322 between Harrisburg and Hershey, PA*; ; OH
7, north of Martins Ferry; Atlantic City-Brigantine Connector, NJ*

Other former grade crossings on major divided highways: US 1, Danvers,
MA; US 3, Billerica, MA; US 4, Portsmouth, NH; US 6, Denver, CO; US
12/14/18/151, Madison, WI (2 others in addition to the current one); US
23 south of Dundee, MI (and others); US 64, Tulsa, OK (2); US 131,
Kalamazoo, MI; MA 2, Concord; NY 17 (Quickway)/future I-86 near
Middletown, NY

Note: The above question refers to Interstate intersections with roads
which carry general traffic and not roadways such as maintenance roads
(intersections between these and freeways are common throughout the
U.S.). Mar 7, 2005

6.3.3

Q: Where was the Embarcadero Freeway and why was it torn down?

A: The Embarcadero Freeway, I-480, would have connected the Bay Bridge
to the Golden Gate Bridge in San Francisco, carrying mostly local
traffic. The first section north from I-80 was built. Most San
Francisco residents hated it because it blocked the view of the
waterfront from the other side. After a 1989 earthquake almost made it
collapse, it was permanently closed and torn down. The same thing
happened to the northern half and most of the upper deck of the Central
Skyway (US 101). Across the Bay in Oakland, part of the Cypress Freeway
(I-880) actually collapsed, killing some motorists. This double decker
freeway was torn down and rebuilt on a new alignment; the old alignment
is now a wide boulevard with a park in the middle.
More information is at http://www.cahighwa­ys.org/371-480.html#­480 and
http://www.kurumi.c­om/roads/3di/i480.ht­ml#480ca . Apr 9, 2004

6.3.4

Q: Why are these I-73 and I-74 signs popping up in North Carolina?

A: Interstate 73 and the 74 extension are specified in the ISTEA
legislation. I-73 will go from Sault Ste. Marie, Michigan to Myrtle
Beach, South Carolina, while the 74 extension will head east from its
present Cincinnati, Ohio terminus to Portsmouth, Ohio and be mostly
multiplexed with 73 south of there. A North Carolina portion south of
Greensboro was already freeway, so they installed signs there. Some
states are reluctant to build the new highway, specifically Ohio. More
information is at http://www.aaroads.­com/high-priority/co­rr05.html
2000-08-11 19:10:26

6.3.5

Q: Why are there freeway loops in Phoenix?

A: The loop freeways are not Interstates because they are funded by a
1/2 cent sales tax paid by county residents, not by Federal money. If
these freeways had waited for inclusion in the Interstate system, they
may have been delayed for years, or never been built at all. More
information is at http://www.arizonar­oads.com/urban/ . Jan 15, 2002

6.3.6 What is the new I-86?

The eastern I-86, the newest 2di, runs from just outside Erie, PA, to
East Corning, NY, along state route 17, the Southern Tier Expressway.
The move was designed to spurt economic development in the Elmira and
Binghamton areas. This part was designated in late 1999; it is planned
to extend east to I-87 at Harriman once the at-grade intersections are
eliminated. More information is at
http://www.aaroads.­com/high-priority/co­rr36.html Apr 8, 2002

6.3.6.1

Q: Does it really dip into Pennsylvania?

A: Yes, it does. Exit 60 (US 220) is entirely in Pennsylvania, and the
dip is complete with "STATE BORDER" signs. However, New York maintains
it. Maps: http://www.empirest­ateroads.com/maps/wa­verly.jpg ,
http://terraserver-­usa.com/image.aspx?S­=12&T=2&X=466&Y=5813­&Z=18&W=2 By
the way, this is not part of I-86 yet. Sep 2, 2003

6.3.7

Q: Where are all the drawbridges on the Interstate system?

A: These all had to get variances from FHWA to be approved into the
interstate system.
I-5, OR/WA (Columbia R) -- see
http://www.bizave.c­om/cgi-bin/photoalbu­m.cgi?photoalbum=pdx­bridges&slidetag=Int­erstate
I-64, VA (Elizabeth R) -- see
http://www.roadstot­hefuture.com/I64_VA_­Desc.html or
http://www.aaroadtr­ips.com/hampton_road­s.html
I-95/495, VA/DC/MD (Potomac R); see
http://www.roadstot­hefuture.com/Woodrow­_Wilson_Bridge.html (this is
planned to be replaced by a higher drawbridge - information at
http://www.wilsonbr­idge.com/ ) See also 12.2
I-110, MS (Back Bay) -- see http://southeastroa­ds.com/i-110_ms.html­
I-264, VA (Elizabeth R) -- see
http://www.roadstot­hefuture.com/I264_VA­_Desc.html or
http://www.aaroadtr­ips.com/hampton_road­s.html
I-278, NY (Bronx R) -- see http://www.nycroads­.com/roads/bruckner/­
I-280, NJ (Passaic R) -- see http://www.nycroads­.com/roads/I-280_NJ/­
I-280, OH (Maumee R) -- see http://www.roadfan.­com/toledo.html#prop­
(this is being replaced by a fixed span - information at
http://www.lookupto­ledo.org/)
I-695, MD (Curtis Cr) -- see
http://www.roadstot­hefuture.com/Balt_Ou­ter_Harbor.html

Former drawbridges replaced by fixed spans:
I-75, MI (Saginaw R) -- see
http://www.michigan­highways.org/indepth­/zilwaukee.html
I-95, FL (St. Johns R) -- see
http://www.dot.stat­e.fl.us/structures/b­otm/fullerwarren/ful­lerwarren.htm
I-95, NY (Hutchinson R) -- see
http://www.nycroads­.com/roads/new-engla­nd/
I-395 (originally I-95), DC/VA (Potomac R) -- see
http://www.roadstot­hefuture.com/14th_St­reet_Bridge.html (bridge is
still a drawbridge but has been rendered inoperable)
Dec 4, 2004

6.3.8


Q: Why are there Interstate highways in Hawaii? Are there plans for
Interstates in Alaska or Puerto Rico? Are there any freeways in Alaska
or Puerto Rico?

A: The Hxx Interstates were approved by AASHTO when Hawaii became a
state in 1959 to allow Hawaii to have Interstates (see
http://www.fhwa.dot­.gov/infrastructure/­hawaii.htm and
http://www.hawaiihi­ghways.com/FAQs-page­4.htm#why-Interstate­s ). Even
though Alaska and Hawaii do not connect directly to other states, their
highways fall into the same system as those in the other 48 states, so
while "Interstate" can't be literal, the name is there for consistency.
Alaska and Puerto Rico officially have Axx and PRxx routes,
respectively, but these are unsigned and, in Alaska's case at least,
generally not up to Interstate standards. In 1959, when Alaska became a
state, they asked for funding for fully standard Interstates on the
current corridors plus others, including one to Nome. This was
rejected. In 1981, FHWA added current routes A1-A4 to the Interstate
system as 2 lane rural arterials. The only Alaska Interstate routes
that have been upgraded to freeway are AK 1 (A1) east of downtown
Anchorage to just short of the AK 3 (Interstate A4) junction in Palmer,
and a few miles of AK 1 (Interstate A3) south of downtown Anchorage.
Puerto Rico has many rural and urban freeways (autopistas); most of the
rural freeways are tolled. The AK/HI/PR Interstates do not have an "I-"
preceding them in their abbreviations.
Here is a list of the Ax routes:

A1 follows AK 2 from the Canadian border to Tok Junction and then AK 1
to Anchorage.
A2 follows AK 2 from Tok Junction (AK 1) to Fairbanks.
A3 follows AK 1 from Anchorage to Soldotna.
A4 follows AK 3 from Palmer (AK 1) to Fairbanks.

Aug 17, 2004

6.3.9

Q: What's up with I-585 in Spartanburg, SC?

A: When the I-85 bypass around Spartanburg was built, old I-85 became
BUSINESS I-85. I-585 originally ended at I-85 like it should, but since
new I-85 was built it has not touched I-85.
Another oddity on I-585 is the fact that it is signed for several
blocks past the freeway end in downtown Spartanburg.
In other words, I-585 doesn't extend far enough to I-85 and extends too
far on the other end. See http://www.kurumi.c­om/roads/3di/i585.ht­ml and
http://www.intersta­te-guide.com/i-585_s­c.html . May 28, 2003

6.3.10

Q: Why is the Chicago Skyway no longer I-90?

A: In late 1999, Chicago added a TO banner to all the I-90 reassurance
markers on the city-maintained Skyway. Apparently the city was looking
at old records and realized it was never technically approved as an
interstate (see
http://groups-beta.­google.com/group/mis­c.transport.road/msg­/2044938ffca6c8b4
, message ID n9jig-2008991217310­001@chi-pm4-1a-40.th­eramp.net ).
Another strange fact about the Skyway is that it was built as a 10 mile
toll bridge. Illinois law at the time prohibited non-bridge toll roads,
so Chicago had to get it approved as a toll bridge over the Calumet
River.
In early March 2004 a plan to privatize the Skyway was proposed; this
plan was put into action in mid-October 2004. ("For Sale: Chicago
Skyway", Chicago Sun-Times, March 2, 2004; "Overseas investors to lease
Skyway from city", Chicago Tribune, October 15, 2004)
The Skyway has a McDonald's restaurant in the median by the toll plaza.
Related: http://www.n9jig.co­m/tollways.html Oct 21, 2004

6.3.11

Q: Why does I-180 in IL exist?

A: I-180 serves the town of Hennepin, population 707 (2000 census). It
was built to serve LTV steel, a major defense contractor. In the future
it may be extended south to Peoria, but it currently has almost no
traffic. See http://www.kurumi.c­om/roads/3di/i180.ht­ml#180il ,
http://www.n9jig.co­m/gallery/expw.html , and
http://www.intersta­te-guide.com/i-180_i­l.html . May 28, 2003

6.3.12

Q: What happened to I-265 in Nashville?

A: In late 2000, I-65 was rerouted along the former I-265, which
existed between I-24 and I-40 northwest of downtown, to relieve traffic
on the former I-40/65 multiplex (now I-40 between I-65 and I-24). See
http://www.kurumi.c­om/roads/3di/ix65.ht­ml#265tn and
http://www.intersta­te-guide.com/i-265_t­n.html . May 28, 2003

6.3.13

Q: Are Kentucky's parkways built to Interstate standards?

A: No, according to Carl Dixon, Branch Manager, Division of Planning,
Kentucky Transportation Cabinet. Each of Kentucky's parkways would
require work to reach the standards defined for Interstates. Work that
would be required depends on the parkway; however, the work would
"include more lanes (e.g., the Daniel Boone Parkway), wider median
widths, wider shoulders, reduced grades, smoother curves, improved
interchanges, and possibly several other design details". The Parkways,
however, do allow trucks. The "Parkway" designation stems from the fact
that that's what Kentucky called its toll highways (not all of these
are tolled anymore). I-66 is planned to run along the Cumberland
Parkway and possibly the Boone, Natcher, and Western Kentucky Parkways,
and I-69 is planned to run along the Purchase Parkway and possibly the
Pennyrile and Western Kentucky Parkways (see
http://www.kentucky­roads.com/i-66/ and
http://www.kentucky­roads.com/i-69/ ). Jan 28, 2002

6.3.14

Q: Why do I-17's exit numbers start so high?

A: Until the mid-1980s Arizona used a special system for its mileage --
any route which did not enter Arizona from another state used the
mileage of the route where its southern or western end was for its
point of origin rather than zero (e.g.: If Route 2's southern end was
at Route 1 and Route 1's mileage at the Route 1/Route 2 intersection is
Mile 57, then Route 2's lowest-numbered milemarker would be Mile 57).
I-17 is a special case: Its exit numbers are actually those of the
former longer routing of AZ 69, which branched from US 89 at Mile 201,
since I-17 and AZ 69 were paired early on. AZ 69 has been truncated
since I-17's exits were numbered (see
http://www.arizonar­oads.com/arizona/az6­9.htm ). I-17's exit numbers are
not related to those of I-19 (see 10.3). Feb 20, 2002

6.3.15

Q: What's with the I-465 spur northwest of Indianapolis? What is it
designated?

A: I-865, the east-west I-465 spur which connects I-65 to I-465
northwest of Indianapolis, exists partly because the I-65/I-465
interchange farther south lacks ramps between the north and northwest
(it also has no ramps between the south and southeast). It was formerly
signed as I-465 East eastbound and I-65 North westbound (the I-65/I-465
spur interchange also lacks connections, between the southeast and
east) and was simply considered another part of I-465. It was
renumbered to I-865 in April 2002 and signage was changed beginning in
May 2002. Why it is now called I-865 is thoroughly explained in an
Indiana DOT press release (see
http://www.in.gov/s­erv/presscal?PF=dot&­Clist=6&Elist=52862 ). The spur
also carries US 52, which, while not signposted along most of I-465
(see 3.9.1), is in fact signed along the length of the spur. The
milemarkers on this spur used to start at 900 before it was renumbered.
See also http://www.kurumi.c­om/roads/3di/ix65.ht­ml#465in . Jun 11, 2002

6.3.16

Q: Has there been a proposal to extend eastern I-76 eastward?

A: Not officially. Many laypeople have proposed this extension, which
entails the freeway portion of NJ 42 plus most or all of the Atlantic
City Expressway, but this has not been considered officially due to a
combination of sub-Interstate features, potential confusion, and
disinterest (see http://groups.googl­e.com/groups?th=a239­757550d54849 ).
Oct 16, 2003

6.4

Q: Why do people want I-69 extended?

A: The I-69 extension was proposed by businessmen in the early 1990s to
stimulate international trade between Canada, Mexico and the United
States. It would run from Port Huron, Michigan to Brownsville, Texas.
It currently runs from Port Huron to Indianapolis. In Indiana, it was
decided that I-69 will run along a new alignment from Indianapolis to
Evansville (it will probably multiplex with I-465 around Indianapolis)
rather than along I-70, a new southeast bypass of Terre Haute, and an
upgraded US 41. More information is at
http://www.aaroads.­com/high-priority/co­rr18.html ,
http://www.i69info.­com/ , and
http://dmoz.org/Rec­reation/Roads_and_Hi­ghways/Interstate_69­/ . Jul 9,
2003

6.5

Q: What's this I hear about a new Interstate marker?

A: This is a hoax. Basically the rumor was that AASHTO plans to
implement a new shield design by 2007 or earlier. It was a circle in a
square, considered ugly by most.

6.6

Q: Is one mile of each five in the Interstate system required to be
able to act as an emergency landing strip for aircraft?

A: No. See http://www.tfhrc.go­v/pubrds/mayjun00/on­emileinfive.htm
(official) and http://www.snopes.c­om/autos/law/airstri­p.asp . It was
considered briefly ( http://www.fhwa.dot­.gov/infrastructure/­turner.htm
) but never adopted officially. There are unusually-built overpasses
(truss structure) on a straight section of I-75 near the former
Kincheloe Air Force Base (now Chippewa County International Airport) in
the Upper Peninsula of Michigan, leading to speculation that the
Michigan State Highway Department did build I-75 here to accomodate
aircraft. This is purely speculation, however, with no conclusive proof
so far.

Conversely, there was a Cold-War bunker built under I-5 in Seattle, at
the Ravenna Boulevard overpass, by the state of Washington in the early
1960s (see http://www.historyl­ink.org/output.CFM?f­ile_ID=3705 ). Nov 6,
2003

a system in which truck drivers may use a transponder to bypass weigh
stations. For more information go to http://www.prepass.­com/ . Jan 22,
2002

6.8

Q: What is the largest city without an Interstate?

A: It is the consensus of m.t.r that Fresno, CA (2000 pop. 427,652), is
the most populous city in the U.S. without an Interstate within its
boundaries. The closest it has to an Interstate is CA 99, old US 99
(see 7.4.2). (Mesa, AZ, is expected to pass Fresno in population by the
2010 Census - it only has the US 60 freeway and part of the Phoenix
loop system - see 6.3.5 ). The largest cities with only one Interstate
are Austin, TX (2000 pop. 656,562), with I-35, and Colorado Springs, CO
(2000 pop. 360,890), with I-25. El Paso, TX (2000 pop. 563,662) has
only one signposted interstate, I-10, but also has "hidden" I-110 (see
http://www.kurumi.c­om/roads/3di/i110.ht­ml#110tx ). Oct 21, 2004

6.9 Interstate Standards

Interstates have higher standards than basic freeways. While freeways
require grade separation and interchanges in place of at-grade
intersections, Interstates also require, at minimum, 12' wide lanes, 6'
wide shoulders (4' paved - if there are three or more lanes, the left
shoulder should be 12', 10' of it paved), 36' medians in rural areas
and 10' medians in urban or mountainous areas, a design speed of 60 mph
in urban areas and 70 mph in rural areas (with speeds as low as 50 mph
in rugged terrain), acceleration and deceleration lane length to the
current standards of AASHTO (see 4.2), a maximum 6% grade and adequate
right-of-way. (1' equals about 0.30 meter, 1 mile equals about 1.61
kilometers) Exceptions can be granted (such as for the 8% grade on
I-24/US 64 Westbound over Monteagle Mountain, TN, the steepest on the
system - see also Question 12.6), but usually only are for pre-existing
older highways. For more information, see AASHTO's publication DS-4, A
Policy on Design Standards - Interstate System, available here on their
website. See 3.13 for tolls on Interstates.
Many non-Interstates are also built to Interstate standards. Respective
states can request that AASHTO include them in the system if the need
to do so exists (examples: http://www.kurumi.c­om/roads/3di/1970req­.html
). Feb 1, 2005

6.10

Q: Where is the longest stretch between services on an Interstate?

A: Eastern Utah, on I-70 between Green River and Salina (104 miles) --
see http://members.aol.­com/utahhwys/rte070.­htm . Jun 13, 2002

6.10.1

Q: Where is the longest stretch between other Interstates on an
Interstate?

A:
Between Interstates of any type: I-80 in NV/UT, unsigned I-580 to I-215
(511 miles)
Between signposted Interstates: I-80 in CA/NV/UT, I-5 to I-215 (647
miles)
Between 2di's: I-80 in CA/NV/UT, I-5 to I-15 (650 miles)
Mar 24, 2004

6.11 Tunnels

A compilation of Interstate (and other) tunnels and their locations is
at
http://groups-beta.­google.com/group/mis­c.transport.road/bro­wse_thread/thread/79­22cbdaff588381
Feb 1, 2005

6.12 Intrastate Interstates

As mentioned in the intro to this section, individual Interstates may
be found in only one state. Most 3di's are single-state; the single
state 2di's are I-4 (FL), I-12 (LA), I-16 (GA), I-17 (AZ), I-19 (AZ),
I-27 (TX), I-37 (TX), I-43 (WI), I-45 (TX), I-49 (LA), I-73 (NC - see
6.3.4), Western I-86 (ID), I-87 (NY), Both I-88's (IL, NY), I-96 (MI),
I-97 (MD), and I-99 (PA), plus the AK/HI/PR Interstates (see 6.3.8).
The only state which has I-66 is VA, but I-66 also enters DC (see
12.2). Dec 30, 2002

6.13 Multistate 3di's

Multistate three-digit Interstates are 205 (OR/WA), 129 (IA/NE), 435
(KS/MO), 535 (MN/WI), 635 (KS/MO), 155 (MO/TN), 255 (IL/MO), 270
(IL/MO), 470 (OH/WV), 670 (KS/MO), 275 (IN/KY/OH), 676 (NJ/PA), 278
(NJ/NY), 280 (IL/IA), 480 (IA/NE), 680 (IA/NE), 684 (CT/NY), 287
(NJ/NY), 195 (MA/RI), 295 (DC/MD), 295 (MA/RI), 295 (DE/NJ), 395
(CT/MA), 395 (DC/VA), and 495 (DC/MD/VA).

The only existing 3di in three states, the most on any single 3di, is
the IN/KY/OH 275, though the MD/VA 495 also enters DC briefly (see 12.2
), and the DE/NJ 295 is proposed to enter PA. The 265's in IN and KY
may one day connect and be one continuous highway. In addition to the
above, there are proposed 175 in KY and TN; 875 in IN, KY, and OH; and
785 in NC and VA. Former 3di's are 495 (NJ/NY, now just NY - see
http://www.kurumi.c­om/roads/3di/i495.ht­ml#495ny ) and 294 (IL/IN, now
just IL - see http://www.roadfan.­com/mtrfaq.ÂÂhtml
(c. 250KB)

___________________­___________Â________­____________________­__Â____________

Marc Fannin|musxf...@ken­t.edu or @hotmail.com| http://www.roadfan.­com/

-------------------­--

5 Websites

Links to road websites are available at
http://dmoz.org/Rec­reation/Roads_and_Hi­ghways/ (alternate URL:
http://roadlinks.cj­b.net/ ),
http://www.aboutvia­.com/ (alternate URL:
http://www.ugcs.cal­tech.edu/~jlin/links­/ ),
http://www.aaroads.­com/kick-off/highway­.html , and
http://www.cahighwa­ys.org/othlinks.html­ .
(All of these are listed at
http://dmoz.org/Rec­reation/Roads_and_Hi­ghways/Directories/ .)

See also the Wikipedia "Road" entry and related subarticles at
http://en.wikipedia­.org/wiki/Roads .

A list of roadgeeks by location is at
http://www.roadfan.­com/roadfan.html .

Apr 3, 2005


-------------------­--------------------­--------------------­--------------------­-

6 The Interstate Highway System

The Interstate Highway System (or, more formally, the Dwight D.
Eisenhower National System of Interstate and Defense Highways) is a
system of divided controlled access highways present in every state as
well as DC and PR. It has more than 45,000 miles to its credit. A
complete list is found at http://www.ihoz.com­/interstates.html (1 and 2
digit) and http://www.kurumi.c­om/roads/3di/ (3 digit), as well as at
http://www.intersta­te-guide.com/ . Information on planned Interstates
and Interstate extensions can be found at
http://www.aaroads.­com/high-priority/ and
http://www.intersta­te-guide.com/future.­html . FHWA's overview of the
system is at http://www.fhwa.dot­.gov/programadmin/in­terstate.html , a
route log is at http://www.fhwa.dot­.gov/reports/routefi­nder/ , and some
history is located throughout
http://www.fhwa.dot­.gov/infrastructure/­history.htm . The U.S. Code of
Federal Regulations lists in Title 23, Appendix A to Subpart A of Part
470, the "Guidance Criteria for Evaluating Requests for Interstate
System Designations Under [Title] 23 [of the] U.S. [Code, now-repealed
Section] 139 (a) and (b)" (for text, see the portion directly after
Section 470.115 in the respective file at
http://www.access.g­po.gov/nara/cfr/wais­idx_04/23cfr470_04.h­tml ).
AASHTO's Interstate policy is at
http://members.aol.­com/rcmoeur/inpolicy­.html . This policy states among
other items that Interstates and U.S. Highways with the same number
should not exist in the same state, although US 24 and I-24 both exist
in IL, and US 80 and I-80 briefly existed in CA until the former was
truncated outside the state (both instances presumedly overlooked due
to the distance between), and three proposed Interstate extensions are
planned to exist in states with the corresponding U.S. route (49 in AR,
69 in TX, 74 in NC - on current signage for the latter's pairing with
US 74, "FUTURE" replaces "INTERSTATE" on the I-74 shields). Also, there
are single-state Interstates (see 6.12) - the name "Interstate" refers
to the system as a whole and not to any individual numbered route. A
ranking subject to interpretation of 2-digit Interstates by importance
is located at http://www.kurumi.c­om/roads/rank2di.htm­l . For business
route information see 3.2. Apr 1, 2005

6.1 Interstate History

See also Section 17.

6.1.1

Q: How did the Interstate Highway System come to be?

A: In 1944, Congress authorized construction of an interstate
expressway system connecting major cities and industrial centers. No
money was involved in the bill. The project never took off until the
awarding of the first contract for I-70 in Missouri, in 1956. North
Dakota was the first state to complete its Interstates. More
information is available at
http://www.tfhrc.go­v/pubrds/summer96/p9­6su10.htm and
http://eisenhower.a­rchives.gov/dl/Inter­stateHighways/Inters­tateHighwaysdocument­s.html
. Jul 10, 2003

6.1.2

Q: What was the first stretch of Interstate to open?

A: The first stretch of Interstate opened under the 1944 Congress act
was I-70 in Kansas, which opened in 1957. More information is at
http://www.tfhrc.go­v/pubrds/summer96/p9­6su18.htm 2000-08-17 15:29:33

6.1.3

Q: What were the original plans for Interstates?

A: The Interstate System's original plans are detailed in a publication
called General location of national system of interstate highways,
including all additional routes at urban areas designated in September,
1955, commonly known as the "Yellow Book". Go to
http://www.roadfan.­com/intreg.html#yell­owbk for much more information
including maps. Feb 25, 2002

6.2 Interstate Numbering

There's a very strict plan for numbering Interstate routes. The one and
two-digit routes are the mainlines, with the even numbered routes going
east-west, and the odd routes going north-south. The even routes'
numbers increase as you go north, with the odd Interstate roads
increasing to the east. The major routes end in 0 or 5. As for
three-digit interstates, those that both start and end at a 2-digit
route get an even first digit, while those not connected to the
Interstate system at their end or ends have an odd first digit.
Exceptions to this occur usually when a state has depleted its
respective choices for 3-digit Interstates. If a 3-digit Interstate has
another 3-digit Interstate branching from it (a "grandchild"), then the
numbering for the second-generation highway is the same as for the
first-generation one. In the field are I-105 CA, I-235 KS, I-444 OK,
I-370 MD, I-175/375 FL, I-278/478/678/878 NJ/NY, I-579 PA,
I-280/380/980 CA, I-190 MA, I-590/990 NY, I-495 NY, I-695 DC, and I-795
MD (each intersects with another 3di with a common "root" but not with
its 2di parent). I-195 NJ also used to be one but it now intersects
I-95 directly. For more on numbering see the FHWA site at
http://www.fhwa.dot­.gov/programadmin/in­terstate.html#Inters­tate_Numbering
. Apr 14, 2004

6.2.1 Letter Suffixes

6.2.1.1

Q: What happened to letter extensions on Interstate highways?

A: AASHTO eliminated them in 1980 and told state DOTs to think of other
numbers. Two still remain on I-35. I-15E in California stayed until
1983 (see 6.2.1.3). Jan 18, 2002

6.2.1.2

Q: Why does I-35 split in Dallas and Minneapolis?

A: As stated in the previous question, some Interstates once carried
letter suffixes. All but three were changed in 1980, and one of those
(I-15E in CA) was gone by 1983. The remaining two are the I-35 splits
in Dallas and Minneapolis, which remain because there was no consensus
on what the new numbers would be. The smaller cities, St. Paul and Fort
Worth, did not want their Interstate highways "demoted" to 3di's. Jul
9, 2003

6.2.1.3

Q: What are/were all the suffixed interstates?

A:

Actually existed

I-5W (CA) -- I-505, I-80, I-580, I-205 (see
http://www.cahighwa­ys.org/001-008.html#­005 for details)
I-15E (CA) -- I-215 (see http://www.cahighwa­ys.org/009-016.html#­015 ,
section 2, for details)
I-15W (ID) -- western I-86
I-24W (MO/TN) -- I-155 and US 412
I-35W/I-35E still exists in TX and MN (see 6.2.1.2)
I-35W (KS) -- I-135
I-59B (AL) -- I-459 (Note: "59B" was chosen through a system of
placeholder numbers using "A", "B", etc., as opposed to "B" meaning
"bypass")
I-70N/I-70S (MD) -- I-70/I-270
I-70S (PA) -- I-70 between I-79 and I-76
I-75E (FL) -- I-75 between I-275 termini
I-80N (OR/ID/UT) -- western I-84
I-80N (IA) -- I-680 east of I-29
I-80N (OH) -- I-80/90, I-90, I-490, I-480, and OH 14 between US 250
near Norwalk and I-76 near Ravenna
I-80S (CO/NE) -- western I-76
I-80S (OH/PA/NJ) at first used today's I-76 in OH and PA and I-276 in
PA; later it was rerouted on today's I-76 and I-676 through
Philadelphia and Camden rather than around; and later it was truncated
at today's I-376 when I-76 was created along today's I-376 and the PA
Turnpike
(See http://www.roadfan.­com/ohiomaps.html ,
http://www.pahighwa­ys.com/interstates/p­di.html#I80S , and
http://www.fhwa.dot­.gov/infrastructure/­i76.htm for details on the
OH/PA/NJ I-80N/I-80 and I-80/I-80S)
I-81E (PA) -- I-380
I-180N (ID) -- I-184 in Boise; all other spurs of suffixed 2dis were
non-suffixed


Planned but never signed

The sources for these are the 1957 and 1958 maps on
http://www.roadfan.­com/5758int.html -- see 6.1.3 for more details

I-5E (CA) -- I-5 between I-5W termini (see above)
I-80N (PA/NJ) -- I-78
I-80S (PA) -- I-76 east of Harrisburg
I-81S (PA) -- I-81E (see above)
I-82N (ID) -- I-15W (see above)
I-82S (ID/UT) -- I-80N between I-15W (see above) and I-15
I-90N (NY) -- I-190
I-94N (MI) -- I-196 (now I-96 west of Grand Rapids)
I-95E (RI/MA) -- I-195 (pre-Interstate plans called it US 6)

Dec 4, 2004

ber?

A: This has been one of the most contentious questions or topics in the
newsgroup. Unlike other interstate highways, which have their numbers
assigned by AASHTO, I-99's number was assigned in a piece of
appropriations legislation sponsored by former Rep. Bud Shuster
(R-Pa.), through whose district the highway ran.

Many of the regulars on m.t.r take issue with this highway designation
because:

1) Its number was written into law, as described above;

2) Its number is out of place--a highway designated as I-99 should run
right along the Atlantic coast; and

3) From its length (under 70 miles), location (in an area where all the
available 2di designations are already being used), route (basically, a
spur from I-76 to the Altoona/State College area, at least until it
connects to I-80), and the fact that it doesn't come close to any
interstate other than I-76, an odd 3di designation (such as I-576)
would be more appropriate.

As a side note, for now I-99 also has the distinction of being the only
2 digit interstate that does not have a direct interchange with any
other interstate.

More information is available at
http://www.pahighwa­ys.com/interstates/I­99.html . Oct 3, 2004

6.2.3

Q: What is I-238?

A: Interstate 238 is a 2-mile freeway on the east side of San Francisco
Bay, California. It is not numbered according to the regular Interstate
numbering conventions; rather, it was an extension of CA 238. There is
no I-38. More information is at http://www.gbcnet.c­om/roads/I-238/ .
May 28, 2002

6.2.4

Q: Why are there two Interstates 76, 84, 86 and 88?

A: All duplicates but 86 arose around the time when most letter
suffixes on Interstates were removed, though not all replaced a
suffixed Interstate designation. Eastern I-86 (see 6.3.6) was recently
added because there were no other choices that would fit. At one time,
an eastern I-86 existed from Hartford, CT to I-90 in MA; this is now
part of I-84 (see http://www.kurumi.c­om/roads/ct/i86.html­ ). There were
also two I-39s, but I-39 is now signed along I-90 between the two
sections (see http://www.intersta­te-guide.com/i-039.h­tml ). May 13,
2003

6.2.5

Q: Which 3di spurs go both directions from a parent?

A: I-305 CA (hidden), I-516 GA, I-540 AR (small overlap with I-40),
I-170 MO (crosses I-70, ends at I-270), I-580 CA (small overlap with
I-80), I-181 TN (to be replaced by I-26), I-390 NY (crosses I-90, ends
at I-490), I-394 MN (crosses I-94, ends at I-494), I-595 FL; future:
I-710 CA, I-355 IL, I-195 NJ Jan 29, 2004

6.3 Oddities

6.3.1

Q: What happens to I-95 in NJ?

A: The short explaination is the "NIMBY factor". Residents of the
Princeton and New Brunswick, NJ, areas managed to kill a section of
I-95 through their towns in the early 1980s; the NJ Turnpike also
opposed it as it would provide an alternate to the toll road. There has
been a gap ever since. On the NJ Turnpike, the I-95 signs disappear.
There is a plan to build an interchange connecting the existing I-95
with the PA Turnpike northeast of Philadelphia, where they currently
cross but do not have an interchange. The new routing would follow the
PA Turnpike connector from the NJ Turnpike across the Delaware River to
the new interchange, where it would resume its old route. This
interchange should be complete around 2008. More information is
available at http://www.njfreewa­ys.com/Interstate_95­_Gap.html ,
http://www.nycroads­.com/roads/I-95_NJ/ , and
http://www.paturnpi­ke.com/i95/ . This will complete the gap between New
York City and Philadelphia, but will not provide easy access to I-287
from Philadelphia for bypassing New York City as original I-95 would
have.
Some propose rerouting I-95 on the NJ Turnpike all the way to the
Delaware Memorial Bridge and I-295; this is how most through traffic
goes anyway. Many people have a problem with this because it would
bypass Philadelphia. Sep 30, 2004

6.3.1.1

Q: Are I-95's exit numbers between I-80 and NY an extension of I-80's?

A: No. Those numbers are based on the original mileage of I-95 in NJ
including the unbuilt portion mentioned above in 6.3.1 (see the
relevant section of http://www.nycroads­.com/roads/I-95_NJ/ ). Sep 30,
2004

6.3.2

Q: Why do some Interstates, such as I-180 in WY, have traffic lights or
at-grade intersections?

A: Usually Interstates are not allowed to have any cross traffic. In
fact at-grade intersections have kept the new I-86 in New York from
extending further east. But in these cases, AASHTO granted variances
because there was no other reasonable way to build them.
Wyoming I-180 is the only Interstate with no freeway portions. There
are three stoplights. Why was it commissioned in the first place? The
state of Wyoming wanted an Interstate serving downtown Cheyenne. It was
to be freeway, but that idea was rejected. More information is at
http://www.rockymou­ntainroads.com/wyomi­ng/i-180.html
I-676 in Philadelphia, PA has some traffic lights between the Vine St
Expressway and the Ben Franklin Bridge. Construction of a freeway
connection would impact several historic landmarks. There is some doubt
among roadgeeks as to whether I-676 actually goes this way; the
official PennDOT maps label the freeway connection to I-95 as 0676 and
put US 30 on the Ben Franklin Bridge. There is an I-676 shield on the
county map, but shields reflect actual signage, not internal
designations (as the 0676 does). NJDOT however takes I-676 over the
bridge officially and in signage. (See
http://www.pahighwa­ys.com/interstates/I­676.html)
I-78 in Jersey City, NJ runs along a one-way pair of surface streets
between the end of the Turnpike Extension and the Holland Tunnel. I-78
ends just across the border in Manhattan, New York City, so it could be
truncated, but hasn't been. NJ 139 also runs along those streets, as if
NJDOT were prepared for truncation. FHWA, NJDOT, and NYSDOT all
officially refer to these last few miles as I-78. (See also 12.2 )
I-70 in Breezewood, PA is the most famous of these. It runs along a
short section of US 30 lined with businesses between the north-south
free portion of I-70 and the Turnpike connection. It would be fairly
easy to construct direct ramps, but the businesses have been successful
in blocking them. Some think the influential congressman Bud Shuster
has helped block the ramps. (See 3.1 above)
I-585 in Spartanburg, SC is signed past the end of the freeway past
several traffic lights. It is unknown why; the road is also US 176.
(See 6.3.9)
I-690 at the NY State Fairgrounds in Syracuse has a pedestrian crossing
that only functions during the NY State Fair. Because this is only in
operation for a small period of time, it is not worth it to build an
overpass.
I-8, I-10 and I-17 in AZ, I-40 in NC, I-10 and I-40 in W. TX, and I-40
in NM have some at-grade intersections for forest, farm, and ranch
access (see http://www.arizonar­oads.com/wrong/). Most of these highways
were built directly over a pre-existing rural two-lane road, so this is
the only access for many of these properties. Interchanges would not be
worth the expense due to the extremely low traffic which these
intersecting roads carry (some in fact are private).
AK Interstates have signals, but that is because those Interstate
designations are "hidden" along state highways which are usually
surface roads with at-grade intersections (see Question 6.3.8 ).

Several other interstates end at traffic lights, but this is perfectly
OK as long as this is not a 3di's only connection to its parent or an
even 3di's only connection to another interstate at one end.
One example of this that is often brought up is I-587 is Kingston, NY;
this connects to the I-87 ramp via a traffic circle. However, a traffic
circle is somewhat up to standards; there is no cross traffic.
In fact there is a case of a 3DI not meeting its parent; the
abovementioned I-585 in Spartanburg, SC ends at Business Loop I-85,
which is the old I-85 (and is a freeway, but not up to full interstate
standards). It continues to I-85 (bypass) as 4 lane US 176, which is
due for upgrades soon. (See 6.3.9)
I-65 in NW IN formerly had a traffic light installed in 1980 at the IN
Toll Road (I-90) connection at the north end (map at
http://terraserver-­usa.com/image.aspx?t­=4&s=11&z=16&x=1186&­y=11510&w=3
); this was considered by INDOT to be mainline I-65 (
http://www.in.gov/d­ot/div/technology/in­terchanges/I65/is262­.pdf - note
that this diagram shows the rail crossing just north of the signalized
intersection as active; it actually was abandoned by the time I-65 was
extended northward to US-12/20) but was not really the same case of a
traffic light on an Interstate as other examples because the section
north of this signal functioned more like a ramp pair, and was probably
considered one by AASHTO. This has been replaced by conventional
grade-separated freeway ramps.
I-291 in Springfield, MA, has an access point at I-90/MA Turnpike
similar to the former I-65/I-90 junction cited above, albeit with a
more simple design (
http://terraserver-­usa.com/image.aspx?T­=4&S=10&Z=18&X=3514&­Y=23353&W=3
).

Several tunnels on the system have signals at their portals, either to
stop unwanted vehicles from entering (too tall, too heavy, too wide,
hazardous material carrier) or for traffic capacity control.

Question 6.3.7 deals with drawbridges on Interstates, which have
traffic lights but no cross traffic.

Railroad crossings:
The Interstate highway specifications do not permit railroad grade
crossings. A few did exist before, but all have either been grade
separated or had the tracks removed. However, a number of crossings do
still exist on some non-Interstate highways with controlled access. In
many of these cases, the crossing is classified as "Exempt" by the
particular state, meaning that vehicles normally required to stop at
railroad crossings, such as vehicles carrying hazardous material and
school buses, can continue through without stopping. Instead, all
trains are required to send a flagman to clear the highway traffic
before it may proceed. These crossings are rarely busy railroad
mainlines, as they tend to be lightly-used or even disused industrial
spurs. Exempt crossings are noted with a tab on the advance RxR warning
sign post and/or on the crossbuck post itself (see
http://mutcd.fhwa.d­ot.gov/HTM/2003r1/pa­rt8/part8b.htm#secti­on8B05 ).

Former crossings on Interstates:
I-65 north end in IN (see above). Abandoned, then interchange
reconstructed.
I-87 Adirondack Northway, NY, near the Mohawk River. This line was
apparently already up for abandonment with the now-defunct Interstate
Commerce Commission when the Interstate was being built, so it did not
pay to build an overpass that would be useless in a few years.
I-94 near Ypsilanti, MI. Now abandoned. This same line used to cross US
23 at-grade as well.
I-94 near Albion, MI. Now abandoned.
I-395 in N. VA (Shirley Highway) near Glebe Rd. Crossing dismantled
when the Washington & Old Dominion RR folded. Note that this was while
it had its pre-Interstate designation (VA 350).

Existing crossings on non-Interstate controlled-access highways [* -
Exempt]: US 1, Edison, NJ (Jersey Freeway); US 4 near Rutland, VT; US
12/14/18/151, Madison, WI; US 30/250, Wooster, OH*; US 60, Springfield,
MO; US 63, Columbia, MO; US 151, Beaver Dam, WI; US 151, Waupun, WI; US
301, Rocky Mount, NC; US 322 between Harrisburg and Hershey, PA*; ; OH
7, north of Martins Ferry; Atlantic City-Brigantine Connector, NJ*

Other former grade crossings on major divided highways: US 1, Danvers,
MA; US 3, Billerica, MA; US 4, Portsmouth, NH; US 6, Denver, CO; US
12/14/18/151, Madison, WI (2 others in addition to the current one); US
23 south of Dundee, MI (and others); US 64, Tulsa, OK (2); US 131,
Kalamazoo, MI; MA 2, Concord; NY 17 (Quickway)/future I-86 near
Middletown, NY

Note: The above question refers to Interstate intersections with roads
which carry general traffic and not roadways such as maintenance roads
(intersections between these and freeways are common throughout the
U.S.). Mar 7, 2005

6.3.3

Q: Where was the Embarcadero Freeway and why was it torn down?

A: The Embarcadero Freeway, I-480, would have connected the Bay Bridge
to the Golden Gate Bridge in San Francisco, carrying mostly local
traffic. The first section north from I-80 was built. Most San
Francisco residents hated it because it blocked the view of the
waterfront from the other side. After a 1989 earthquake almost made it
collapse, it was permanently closed and torn down. The same thing
happened to the northern half and most of the upper deck of the Central
Skyway (US 101). Across the Bay in Oakland, part of the Cypress Freeway
(I-880) actually collapsed, killing some motorists. This double decker
freeway was torn down and rebuilt on a new alignment; the old alignment
is now a wide boulevard with a park in the middle.
More information is at http://www.cahighwa­ys.org/371-480.html#­480 and
http://www.kurumi.c­om/roads/3di/i480.ht­ml#480ca . Apr 9, 2004

6.3.4

Q: Why are these I-73 and I-74 signs popping up in North Carolina?

A: Interstate 73 and the 74 extension are specified in the ISTEA
legislation. I-73 will go from Sault Ste. Marie, Michigan to Myrtle
Beach, South Carolina, while the 74 extension will head east from its
present Cincinnati, Ohio terminus to Portsmouth, Ohio and be mostly
multiplexed with 73 south of there. A North Carolina portion south of
Greensboro was already freeway, so they installed signs there. Some
states are reluctant to build the new highway, specifically Ohio. More
information is at http://www.aaroads.­com/high-priority/co­rr05.html
2000-08-11 19:10:26

6.3.5

Q: Why are there freeway loops in Phoenix?

A: The loop freeways are not Interstates because they are funded by a
1/2 cent sales tax paid by county residents, not by Federal money. If
these freeways had waited for inclusion in the Interstate system, they
may have been delayed for years, or never been built at all. More
information is at http://www.arizonar­oads.com/urban/ . Jan 15, 2002

6.3.6 What is the new I-86?

The eastern I-86, the newest 2di, runs from just outside Erie, PA, to
East Corning, NY, along state route 17, the Southern Tier Expressway.
The move was designed to spurt economic development in the Elmira and
Binghamton areas. This part was designated in late 1999; it is planned
to extend east to I-87 at Harriman once the at-grade intersections are
eliminated. More information is at
http://www.aaroads.­com/high-priority/co­rr36.html Apr 8, 2002

6.3.6.1

Q: Does it really dip into Pennsylvania?

A: Yes, it does. Exit 60 (US 220) is entirely in Pennsylvania, and the
dip is complete with "STATE BORDER" signs. However, New York maintains
it. Maps: http://www.empirest­ateroads.com/maps/wa­verly.jpg ,
http://terraserver-­usa.com/image.aspx?S­=12&T=2&X=466&Y=5813­&Z=18&W=2 By
the way, this is not part of I-86 yet. Sep 2, 2003

6.3.7

Q: Where are all the drawbridges on the Interstate system?

A: These all had to get variances from FHWA to be approved into the
interstate system.
I-5, OR/WA (Columbia R) -- see
http://www.bizave.c­om/cgi-bin/photoalbu­m.cgi?photoalbum=pdx­bridges&slidetag=Int­erstate
I-64, VA (Elizabeth R) -- see
http://www.roadstot­hefuture.com/I64_VA_­Desc.html or
http://www.aaroadtr­ips.com/hampton_road­s.html
I-95/495, VA/DC/MD (Potomac R); see
http://www.roadstot­hefuture.com/Woodrow­_Wilson_Bridge.html (this is
planned to be replaced by a higher drawbridge - information at
http://www.wilsonbr­idge.com/ ) See also 12.2
I-110, MS (Back Bay) -- see http://southeastroa­ds.com/i-110_ms.html­
I-264, VA (Elizabeth R) -- see
http://www.roadstot­hefuture.com/I264_VA­_Desc.html or
http://www.aaroadtr­ips.com/hampton_road­s.html
I-278, NY (Bronx R) -- see http://www.nycroads­.com/roads/bruckner/­
I-280, NJ (Passaic R) -- see http://www.nycroads­.com/roads/I-280_NJ/­
I-280, OH (Maumee R) -- see http://www.roadfan.­com/toledo.html#prop­
(this is being replaced by a fixed span - information at
http://www.lookupto­ledo.org/)
I-695, MD (Curtis Cr) -- see
http://www.roadstot­hefuture.com/Balt_Ou­ter_Harbor.html

Former drawbridges replaced by fixed spans:
I-75, MI (Saginaw R) -- see
http://www.michigan­highways.org/indepth­/zilwaukee.html
I-95, FL (St. Johns R) -- see
http://www.dot.stat­e.fl.us/structures/b­otm/fullerwarren/ful­lerwarren.htm
I-95, NY (Hutchinson R) -- see
http://www.nycroads­.com/roads/new-engla­nd/
I-395 (originally I-95), DC/VA (Potomac R) -- see
http://www.roadstot­hefuture.com/14th_St­reet_Bridge.html (bridge is
still a drawbridge but has been rendered inoperable)
Dec 4, 2004

6.3.8


Q: Why are there Interstate highways in Hawaii? Are there plans for
Interstates in Alaska or Puerto Rico? Are there any freeways in Alaska
or Puerto Rico?

A: The Hxx Interstates were approved by AASHTO when Hawaii became a
state in 1959 to allow Hawaii to have Interstates (see
http://www.fhwa.dot­.gov/infrastructure/­hawaii.htm and
http://www.hawaiihi­ghways.com/FAQs-page­4.htm#why-Interstate­s ). Even
though Alaska and Hawaii do not connect directly to other states, their
highways fall into the same system as those in the other 48 states, so
while "Interstate" can't be literal, the name is there for consistency.
Alaska and Puerto Rico officially have Axx and PRxx routes,
respectively, but these are unsigned and, in Alaska's case at least,
generally not up to Interstate standards. In 1959, when Alaska became a
state, they asked for funding for fully standard Interstates on the
current corridors plus others, including one to Nome. This was
rejected. In 1981, FHWA added current routes A1-A4 to the Interstate
system as 2 lane rural arterials. The only Alaska Interstate routes
that have been upgraded to freeway are AK 1 (A1) east of downtown
Anchorage to just short of the AK 3 (Interstate A4) junction in Palmer,
and a few miles of AK 1 (Interstate A3) south of downtown Anchorage.
Puerto Rico has many rural and urban freeways (autopistas); most of the
rural freeways are tolled. The AK/HI/PR Interstates do not have an "I-"
preceding them in their abbreviations.
Here is a list of the Ax routes:

A1 follows AK 2 from the Canadian border to Tok Junction and then AK 1
to Anchorage.
A2 follows AK 2 from Tok Junction (AK 1) to Fairbanks.
A3 follows AK 1 from Anchorage to Soldotna.
A4 follows AK 3 from Palmer (AK 1) to Fairbanks.

Aug 17, 2004

6.3.9

Q: What's up with I-585 in Spartanburg, SC?

A: When the I-85 bypass around Spartanburg was built, old I-85 became
BUSINESS I-85. I-585 originally ended at I-85 like it should, but since
new I-85 was built it has not touched I-85.
Another oddity on I-585 is the fact that it is signed for several
blocks past the freeway end in downtown Spartanburg.
In other words, I-585 doesn't extend far enough to I-85 and extends too
far on the other end. See http://www.kurumi.c­om/roads/3di/i585.ht­ml and
http://www.intersta­te-guide.com/i-585_s­c.html . May 28, 2003

6.3.10

Q: Why is the Chicago Skyway no longer I-90?

A: In late 1999, Chicago added a TO banner to all the I-90 reassurance
markers on the city-maintained Skyway. Apparently the city was looking
at old records and realized it was never technically approved as an
interstate (see
http://groups-beta.­google.com/group/mis­c.transport.road/msg­/2044938ffca6c8b4
, message ID n9jig-2008991217310­001@chi-pm4-1a-40.th­eramp.net ).
Another strange fact about the Skyway is that it was built as a 10 mile
toll bridge. Illinois law at the time prohibited non-bridge toll roads,
so Chicago had to get it approved as a toll bridge over the Calumet
River.
In early March 2004 a plan to privatize the Skyway was proposed; this
plan was put into action in mid-October 2004. ("For Sale: Chicago
Skyway", Chicago Sun-Times, March 2, 2004; "Overseas investors to lease
Skyway from city", Chicago Tribune, October 15, 2004)
The Skyway has a McDonald's restaurant in the median by the toll plaza.
Related: http://www.n9jig.co­m/tollways.html Oct 21, 2004

6.3.11

Q: Why does I-180 in IL exist?

A: I-180 serves the town of Hennepin, population 707 (2000 census). It
was built to serve LTV steel, a major defense contractor. In the future
it may be extended south to Peoria, but it currently has almost no
traffic. See http://www.kurumi.c­om/roads/3di/i180.ht­ml#180il ,
http://www.n9jig.co­m/gallery/expw.html , and
http://www.intersta­te-guide.com/i-180_i­l.html . May 28, 2003

6.3.12

Q: What happened to I-265 in Nashville?

A: In late 2000, I-65 was rerouted along the former I-265, which
existed between I-24 and I-40 northwest of downtown, to relieve traffic
on the former I-40/65 multiplex (now I-40 between I-65 and I-24). See
http://www.kurumi.c­om/roads/3di/ix65.ht­ml#265tn and
http://www.intersta­te-guide.com/i-265_t­n.html . May 28, 2003

6.3.13

Q: Are Kentucky's parkways built to Interstate standards?

A: No, according to Carl Dixon, Branch Manager, Division of Planning,
Kentucky Transportation Cabinet. Each of Kentucky's parkways would
require work to reach the standards defined for Interstates. Work that
would be required depends on the parkway; however, the work would
"include more lanes (e.g., the Daniel Boone Parkway), wider median
widths, wider shoulders, reduced grades, smoother curves, improved
interchanges, and possibly several other design details". The Parkways,
however, do allow trucks. The "Parkway" designation stems from the fact
that that's what Kentucky called its toll highways (not all of these
are tolled anymore). I-66 is planned to run along the Cumberland
Parkway and possibly the Boone, Natcher, and Western Kentucky Parkways,
and I-69 is planned to run along the Purchase Parkway and possibly the
Pennyrile and Western Kentucky Parkways (see
http://www.kentucky­roads.com/i-66/ and
http://www.kentucky­roads.com/i-69/ ). Jan 28, 2002

6.3.14

Q: Why do I-17's exit numbers start so high?

A: Until the mid-1980s Arizona used a special system for its mileage --
any route which did not enter Arizona from another state used the
mileage of the route where its southern or western end was for its
point of origin rather than zero (e.g.: If Route 2's southern end was
at Route 1 and Route 1's mileage at the Route 1/Route 2 intersection is
Mile 57, then Route 2's lowest-numbered milemarker would be Mile 57).
I-17 is a special case: Its exit numbers are actually those of the
former longer routing of AZ 69, which branched from US 89 at Mile 201,
since I-17 and AZ 69 were paired early on. AZ 69 has been truncated
since I-17's exits were numbered (see
http://www.arizonar­oads.com/arizona/az6­9.htm ). I-17's exit numbers are
not related to those of I-19 (see 10.3). Feb 20, 2002

6.3.15

Q: What's with the I-465 spur northwest of Indianapolis? What is it
designated?

A: I-865, the east-west I-465 spur which connects I-65 to I-465
northwest of Indianapolis, exists partly because the I-65/I-465
interchange farther south lacks ramps between the north and northwest
(it also has no ramps between the south and southeast). It was formerly
signed as I-465 East eastbound and I-65 North westbound (the I-65/I-465
spur interchange also lacks connections, between the southeast and
east) and was simply considered another part of I-465. It was
renumbered to I-865 in April 2002 and signage was changed beginning in
May 2002. Why it is now called I-865 is thoroughly explained in an
Indiana DOT press release (see
http://www.in.gov/s­erv/presscal?PF=dot&­Clist=6&Elist=52862 ). The spur
also carries US 52, which, while not signposted along most of I-465
(see 3.9.1), is in fact signed along the length of the spur. The
milemarkers on this spur used to start at 900 before it was renumbered.
See also http://www.kurumi.c­om/roads/3di/ix65.ht­ml#465in . Jun 11, 2002

6.3.16

Q: Has there been a proposal to extend eastern I-76 eastward?

A: Not officially. Many laypeople have proposed this extension, which
entails the freeway portion of NJ 42 plus most or all of the Atlantic
City Expressway, but this has not been considered officially due to a
combination of sub-Interstate features, potential confusion, and
disinterest (see
http://groups-beta.­google.com/group/mis­c.transport.road/bro­wse_frm/thread/4a67d­49058462018
). Oct 16, 2003

6.4

Q: Why do people want I-69 extended?

A: The I-69 extension was proposed by businessmen in the early 1990s to
stimulate international trade between Canada, Mexico and the United
States. It would run from Port Huron, Michigan to Brownsville, Texas.
It currently runs from Port Huron to Indianapolis. In Indiana, it was
decided that I-69 will run along a new alignment from Indianapolis to
Evansville (it will probably multiplex with I-465 around Indianapolis)
rather than along I-70, a new southeast bypass of Terre Haute, and an
upgraded US 41. More information is at
http://www.aaroads.­com/high-priority/co­rr18.html ,
http://www.i69info.­com/ , and
http://dmoz.org/Rec­reation/Roads_and_Hi­ghways/Interstate_69­/ . Jul 9,
2003

6.5

Q: What's this I hear about a new Interstate marker?

A: This is a hoax. Basically the rumor was that AASHTO plans to
implement a new shield design by 2007 or earlier. It was a circle in a
square, considered ugly by most.

6.6

Q: Is one mile of each five in the Interstate system required to be
able to act as an emergency landing strip for aircraft?

A: No. See http://www.tfhrc.go­v/pubrds/mayjun00/on­emileinfive.htm
(official) and http://www.snopes.c­om/autos/law/airstri­p.asp . It was
considered briefly ( http://www.fhwa.dot­.gov/infrastructure/­turner.htm
) but never adopted officially. There are unusually-built overpasses
(truss structure) on a straight section of I-75 near the former
Kincheloe Air Force Base (now Chippewa County International Airport) in
the Upper Peninsula of Michigan, leading to speculation that the
Michigan State Highway Department did build I-75 here to accomodate
aircraft. This is purely speculation, however, with no conclusive proof
so far.

Conversely, there was a Cold-War bunker built under I-5 in Seattle, at
the Ravenna Boulevard overpass, by the state of Washington in the early
1960s (see http://www.historyl­ink.org/output.CFM?f­ile_ID=3705 ). Nov 6,
2003

a system in which truck drivers may use a transponder to bypass weigh
stations. For more information go to http://www.prepass.­com/ . Jan 22,
2002

6.8

Q: What is the largest city without an Interstate?

A: It is the consensus of m.t.r that Fresno, CA (2000 pop. 427,652), is
the most populous city in the U.S. without an Interstate within its
boundaries. The closest it has to an Interstate is CA 99, old US 99
(see 7.4.2). (Mesa, AZ, is expected to pass Fresno in population by the
2010 Census - it only has the US 60 freeway and part of the Phoenix
loop system - see 6.3.5 ). The largest cities with only one Interstate
are Austin, TX (2000 pop. 656,562), with I-35, and Colorado Springs, CO
(2000 pop. 360,890), with I-25. El Paso, TX (2000 pop. 563,662) has
only one signposted interstate, I-10, but also has "hidden" I-110 (see
http://www.kurumi.c­om/roads/3di/i110.ht­ml#110tx ). Oct 21, 2004

6.9 Interstate Standards

Interstates have higher standards than basic freeways. While freeways
require grade separation and interchanges in place of at-grade
intersections, Interstates also require, at minimum, 12' wide lanes, 6'
wide shoulders (4' paved - if there are three or more lanes, the left
shoulder should be 12', 10' of it paved), 36' medians in rural areas
and 10' medians in urban or mountainous areas, a design speed of 60 mph
in urban areas and 70 mph in rural areas (with speeds as low as 50 mph
in rugged terrain), acceleration and deceleration lane length to the
current standards of AASHTO (see 4.2), a maximum 6% grade and adequate
right-of-way. (1' equals about 0.30 meter, 1 mile equals about 1.61
kilometers) Exceptions can be granted (such as for the 8% grade on
I-24/US 64 Westbound over Monteagle Mountain, TN, the steepest on the
system - see also Question 12.6), but usually only are for pre-existing
older highways. For more information, see AASHTO's publication DS-4, A
Policy on Design Standards - Interstate System, available here on their
website. See 3.13 for tolls on Interstates.
Many non-Interstates are also built to Interstate standards. Respective
states can request that AASHTO include them in the system if the need
to do so exists (examples: http://www.kurumi.c­om/roads/3di/1970req­.html
). Feb 1, 2005

6.10

Q: Where is the longest stretch between services on an Interstate?

A: Eastern Utah, on I-70 between Green River and Salina (104 miles) --
see http://members.aol.­com/utahhwys/rte070.­htm . Jun 13, 2002

6.10.1

Q: Where is the longest stretch between other Interstates on an
Interstate?

A:
Between Interstates of any type: I-80 in NV/UT, unsigned I-580 to I-215
(511 miles)
Between signposted Interstates: I-80 in CA/NV/UT, I-5 to I-215 (647
miles)
Between 2di's: I-80 in CA/NV/UT, I-5 to I-15 (650 miles)
Mar 24, 2004

6.11 Tunnels

A compilation of Interstate (and other) tunnels and their locations is
at
http://groups-beta.­google.com/group/mis­c.transport.road/bro­wse_frm/thread/7922c­bdaff588381
Feb 1, 2005

6.12 Intrastate Interstates

As mentioned in the intro to this section, individual Interstates may
be found in only one state. Most 3di's are single-state; the single
state 2di's are I-4 (FL), I-12 (LA), I-16 (GA), I-17 (AZ), I-19 (AZ),
I-27 (TX), I-37 (TX), I-43 (WI), I-45 (TX), I-49 (LA), I-73 (NC - see
6.3.4), Western I-86 (ID), I-87 (NY), Both I-88's (IL, NY), I-96 (MI),
I-97 (MD), and I-99 (PA), plus the AK/HI/PR Interstates (see 6.3.8).
The only state which has I-66 is VA, but I-66 also enters DC (see
12.2). Dec 30, 2002

6.13 Multistate 3di's

Multistate three-digit Interstates are 205 (OR/WA), 129 (IA/NE), 435
(KS/MO), 535 (MN/WI), 635 (KS/MO), 155 (MO/TN), 2
Add comment
Marc Fannin 6 May 2005 02:35:41 [ permanent link ]
 Here are Sections 5 and 6.

The FAQ in its entirety is at http://www.roadfan.­com/mtrfaq.ÂÂÂhtml
(c. 250KB)

___________________­____________________­____________________­_____________
Marc Fannin|musxf579@ken­t.edu or @hotmail.com| http://www.roadfan.­com/

-------------------­--

5 Websites

Links to road websites are available at
http://dmoz.org/Rec­reation/Roads_and_Hi­ghways/ (alternate URL:
http://roadlinks.cj­b.net/ ),
http://www.aboutvia­.com/ (alternate URL:
http://www.ugcs.cal­tech.edu/~jlin/links­/ ),
http://www.aaroads.­com/kick-off/highway­.html , and
http://www.cahighwa­ys.org/othlinks.html­ .
(All of these are listed at
http://dmoz.org/Rec­reation/Roads_and_Hi­ghways/Directories/ .)

See also the Wikipedia "Road" entry and related subarticles at
http://en.wikipedia­.org/wiki/Roads .

A list of roadgeeks by location is at
http://www.roadfan.­com/roadfan.html .

Apr 3, 2005


-------------------­--------------------­--------------------­--------------------­-

6 The Interstate Highway System

The Interstate Highway System (or, more formally, the Dwight D.
Eisenhower National System of Interstate and Defense Highways) is a
system of divided controlled access highways present in every state as
well as DC and PR. It has more than 45,000 miles to its credit. A
complete list is found at http://www.ihoz.com­/interstates.html (1 and 2
digit) and http://www.kurumi.c­om/roads/3di/ (3 digit), as well as at
http://www.intersta­te-guide.com/ . Information on planned Interstates
and Interstate extensions can be found at
http://www.aaroads.­com/high-priority/ and
http://www.intersta­te-guide.com/future.­html . FHWA's overview of the
system is at http://www.fhwa.dot­.gov/programadmin/in­terstate.html , a
route log is at http://www.fhwa.dot­.gov/reports/routefi­nder/ , and some
history is located throughout
http://www.fhwa.dot­.gov/infrastructure/­history.htm . The U.S. Code of
Federal Regulations lists in Title 23, Appendix A to Subpart A of Part
470, the "Guidance Criteria for Evaluating Requests for Interstate
System Designations Under [Title] 23 [of the] U.S. [Code, now-repealed
Section] 139 (a) and (b)" (for text, see the portion directly after
Section 470.115 in the respective file at
http://www.access.g­po.gov/nara/cfr/wais­idx_04/23cfr470_04.h­tml ).
AASHTO's Interstate policy is at
http://www.richardc­moeur.com/inpolicy.h­tml . This policy states among
other items that Interstates and U.S. Highways with the same number
should not exist in the same state, although US 24 and I-24 both exist
in IL, and US 80 and I-80 briefly existed in CA until the former was
truncated outside the state (both instances presumedly overlooked due
to the distance between), and three proposed Interstate extensions are
planned to exist in states with the corresponding U.S. route (49 in AR,
69 in TX, 74 in NC - on current signage for the latter's pairing with
US 74, "FUTURE" replaces "INTERSTATE" on the I-74 shields). Also, there
are single-state Interstates (see 6.12) - the name "Interstate" refers
to the system as a whole and not to any individual numbered route. A
ranking subject to interpretation of 2-digit Interstates by importance
is located at http://www.kurumi.c­om/roads/rank2di.htm­l . For business
route information see 3.2. Apr 30, 2005

6.1 Interstate History

See also Section 17.

6.1.1

Q: How did the Interstate Highway System come to be?

A: In 1944, Congress authorized construction of an interstate
expressway system connecting major cities and industrial centers. No
money was involved in the bill. The project never took off until the
awarding of the first contract for I-70 in Missouri, in 1956. North
Dakota was the first state to complete its Interstates. More
information is available at
http://www.tfhrc.go­v/pubrds/summer96/p9­6su10.htm and
http://eisenhower.a­rchives.gov/dl/Inter­stateHighways/Inters­tateHighwaysdocument­s.html
. Jul 10, 2003

6.1.2

Q: What was the first stretch of Interstate to open?

A: The first stretch of Interstate opened under the 1944 Congress act
was I-70 in Kansas, which opened in 1957. More information is at
http://www.tfhrc.go­v/pubrds/summer96/p9­6su18.htm 2000-08-17 15:29:33

6.1.3

Q: What were the original plans for Interstates?

A: The Interstate System's original plans are detailed in a publication
called General location of national system of interstate highways,
including all additional routes at urban areas designated in September,
1955, commonly known as the "Yellow Book". Go to
http://www.roadfan.­com/intreg.html#yell­owbk for much more information
including maps. Feb 25, 2002

6.2 Interstate Numbering

There's a very strict plan for numbering Interstate routes. The one and
two-digit routes are the mainlines, with the even numbered routes going
east-west, and the odd routes going north-south. The even routes'
numbers increase as you go north, with the odd Interstate roads
increasing to the east. The major routes end in 0 or 5. As for
three-digit interstates, those that both start and end at a 2-digit
route get an even first digit, while those not connected to the
Interstate system at their end or ends have an odd first digit.
Exceptions to this occur usually when a state has depleted its
respective choices for 3-digit Interstates. If a 3-digit Interstate has
another 3-digit Interstate branching from it (a "grandchild"), then the
numbering for the second-generation highway is the same as for the
first-generation one. In the field are I-105 CA, I-235 KS, I-444 OK,
I-370 MD, I-175/375 FL, I-278/478/678/878 NJ/NY, I-579 PA,
I-280/380/980 CA, I-190 MA, I-590/990 NY, I-495 NY, I-695 DC, and I-795
MD (each intersects with another 3di with a common "root" but not with
its 2di parent). I-195 NJ also used to be one but it now intersects
I-95 directly. For more on numbering see the FHWA site at
http://www.fhwa.dot­.gov/programadmin/in­terstate.html#Inters­tate_Numbering
. Apr 14, 2004

6.2.1 Letter Suffixes

6.2.1.1

Q: What happened to letter extensions on Interstate highways?

A: AASHTO eliminated them in 1980 and told state DOTs to think of other
numbers. Two still remain on I-35. I-15E in California stayed until
1983 (see 6.2.1.3). Jan 18, 2002

6.2.1.2

Q: Why does I-35 split in Dallas and Minneapolis?

A: As stated in the previous question, some Interstates once carried
letter suffixes. All but three were changed in 1980, and one of those
(I-15E in CA) was gone by 1983. The remaining two are the I-35 splits
in Dallas and Minneapolis, which remain because there was no consensus
on what the new numbers would be. The smaller cities, St. Paul and Fort
Worth, did not want their Interstate highways "demoted" to 3di's. Jul
9, 2003

6.2.1.3

Q: What are/were all the suffixed interstates?

A:

Actually existed

I-5W (CA) -- I-505, I-80, I-580, I-205 (see
http://www.cahighwa­ys.org/001-008.html#­005 for details)
I-15E (CA) -- I-215 (see http://www.cahighwa­ys.org/009-016.html#­015 ,
section 2, for details)
I-15W (ID) -- western I-86
I-24W (MO/TN) -- I-155 and US 412
I-35W/I-35E still exists in TX and MN (see 6.2.1.2)
I-35W (KS) -- I-135
I-59B (AL) -- I-459 (Note: "59B" was chosen through a system of
placeholder numbers using "A", "B", etc., as opposed to "B" meaning
"bypass")
I-70N/I-70S (MD) -- I-70/I-270
I-70S (PA) -- I-70 between I-79 and I-76
I-75E (FL) -- I-75 between I-275 termini
I-80N (OR/ID/UT) -- western I-84
I-80N (IA) -- I-680 east of I-29
I-80N (OH) -- I-80/90, I-90, I-490, I-480, and OH 14 between US 250
near Norwalk and I-76 near Ravenna
I-80S (CO/NE) -- western I-76
I-80S (OH/PA/NJ) at first used today's I-76 in OH and PA and I-276 in
PA; later it was rerouted on today's I-76 and I-676 through
Philadelphia and Camden rather than around; and later it was truncated
at today's I-376 when I-76 was created along today's I-376 and the PA
Turnpike
(See http://www.roadfan.­com/ohiomaps.html ,
http://www.pahighwa­ys.com/interstates/p­di.html#I80S , and
http://www.fhwa.dot­.gov/infrastructure/­i76.htm for details on the
OH/PA/NJ I-80N/I-80 and I-80/I-80S)
I-81E (PA) -- I-380
I-180N (ID) -- I-184 in Boise; all other spurs of suffixed 2dis were
non-suffixed


Planned but never signed

The sources for these are the 1957 and 1958 maps on
http://www.roadfan.­com/5758int.html -- see 6.1.3 for more details

I-5E (CA) -- I-5 between I-5W termini (see above)
I-80N (PA/NJ) -- I-78
I-80S (PA) -- I-76 east of Harrisburg
I-81S (PA) -- I-81E (see above)
I-82N (ID) -- I-15W (see above)
I-82S (ID/UT) -- I-80N between I-15W (see above) and I-15
I-90N (NY) -- I-190
I-94N (MI) -- I-196 (now I-96 west of Grand Rapids)
I-95E (RI/MA) -- I-195 (pre-Interstate plans called it US 6)

Dec 4, 2004

6.2.2

Q: Why the heck does I-99 have such a weird number?

A: This has been one of the most contentious questions or topics in the
newsgroup. Unlike other interstate highways, which have their numbers
assigned by AASHTO, I-99's number was assigned in a piece of
appropriations legislation sponsored by former Rep. Bud Shuster
(R-Pa.), through whose district the highway ran.

Many of the regulars on m.t.r take issue with this highway designation
because:

1) Its number was written into law, as described above;

2) Its number is out of place--a highway designated as I-99 should run
right along the Atlantic coast; and

3) From its length (under 70 miles), location (in an area where all the
available 2di designations are already being used), route (basically, a
spur from I-76 to the Altoona/State College area, at least until it
connects to I-80), and the fact that it doesn't come close to any
interstate other than I-76, an odd 3di designation (such as I-576)
would be more appropriate.

As a side note, for now I-99 also has the distinction of being the only
2 digit interstate that does not have a direct interchange with any
other interstate.

More information is available at
http://www.pahighwa­ys.com/interstates/I­99.html . Oct 3, 2004

6.2.3

Q: What is I-238?

A: Interstate 238 is a 2-mile freeway on the east side of San Francisco
Bay, California. It is not numbered according to the regular Interstate
numbering conventions; rather, it was an extension of CA 238. There is
no I-38. More information is at http://www.gbcnet.c­om/roads/I-238/ .
May 28, 2002

6.2.4

Q: Why are there two Interstates 76, 84, 86 and 88?

A: All duplicates but 86 arose around the time when most letter
suffixes on Interstates were removed, though not all replaced a
suffixed Interstate designation. Eastern I-86 (see 6.3.6) was recently
added because there were no other choices that would fit. At one time,
an eastern I-86 existed from Hartford, CT to I-90 in MA; this is now
part of I-84 (see http://www.kurumi.c­om/roads/ct/i86.html­ ). There were
also two I-39s, but I-39 is now signed along I-90 between the two
sections (see http://www.intersta­te-guide.com/i-039.h­tml ). May 13,
2003

6.2.5

Q: Which 3di spurs go both directions from a parent?

A: I-305 CA (hidden), I-516 GA, I-540 AR (small overlap with I-40),
I-170 MO (crosses I-70, ends at I-270), I-580 CA (small overlap with
I-80), I-181 TN (to be replaced by I-26), I-390 NY (crosses I-90, ends
at I-490), I-394 MN (crosses I-94, ends at I-494), I-595 FL; future:
I-710 CA, I-355 IL, I-195 NJ Jan 29, 2004

6.3 Oddities

6.3.1

Q: What happens to I-95 in NJ?

A: The short explaination is the "NIMBY factor". Residents of the
Princeton and New Brunswick, NJ, areas managed to kill a section of
I-95 through their towns in the early 1980s; the NJ Turnpike also
opposed it as it would provide an alternate to the toll road. There has
been a gap ever since. On the NJ Turnpike, the I-95 signs disappear.
There is a plan to build an interchange connecting the existing I-95
with the PA Turnpike northeast of Philadelphia, where they currently
cross but do not have an interchange. The new routing would follow the
PA Turnpike connector from the NJ Turnpike across the Delaware River to
the new interchange, where it would resume its old route. This
interchange should be complete around 2008. More information is
available at http://www.njfreewa­ys.com/Interstate_95­_Gap.html ,
http://www.nycroads­.com/roads/I-95_NJ/ , and
http://www.paturnpi­ke.com/i95/ . This will complete the gap between New
York City and Philadelphia, but will not provide easy access to I-287
from Philadelphia for bypassing New York City as original I-95 would
have.
Some propose rerouting I-95 on the NJ Turnpike all the way to the
Delaware Memorial Bridge and I-295; this is how most through traffic
goes anyway. Many people have a problem with this because it would
bypass Philadelphia. Sep 30, 2004

6.3.1.1

Q: Are I-95's exit numbers between I-80 and NY an extension of I-80's?

A: No. Those numbers are based on the original mileage of I-95 in NJ
including the unbuilt portion mentioned above in 6.3.1 (see the
relevant section of http://www.nycroads­.com/roads/I-95_NJ/ ). Sep 30,
2004

6.3.2

Q: Why do some Interstates, such as I-180 in WY, have traffic lights or
at-grade intersections?

A: Usually Interstates are not allowed to have any cross traffic. In
fact at-grade intersections have kept the new I-86 in New York from
extending further east. But in these cases, AASHTO granted variances
because there was no other reasonable way to build them.
Wyoming I-180 is the only Interstate with no freeway portions. There
are three stoplights. Why was it commissioned in the first place? The
state of Wyoming wanted an Interstate serving downtown Cheyenne. It was
to be freeway, but that idea was rejected. More information is at
http://www.rockymou­ntainroads.com/wyomi­ng/i-180.html
I-676 in Philadelphia, PA has some traffic lights between the Vine St
Expressway and the Ben Franklin Bridge. Construction of a freeway
connection would impact several historic landmarks. There is some doubt
among roadgeeks as to whether I-676 actually goes this way; the
official PennDOT maps label the freeway connection to I-95 as 0676 and
put US 30 on the Ben Franklin Bridge. There is an I-676 shield on the
county map, but shields reflect actual signage, not internal
designations (as the 0676 does). NJDOT however takes I-676 over the
bridge officially and in signage. (See
http://www.pahighwa­ys.com/interstates/I­676.html)
I-78 in Jersey City, NJ runs along a one-way pair of surface streets
between the end of the Turnpike Extension and the Holland Tunnel. I-78
ends just across the border in Manhattan, New York City, so it could be
truncated, but hasn't been. NJ 139 also runs along those streets, as if
NJDOT were prepared for truncation. FHWA, NJDOT, and NYSDOT all
officially refer to these last few miles as I-78. (See also 12.2 )
I-70 in Breezewood, PA is the most famous of these. It runs along a
short section of US 30 lined with businesses between the north-south
free portion of I-70 and the Turnpike connection. It would be fairly
easy to construct direct ramps, but the businesses have been successful
in blocking them. Some think the influential congressman Bud Shuster
has helped block the ramps. (See 3.1 above)
I-585 in Spartanburg, SC is signed past the end of the freeway past
several traffic lights. It is unknown why; the road is also US 176.
(See 6.3.9)
I-690 at the NY State Fairgrounds in Syracuse has a pedestrian crossing
that only functions during the NY State Fair. Because this is only in
operation for a small period of time, it is not worth it to build an
overpass.
I-8, I-10 and I-17 in AZ, I-40 in NC, I-10 and I-40 in W. TX, and I-40
in NM have some at-grade intersections for forest, farm, and ranch
access (see http://www.arizonar­oads.com/wrong/). Most of these highways
were built directly over a pre-existing rural two-lane road, so this is
the only access for many of these properties. Interchanges would not be
worth the expense due to the extremely low traffic which these
intersecting roads carry (some in fact are private).
AK Interstates have signals, but that is because those Interstate
designations are "hidden" along state highways which are usually
surface roads with at-grade intersections (see Question 6.3.8 ).

Several other interstates end at traffic lights, but this is perfectly
OK as long as this is not a 3di's only connection to its parent or an
even 3di's only connection to another interstate at one end.
One example of this that is often brought up is I-587 is Kingston, NY;
this connects to the I-87 ramp via a traffic circle. However, a traffic
circle is somewhat up to standards; there is no cross traffic.
In fact there is a case of a 3DI not meeting its parent; the
abovementioned I-585 in Spartanburg, SC ends at Business Loop I-85,
which is the old I-85 (and is a freeway, but not up to full interstate
standards). It continues to I-85 (bypass) as 4 lane US 176, which is
due for upgrades soon. (See 6.3.9)
I-65 in NW IN formerly had a traffic light installed in 1980 at the IN
Toll Road (I-90) connection at the north end (map at
http://terraserver-­usa.com/image.aspx?t­=4&s=11&z=16&x=1186&­y=11510&w=3
); this was considered by INDOT to be mainline I-65 (
http://www.in.gov/d­ot/div/technology/in­terchanges/I65/is262­.pdf - note
that this diagram shows the rail crossing just north of the signalized
intersection as active; it actually was abandoned by the time I-65 was
extended northward to US-12/20) but was not really the same case of a
traffic light on an Interstate as other examples because the section
north of this signal functioned more like a ramp pair, and was probably
considered one by AASHTO. This has been replaced by conventional
grade-separated freeway ramps.
I-291 in Springfield, MA, has an access point at I-90/MA Turnpike
similar to the former I-65/I-90 junction cited above, albeit with a
more simple design (
http://terraserver-­usa.com/image.aspx?T­=4&S=10&Z=18&X=3514&­Y=23353&W=3
).

Several tunnels on the system have signals at their portals, either to
stop unwanted vehicles from entering (too tall, too heavy, too wide,
hazardous material carrier) or for traffic capacity control.

Question 6.3.7 deals with drawbridges on Interstates, which have
traffic lights but no cross traffic.

Railroad crossings:
The Interstate highway specifications do not permit railroad grade
crossings. A few did exist before, but all have either been grade
separated or had the tracks removed. However, a number of crossings do
still exist on some non-Interstate highways with controlled access. In
many of these cases, the crossing is classified as "Exempt" by the
particular state, meaning that vehicles normally required to stop at
railroad crossings, such as vehicles carrying hazardous material and
school buses, can continue through without stopping. Instead, all
trains are required to send a flagman to clear the highway traffic
before it may proceed. These crossings are rarely busy railroad
mainlines, as they tend to be lightly-used or even disused industrial
spurs. Exempt crossings are noted with a tab on the advance RxR warning
sign post and/or on the crossbuck post itself (see
http://mutcd.fhwa.d­ot.gov/HTM/2003r1/pa­rt8/part8b.htm#secti­on8B05 ).

Former crossings on Interstates:
I-65 north end in IN (see above). Abandoned, then interchange
reconstructed.
I-87 Adirondack Northway, NY, near the Mohawk River. This line was
apparently already up for abandonment with the now-defunct Interstate
Commerce Commission when the Interstate was being built, so it did not
pay to build an overpass that would be useless in a few years.
I-94 near Ypsilanti, MI. Now abandoned. This same line used to cross US
23 at-grade as well.
I-94 near Albion, MI. Now abandoned.
I-395 in N. VA (Shirley Highway) near Glebe Rd. Crossing dismantled
when the Washington & Old Dominion RR folded. Note that this was while
it had its pre-Interstate designation (VA 350).

Existing crossings on non-Interstate controlled-access highways [* -
Exempt]: US 1, Edison, NJ (Jersey Freeway); US 4 near Rutland, VT; US
12/14/18/151, Madison, WI; US 30/250, Wooster, OH*; US 60, Springfield,
MO; US 63, Columbia, MO; US 151, Beaver Dam, WI; US 151, Waupun, WI; US
301, Rocky Mount, NC; US 322 between Harrisburg and Hershey, PA*; ; OH
7, north of Martins Ferry; Atlantic City-Brigantine Connector, NJ*

Other former grade crossings on major divided highways: US 1, Danvers,
MA; US 3, Billerica, MA; US 4, Portsmouth, NH; US 6, Denver, CO; US
12/14/18/151, Madison, WI (2 others in addition to the current one); US
23 south of Dundee, MI (and others); US 64, Tulsa, OK (2); US 131,
Kalamazoo, MI; MA 2, Concord; NY 17 (Quickway)/future I-86 near
Middletown, NY

Note: The above question refers to Interstate intersections with roads
which carry general traffic and not roadways such as maintenance roads
(intersections between these and freeways are common throughout the
U.S.). Mar 7, 2005

6.3.3

Q: Where was the Embarcadero Freeway and why was it torn down?

A: The Embarcadero Freeway, I-480, would have connected the Bay Bridge
to the Golden Gate Bridge in San Francisco, carrying mostly local
traffic. The first section north from I-80 was built. Most San
Francisco residents hated it because it blocked the view of the
waterfront from the other side. After a 1989 earthquake almost made it
collapse, it was permanently closed and torn down. The same thing
happened to the northern half and most of the upper deck of the Central
Skyway (US 101). Across the Bay in Oakland, part of the Cypress Freeway
(I-880) actually collapsed, killing some motorists. This double decker
freeway was torn down and rebuilt on a new alignment; the old alignment
is now a wide boulevard with a park in the middle.
More information is at http://www.cahighwa­ys.org/371-480.html#­480 and
http://www.kurumi.c­om/roads/3di/i480.ht­ml#480ca . Apr 9, 2004

6.3.4

Q: Why are these I-73 and I-74 signs popping up in North Carolina?

A: Interstate 73 and the 74 extension are specified in the ISTEA
legislation. I-73 will go from Sault Ste. Marie, Michigan to Myrtle
Beach, South Carolina, while the 74 extension will head east from its
present Cincinnati, Ohio terminus to Portsmouth, Ohio and be mostly
multiplexed with 73 south of there. A North Carolina portion south of
Greensboro was already freeway, so they installed signs there. Some
states are reluctant to build the new highway, specifically Ohio. More
information is at http://www.aaroads.­com/high-priority/co­rr05.html
2000-08-11 19:10:26

6.3.5

Q: Why are there freeway loops in Phoenix?

A: The loop freeways are not Interstates because they are funded by a
1/2 cent sales tax paid by county residents, not by Federal money. If
these freeways had waited for inclusion in the Interstate system, they
may have been delayed for years, or never been built at all. More
information is at http://www.arizonar­oads.com/urban/ . Jan 15, 2002

6.3.6 What is the new I-86?

The eastern I-86, the newest 2di, runs from just outside Erie, PA, to
East Corning, NY, along state route 17, the Southern Tier Expressway.
The move was designed to spurt economic development in the Elmira and
Binghamton areas. This part was designated in late 1999; it is planned
to extend east to I-87 at Harriman once the at-grade intersections are
eliminated. More information is at
http://www.aaroads.­com/high-priority/co­rr36.html Apr 8, 2002

6.3.6.1

Q: Does it really dip into Pennsylvania?

A: Yes, it does. Exit 60 (US 220) is entirely in Pennsylvania, and the
dip is complete with "STATE BORDER" signs. However, New York maintains
it. Maps: http://www.empirest­ateroads.com/maps/wa­verly.jpg ,
http://terraserver-­usa.com/image.aspx?S­=12&T=2&X=466&Y=5813­&Z=18&W=2 By
the way, this is not part of I-86 yet. Sep 2, 2003

6.3.7

Q: Where are all the drawbridges on the Interstate system?

A: These all had to get variances from FHWA to be approved into the
interstate system.
I-5, OR/WA (Columbia R) -- see
http://www.bizave.c­om/cgi-bin/photoalbu­m.cgi?photoalbum=pdx­bridges&slidetag=Int­erstate
and http://www.columbia­n.com/reflections/br­idge.cfm (this is planned to
be replaced - information at http://www.columbia­rivercrossing.org/ )
I-64, VA (Elizabeth R) -- see
http://www.roadstot­hefuture.com/I64_VA_­Desc.html or
http://www.aaroadtr­ips.com/hampton_road­s.html
I-95/495, VA/DC/MD (Potomac R); see
http://www.roadstot­hefuture.com/Woodrow­_Wilson_Bridge.html (this is
being replaced by a higher drawbridge - information at
http://www.wilsonbr­idge.com/ ) See also 12.2
I-110, MS (Back Bay) -- see http://southeastroa­ds.com/i-110_ms.html­
I-264, VA (Elizabeth R) -- see
http://www.roadstot­hefuture.com/I264_VA­_Desc.html or
http://www.aaroadtr­ips.com/hampton_road­s.html
I-278, NY (Bronx R) -- see http://www.nycroads­.com/roads/bruckner/­
I-280, NJ (Passaic R) -- see http://www.nycroads­.com/roads/I-280_NJ/­
I-280, OH (Maumee R) -- see http://www.roadfan.­com/toledo.html#prop­
(this is being replaced by a fixed span - information at
http://www.lookupto­ledo.org/)
I-695, MD (Curtis Cr) -- see
http://www.roadstot­hefuture.com/Balt_Ou­ter_Harbor.html

Former drawbridges replaced by fixed spans:
I-75, MI (Saginaw R) -- see
http://www.michigan­highways.org/indepth­/zilwaukee.html
I-95, FL (St. Johns R) -- see
http://www.dot.stat­e.fl.us/structures/b­otm/fullerwarren/ful­lerwarren.htm
I-95, NY (Hutchinson R) -- see
http://www.nycroads­.com/roads/new-engla­nd/
I-395 (originally I-95), DC/VA (Potomac R) -- see
http://www.roadstot­hefuture.com/14th_St­reet_Bridge.html (bridge is
still a drawbridge but has been rendered inoperable)
Apr 30, 2005

6.3.8


Q: Why are there Interstate highways in Hawaii? Are there plans for
Interstates in Alaska or Puerto Rico? Are there any freeways in Alaska
or Puerto Rico?

A: The Hxx Interstates were approved by AASHTO when Hawaii became a
state in 1959 to allow Hawaii to have Interstates (see
http://www.fhwa.dot­.gov/infrastructure/­hawaii.htm and
http://www.hawaiihi­ghways.com/FAQs-page­4.htm#why-Interstate­s ). Even
though Alaska and Hawaii do not connect directly to other states, their
highways fall into the same system as those in the other 48 states, so
while "Interstate" can't be literal, the name is there for consistency.
Alaska and Puerto Rico officially have Axx and PRxx routes,
respectively, but these are unsigned and, in Alaska's case at least,
generally not up to Interstate standards. In 1959, when Alaska became a
state, they asked for funding for fully standard Interstates on the
current corridors plus others, including one to Nome. This was
rejected. In 1981, FHWA added current routes A1-A4 to the Interstate
system as 2 lane rural arterials. The only Alaska Interstate routes
that have been upgraded to freeway are AK 1 (A1) east of downtown
Anchorage to just short of the AK 3 (Interstate A4) junction in Palmer,
and a few miles of AK 1 (Interstate A3) south of downtown Anchorage.
Puerto Rico has many rural and urban freeways (autopistas); most of the
rural freeways are tolled. The AK/HI/PR Interstates do not have an "I-"
preceding them in their abbreviations.
Here is a list of the Ax routes:

A1 follows AK 2 from the Canadian border to Tok Junction and then AK 1
to Anchorage.
A2 follows AK 2 from Tok Junction (AK 1) to Fairbanks.
A3 follows AK 1 from Anchorage to Soldotna.
A4 follows AK 3 from Palmer (AK 1) to Fairbanks.

Aug 17, 2004

6.3.9

Q: What's up with I-585 in Spartanburg, SC?

A: When the I-85 bypass around Spartanburg was built, old I-85 became
BUSINESS I-85. I-585 originally ended at I-85 like it should, but since
new I-85 was built it has not touched I-85.
Another oddity on I-585 is the fact that it is signed for several
blocks past the freeway end in downtown Spartanburg.
In other words, I-585 doesn't extend far enough to I-85 and extends too
far on the other end. See http://www.kurumi.c­om/roads/3di/i585.ht­ml and
http://www.intersta­te-guide.com/i-585_s­c.html . May 28, 2003

6.3.10

Q: Why is the Chicago Skyway no longer I-90?

A: In late 1999, Chicago added a TO banner to all the I-90 reassurance
markers on the city-maintained Skyway. Apparently the city was looking
at old records and realized it was never technically approved as an
interstate (see
http://groups-beta.­google.com/group/mis­c.transport.road/msg­/2044938ffca6c8b4
, message ID n9jig-2008991217310­001@chi-pm4-1a-40.th­eramp.net ).
Another strange fact about the Skyway is that it was built as a 10 mile
toll bridge. Illinois law at the time prohibited non-bridge toll roads,
so Chicago had to get it approved as a toll bridge over the Calumet
River.
In early March 2004 a plan to privatize the Skyway was proposed; this
plan was put into action in mid-October 2004. ("For Sale: Chicago
Skyway", Chicago Sun-Times, March 2, 2004; "Overseas investors to lease
Skyway from city", Chicago Tribune, October 15, 2004)
The Skyway has a McDonald's restaurant in the median by the toll plaza.
Related: http://www.n9jig.co­m/tollways.html Oct 21, 2004

6.3.11

Q: Why does I-180 in IL exist?

A: I-180 serves the town of Hennepin, population 707 (2000 census). It
was built to serve LTV steel, a major defense contractor. In the future
it may be extended south to Peoria, but it currently has almost no
traffic. See http://www.kurumi.c­om/roads/3di/i180.ht­ml#180il ,
http://www.n9jig.co­m/gallery/expw.html , and
http://www.intersta­te-guide.com/i-180_i­l.html . May 28, 2003

6.3.12

Q: What happened to I-265 in Nashville?

A: In late 2000, I-65 was rerouted along the former I-265, which
existed between I-24 and I-40 northwest of downtown, to relieve traffic
on the former I-40/65 multiplex (now I-40 between I-65 and I-24). See
http://www.kurumi.c­om/roads/3di/ix65.ht­ml#265tn and
http://www.intersta­te-guide.com/i-265_t­n.html . May 28, 2003

6.3.13

Q: Are Kentucky's parkways built to Interstate standards?

A: No, according to Carl Dixon, Branch Manager, Division of Planning,
Kentucky Transportation Cabinet. Each of Kentucky's parkways would
require work to reach the standards defined for Interstates. Work that
would be required depends on the parkway; however, the work would
"include more lanes (e.g., the Daniel Boone Parkway), wider median
widths, wider shoulders, reduced grades, smoother curves, improved
interchanges, and possibly several other design details". The Parkways,
however, do allow trucks. The "Parkway" designation stems from the fact
that that's what Kentucky called its toll highways (not all of these
are tolled anymore). I-66 is planned to run along the Cumberland
Parkway and possibly the Boone, Natcher, and Western Kentucky Parkways,
and I-69 is planned to run along the Purchase Parkway and possibly the
Pennyrile and Western Kentucky Parkways (see
http://www.kentucky­roads.com/i-66/ and
http://www.kentucky­roads.com/i-69/ ). Jan 28, 2002

6.3.14

Q: Why do I-17's exit numbers start so high?

A: Until the mid-1980s Arizona used a special system for its mileage --
any route which did not enter Arizona from another state used the
mileage of the route where its southern or western end was for its
point of origin rather than zero (e.g.: If Route 2's southern end was
at Route 1 and Route 1's mileage at the Route 1/Route 2 intersection is
Mile 57, then Route 2's lowest-numbered milemarker would be Mile 57).
I-17 is a special case: Its exit numbers are actually those of the
former longer routing of AZ 69, which branched from US 89 at Mile 201,
since I-17 and AZ 69 were paired early on. AZ 69 has been truncated
since I-17's exits were numbered (see
http://www.arizonar­oads.com/arizona/az6­9.htm ). I-17's exit numbers are
not related to those of I-19 (see 10.3). Feb 20, 2002

6.3.15

Q: What's with the I-465 spur northwest of Indianapolis? What is it
designated?

A: I-865, the east-west I-465 spur which connects I-65 to I-465
northwest of Indianapolis, exists partly because the I-65/I-465
interchange farther south lacks ramps between the north and northwest
(it also has no ramps between the south and southeast). It was formerly
signed as I-465 East eastbound and I-65 North westbound (the I-65/I-465
spur interchange also lacks connections, between the southeast and
east) and was simply considered another part of I-465. It was
renumbered to I-865 in April 2002 and signage was changed beginning in
May 2002. Why it is now called I-865 is thoroughly explained in an
Indiana DOT press release (see
http://www.in.gov/s­erv/presscal?PF=dot&­Clist=6&Elist=52862 ). The spur
also carries US 52, which, while not signposted along most of I-465
(see 3.9.1), is in fact signed along the length of the spur. The
milemarkers on this spur used to start at 900 before it was renumbered.
See also http://www.kurumi.c­om/roads/3di/ix65.ht­ml#465in . Jun 11, 2002

6.3.16

Q: Has there been a proposal to extend eastern I-76 eastward?

A: Not officially. Many laypeople have proposed this extension, which
entails the freeway portion of NJ 42 plus most or all of the Atlantic
City Expressway, but this has not been considered officially due to a
combination of sub-Interstate features, potential confusion, and
disinterest (see
http://groups-beta.­google.com/group/mis­c.transport.road/bro­wse_frm/thread/4a67d­49058462018
). Oct 16, 2003

6.4

Q: Why do people want I-69 extended?

A: The I-69 extension was proposed by businessmen in the early 1990s to
stimulate international trade between Canada, Mexico and the United
States. It would run from Port Huron, Michigan to Brownsville, Texas.
It currently runs from Port Huron to Indianapolis. In Indiana, it was
decided that I-69 will run along a new alignment from Indianapolis to
Evansville (it will probably multiplex with I-465 around Indianapolis)
rather than along I-70, a new southeast bypass of Terre Haute, and an
upgraded US 41. More information is at
http://www.aaroads.­com/high-priority/co­rr18.html ,
http://www.i69info.­com/ , and
http://dmoz.org/Rec­reation/Roads_and_Hi­ghways/Interstate_69­/ . Jul 9,
2003

6.5

Q: What's this I hear about a new Interstate marker?

A: This is a hoax. Basically the rumor was that AASHTO plans to
implement a new shield design by 2007 or earlier. It was a circle in a
square, considered ugly by most.

6.6

Q: Is one mile of each five in the Interstate system required to be
able to act as an emergency landing strip for aircraft?

A: No. See http://www.tfhrc.go­v/pubrds/mayjun00/on­emileinfive.htm
(official) and http://www.snopes.c­om/autos/law/airstri­p.asp . It was
considered briefly ( http://www.fhwa.dot­.gov/infrastructure/­turner.htm
) but never adopted officially. There are unusually-built overpasses
(truss structure) on a straight section of I-75 near the former
Kincheloe Air Force Base (now Chippewa County International Airport) in
the Upper Peninsula of Michigan, leading to speculation that the
Michigan State Highway Department did build I-75 here to accomodate
aircraft. This is purely speculation, however, with no conclusive proof
so far.

Conversely, there was a Cold-War bunker built under I-5 in Seattle, at
the Ravenna Boulevard overpass, by the state of Washington in the early
1960s (see http://www.historyl­ink.org/output.CFM?f­ile_ID=3705 ). Nov 6,
2003

a system in which truck drivers may use a transponder to bypass weigh
stations. For more information go to http://www.prepass.­com/ . Jan 22,
2002

6.8

Q: What is the largest city without an Interstate?

A: It is the consensus of m.t.r that Fresno, CA (2000 pop. 427,652), is
the most populous city in the U.S. without an Interstate within its
boundaries. The closest it has to an Interstate is CA 99, old US 99
(see 7.4.2). (Mesa, AZ, is expected to pass Fresno in population by the
2010 Census - it only has the US 60 freeway and part of the Phoenix
loop system - see 6.3.5 ). The largest cities with only one Interstate
are Austin, TX (2000 pop. 656,562), with I-35, and Colorado Springs, CO
(2000 pop. 360,890), with I-25. El Paso, TX (2000 pop. 563,662) has
only one signposted interstate, I-10, but also has "hidden" I-110 (see
http://www.kurumi.c­om/roads/3di/i110.ht­ml#110tx ). Oct 21, 2004

6.9 Interstate Standards

Interstates have higher standards than basic freeways. While freeways
require grade separation and interchanges in place of at-grade
intersections, Interstates also require, at minimum, 12' wide lanes, 6'
wide shoulders (4' paved - if there are three or more lanes, the left
shoulder should be 12', 10' of it paved), 36' medians in rural areas
and 10' medians in urban or mountainous areas, a design speed of 60 mph
in urban areas and 70 mph in rural areas (with speeds as low as 50 mph
in rugged terrain), acceleration and deceleration lane length to the
current standards of AASHTO (see 4.2), a maximum 6% grade and adequate
right-of-way. (1' equals about 0.30 meter, 1 mile equals about 1.61
kilometers) Exceptions can be granted (such as for the 8% grade on
I-24/US 64 Westbound over Monteagle Mountain, TN, the steepest on the
system - see also Question 12.6), but usually only are for pre-existing
older highways. For more information, see AASHTO's publication DS-4, A
Policy on Design Standards - Interstate System, available here on their
website. See 3.13 for tolls on Interstates.
Many non-Interstates are also built to Interstate standards. Respective
states can request that AASHTO include them in the system if the need
to do so exists (examples: http://www.kurumi.c­om/roads/3di/1970req­.html
). Feb 1, 2005

6.10

Q: Where is the longest stretch between services on an Interstate?

A: Eastern Utah, on I-70 between Green River and Salina (104 miles) --
see http://members.aol.­com/utahhwys/rte070.­htm . Jun 13, 2002

6.10.1

Q: Where is the longest stretch between other Interstates on an
Interstate?

A:
Between Interstates of any type: I-80 in NV/UT, unsigned I-580 to I-215
(511 miles)
Between signposted Interstates: I-80 in CA/NV/UT, I-5 to I-215 (647
miles)
Between 2di's: I-80 in CA/NV/UT, I-5 to I-15 (650 miles)
Mar 24, 2004

6.11 Tunnels

A compilation of Interstate (and other) tunnels and their locations is
at
http://groups-beta.­google.com/group/mis­c.transport.road/bro­wse_frm/thread/7922c­bdaff588381
Feb 1, 2005

6.12 Intrastate Interstates

As mentioned in the intro to this section, indiv
Add comment
Marc Fannin 3 June 2005 04:52:00 [ permanent link ]
 Here are Sections 5 and 6.

The FAQ in its entirety is at
http://www.roadfan.­com/mtrfaq.ÂÂÂÂhtml
(c. 250KB)

___________________­____________________­____________________­_____________
Marc Fannin|musxf579@ken­t.edu or @hotmail.com| http://www.roadfan.­com/

-------------------­--

5 Websites

Links to road websites are available at
http://dmoz.org/Rec­reation/Roads_and_Hi­ghways/ (alternate URL:
http://roadlinks.cj­b.net/ ),
http://www.aboutvia­.com/ (alternate URL:
http://www.ugcs.cal­tech.edu/~jlin/links­/ ),
http://www.aaroads.­com/kick-off/highway­.html , and
http://www.cahighwa­ys.org/othlinks.html­ .
(All of these are listed at
http://dmoz.org/Rec­reation/Roads_and_Hi­ghways/Directories/ .)

See also the Wikipedia "Road" entry and related subarticles at
http://en.wikipedia­.org/wiki/Roads .

A list of roadgeeks by location is at
http://www.roadfan.­com/roadfan.html .

Apr 3, 2005


-------------------­--------------------­--------------------­--------------------­-

6 The Interstate Highway System

The Interstate Highway System (or, more formally, the Dwight D.
Eisenhower National System of Interstate and Defense Highways) is a
system of divided controlled access highways present in every state as
well as DC and PR. It has more than 45,000 miles to its credit. A
complete list is found at http://www.ihoz.com­/interstates.html (1 and 2
digit) and http://www.kurumi.c­om/roads/3di/ (3 digit), as well as at
http://www.intersta­te-guide.com/ . Information on planned Interstates
and Interstate extensions can be found at
http://www.aaroads.­com/high-priority/ and
http://www.intersta­te-guide.com/future.­html . FHWA's overview of the
system is at http://www.fhwa.dot­.gov/programadmin/in­terstate.html , a
route log is at http://www.fhwa.dot­.gov/reports/routefi­nder/ , and some
history is located throughout
http://www.fhwa.dot­.gov/infrastructure/­history.htm . The U.S. Code of
Federal Regulations lists in Title 23, Appendix A to Subpart A of Part
470, the "Guidance Criteria for Evaluating Requests for Interstate
System Designations Under [Title] 23 [of the] U.S. [Code, now-repealed
Section] 139 (a) and (b)" (for text, see the portion directly after
Section 470.115 in the respective file at
http://www.access.g­po.gov/nara/cfr/wais­idx_04/23cfr470_04.h­tml ).
AASHTO's Interstate policy is at
http://www.richardc­moeur.com/inpolicy.h­tml . This policy states among
other items that Interstates and U.S. Highways with the same number
should not exist in the same state, although US 24 and I-24 both exist
in IL, and US 80 and I-80 briefly existed in CA until the former was
truncated outside the state (both instances presumedly overlooked due
to the distance between), and three proposed Interstate extensions are
planned to exist in states with the corresponding U.S. route (49 in AR,
69 in TX, 74 in NC - on current signage for the latter's pairing with
US 74, "FUTURE" replaces "INTERSTATE" on the I-74 shields). Also, there
are single-state Interstates (see 6.12) - the name "Interstate" refers
to the system as a whole and not to any individual numbered route. A
ranking subject to interpretation of 2-digit Interstates by importance
is located at http://www.kurumi.c­om/roads/rank2di.htm­l . For business
route information see 3.2. Apr 30, 2005

6.1 Interstate History

See also Section 17.

6.1.1

Q: How did the Interstate Highway System come to be?

A: In 1944, Congress authorized construction of an interstate
expressway system connecting major cities and industrial centers. No
money was involved in the bill. The project never took off until the
awarding of the first contract for I-70 in Missouri, in 1956. North
Dakota was the first state to complete its Interstates. More
information is available at
http://www.tfhrc.go­v/pubrds/summer96/p9­6su10.htm and
http://eisenhower.a­rchives.gov/dl/Inter­stateHighways/Inters­tateHighwaysdocument­s.html
. Jul 10, 2003

6.1.2

Q: What was the first stretch of Interstate to open?

A: The first stretch of Interstate opened under the 1944 Congress act
was I-70 in Kansas, which opened in 1957. More information is at
http://www.tfhrc.go­v/pubrds/summer96/p9­6su18.htm 2000-08-17 15:29:33

6.1.3

Q: What were the original plans for Interstates?

A: The Interstate System's original plans are detailed in a publication
called General location of national system of interstate highways,
including all additional routes at urban areas designated in September,
1955, commonly known as the "Yellow Book". Go to
http://www.roadfan.­com/intreg.html#yell­owbk for much more information
including maps. Feb 25, 2002

6.2 Interstate Numbering

There's a very strict plan for numbering Interstate routes. The one and
two-digit routes are the mainlines, with the even numbered routes going
east-west, and the odd routes going north-south. The even routes'
numbers increase as you go north, with the odd Interstate roads
increasing to the east. The major routes end in 0 or 5. As for
three-digit interstates, those that both start and end at a 2-digit
route get an even first digit, while those not connected to the
Interstate system at their end or ends have an odd first digit.
Exceptions to this occur usually when a state has depleted its
respective choices for 3-digit Interstates. If a 3-digit Interstate has
another 3-digit Interstate branching from it (a "grandchild"), then the
numbering for the second-generation highway is the same as for the
first-generation one. In the field are I-105 CA, I-235 KS, I-444 OK,
I-370 MD, I-175/375 FL, I-278/478/678/878 NJ/NY, I-579 PA,
I-280/380/980 CA, I-190 MA, I-590/990 NY, I-495 NY, I-695 DC, and I-795
MD (each intersects with another 3di with a common "root" but not with
its 2di parent). I-195 NJ also used to be one but it now intersects
I-95 directly. For more on numbering see the FHWA site at
http://www.fhwa.dot­.gov/programadmin/in­terstate.html#Inters­tate_Numbering
. Apr 14, 2004

6.2.1 Letter Suffixes

6.2.1.1

Q: What happened to letter extensions on Interstate highways?

A: AASHTO eliminated them in 1980 and told state DOTs to think of other
numbers. Two still remain on I-35. I-15E in California stayed until
1983 (see 6.2.1.3). Jan 18, 2002

6.2.1.2

Q: Why does I-35 split in Dallas and Minneapolis?

A: As stated in the previous question, some Interstates once carried
letter suffixes. All but three were changed in 1980, and one of those
(I-15E in CA) was gone by 1983. The remaining two are the I-35 splits
in Dallas and Minneapolis, which remain because there was no consensus
on what the new numbers would be. The smaller cities, St. Paul and Fort
Worth, did not want their Interstate highways "demoted" to 3di's. Jul
9, 2003

6.2.1.3

Q: What are/were all the suffixed interstates?

A:

Actually existed

I-5W (CA) -- I-505, I-80, I-580, I-205 (see
http://www.cahighwa­ys.org/001-008.html#­005 for details)
I-15E (CA) -- I-215 (see http://www.cahighwa­ys.org/009-016.html#­015 ,
section 2, for details)
I-15W (ID) -- western I-86
I-24W (MO/TN) -- I-155 and US 412
I-35W/I-35E still exists in TX and MN (see 6.2.1.2)
I-35W (KS) -- I-135
I-59B (AL) -- I-459 (Note: "59B" was chosen through a system of
placeholder numbers using "A", "B", etc., as opposed to "B" meaning
"bypass")
I-70N/I-70S (MD) -- I-70/I-270
I-70S (PA) -- I-70 between I-79 and I-76
I-75E (FL) -- I-75 between I-275 termini
I-80N (OR/ID/UT) -- western I-84
I-80N (IA) -- I-680 east of I-29
I-80N (OH) -- I-80/90, I-90, I-490, I-480, and OH 14 between US 250
near Norwalk and I-76 near Ravenna
I-80S (CO/NE) -- western I-76
I-80S (OH/PA/NJ) at first used today's I-76 in OH and PA and I-276 in
PA; later it was rerouted on today's I-76 and I-676 through
Philadelphia and Camden rather than around; and later it was truncated
at today's I-376 when I-76 was created along today's I-376 and the PA
Turnpike
(See http://www.roadfan.­com/ohiomaps.html ,
http://www.pahighwa­ys.com/interstates/p­di.html#I80S , and
http://www.fhwa.dot­.gov/infrastructure/­i76.htm for details on the
OH/PA/NJ I-80N/I-80 and I-80/I-80S)
I-81E (PA) -- I-380
I-180N (ID) -- I-184 in Boise; all other spurs of suffixed 2dis were
non-suffixed


Planned but never signed

The sources for these are the 1957 and 1958 maps on
http://www.roadfan.­com/5758int.html -- see 6.1.3 for more details

I-5E (CA) -- I-5 between I-5W termini (see above)
I-80N (PA/NJ) -- I-78
I-80S (PA) -- I-76 east of Harrisburg
I-81S (PA) -- I-81E (see above)
I-82N (ID) -- I-15W (see above)
I-82S (ID/UT) -- I-80N between I-15W (see above) and I-15
I-90N (NY) -- I-190
I-94N (MI) -- I-196 (now I-96 west of Grand Rapids)
I-95E (RI/MA) -- I-195 (pre-Interstate plans called it US 6)

Dec 4, 2004

6.2.2

Q: Why the heck does I-99 have such a weird number?

A: This has been one of the most contentious questions or topics in the
newsgroup. Unlike other interstate highways, which have their numbers
assigned by AASHTO, I-99's number was assigned in a piece of
appropriations legislation sponsored by former Rep. Bud Shuster
(R-Pa.), through whose district the highway ran.

Many of the regulars on m.t.r take issue with this highway designation
because:

1) Its number was written into law, as described above;

2) Its number is out of place--a highway designated as I-99 should run
right along the Atlantic coast; and

3) From its length (under 70 miles), location (in an area where all the
available 2di designations are already being used), route (basically, a
spur from I-76 to the Altoona/State College area, at least until it
connects to I-80), and the fact that it doesn't come close to any
interstate other than I-76, an odd 3di designation (such as I-576)
would be more appropriate.

As a side note, for now I-99 also has the distinction of being the only
2 digit interstate that does not have a direct interchange with any
other interstate.

More information is available at
http://www.pahighwa­ys.com/interstates/I­99.html . Oct 3, 2004

6.2.3

Q: What is I-238?

A: Interstate 238 is a 2-mile freeway on the east side of San Francisco
Bay, California. It is not numbered according to the regular Interstate
numbering conventions; rather, it was an extension of CA 238. There is
no I-38. More information is at http://www.gbcnet.c­om/roads/I-238/ .
May 28, 2002

6.2.4

Q: Why are there two Interstates 76, 84, 86 and 88?

A: All duplicates but 86 arose around the time when most letter
suffixes on Interstates were removed, though not all replaced a
suffixed Interstate designation. Eastern I-86 (see 6.3.6) was recently
added because there were no other choices that would fit. At one time,
an eastern I-86 existed from Hartford, CT to I-90 in MA; this is now
part of I-84 (see http://www.kurumi.c­om/roads/ct/i86.html­ ). There were
also two I-39s, but I-39 is now signed along I-90 between the two
sections (see http://www.intersta­te-guide.com/i-039.h­tml ). There are
technically two I-74s, but these are planned to be connected, unlike
the other duplicates (see Question 6.3.4 ). May 6, 2005

6.2.5

Q: Which 3di spurs go both directions from a parent?

A: I-305 CA (hidden), I-516 GA, I-540 AR (small overlap with I-40),
I-170 MO (crosses I-70, ends at I-270), I-580 CA (small overlap with
I-80), I-181 TN (to be replaced by I-26), I-390 NY (crosses I-90, ends
at I-490), I-394 MN (crosses I-94, ends at I-494), I-595 FL; future:
I-710 CA, I-355 IL, I-195 NJ Jan 29, 2004

6.3 Oddities

6.3.1

Q: What happens to I-95 in NJ?

A: The short explaination is the "NIMBY factor". Residents of the
Princeton and New Brunswick, NJ, areas managed to kill a section of
I-95 through their towns in the early 1980s; the NJ Turnpike also
opposed it as it would provide an alternate to the toll road. There has
been a gap ever since. On the NJ Turnpike, the I-95 signs disappear.
There is a plan to build an interchange connecting the existing I-95
with the PA Turnpike northeast of Philadelphia, where they currently
cross but do not have an interchange. The new routing would follow the
PA Turnpike connector from the NJ Turnpike across the Delaware River to
the new interchange, where it would resume its old route. This
interchange should be complete around 2008. More information is
available at http://www.njfreewa­ys.com/Interstate_95­_Gap.html ,
http://www.nycroads­.com/roads/I-95_NJ/ , and
http://www.paturnpi­ke.com/i95/ . This will complete the gap between New
York City and Philadelphia, but will not provide easy access to I-287
from Philadelphia for bypassing New York City as original I-95 would
have.
Some propose rerouting I-95 on the NJ Turnpike all the way to the
Delaware Memorial Bridge and I-295; this is how most through traffic
goes anyway. Many people have a problem with this because it would
bypass Philadelphia. Sep 30, 2004

6.3.1.1

Q: Are I-95's exit numbers between I-80 and NY an extension of I-80's?

A: No. Those numbers are based on the original mileage of I-95 in NJ
including the unbuilt portion mentioned above in 6.3.1 (see the
relevant section of http://www.nycroads­.com/roads/I-95_NJ/ ). Sep 30,
2004

6.3.2

Q: Why do some Interstates, such as I-180 in WY, have traffic lights or
at-grade intersections?

A: Usually Interstates are not allowed to have any cross traffic. In
fact at-grade intersections have kept the new I-86 in New York from
extending further east. But in these cases, AASHTO granted variances
because there was no other reasonable way to build them.
Wyoming I-180 is the only Interstate with no freeway portions. There
are three stoplights. Why was it commissioned in the first place? The
state of Wyoming wanted an Interstate serving downtown Cheyenne. It was
to be freeway, but that idea was rejected. More information is at
http://www.rockymou­ntainroads.com/wyomi­ng/i-180.html
I-676 in Philadelphia, PA has some traffic lights between the Vine St
Expressway and the Ben Franklin Bridge. Construction of a freeway
connection would impact several historic landmarks. There is some doubt
among roadgeeks as to whether I-676 actually goes this way; the
official PennDOT maps label the freeway connection to I-95 as 0676 and
put US 30 on the Ben Franklin Bridge. There is an I-676 shield on the
county map, but shields reflect actual signage, not internal
designations (as the 0676 does). NJDOT however takes I-676 over the
bridge officially and in signage. (See
http://www.pahighwa­ys.com/interstates/I­676.html)
I-78 in Jersey City, NJ runs along a one-way pair of surface streets
between the end of the Turnpike Extension and the Holland Tunnel. I-78
ends just across the border in Manhattan, New York City, so it could be
truncated, but hasn't been. NJ 139 also runs along those streets, as if
NJDOT were prepared for truncation. FHWA, NJDOT, and NYSDOT all
officially refer to these last few miles as I-78. (See also 12.2 )
I-70 in Breezewood, PA is the most famous of these. It runs along a
short section of US 30 lined with businesses between the north-south
free portion of I-70 and the Turnpike connection. It would be fairly
easy to construct direct ramps, but the businesses have been successful
in blocking them. Some think the influential congressman Bud Shuster
has helped block the ramps. (See 3.1 above)
I-585 in Spartanburg, SC is signed past the end of the freeway past
several traffic lights. It is unknown why; the road is also US 176.
(See 6.3.9)
I-690 at the NY State Fairgrounds in Syracuse has a pedestrian crossing
that only functions during the NY State Fair. Because this is only in
operation for a small period of time, it is not worth it to build an
overpass.
I-8, I-10 and I-17 in AZ, I-40 in NC, I-10 and I-40 in W. TX, and I-40
in NM have some at-grade intersections for forest, farm, and ranch
access (see http://www.arizonar­oads.com/wrong/). Most of these highways
were built directly over a pre-existing rural two-lane road, so this is
the only access for many of these properties. Interchanges would not be
worth the expense due to the extremely low traffic which these
intersecting roads carry (some in fact are private).
AK Interstates have signals, but that is because those Interstate
designations are "hidden" along state highways which are usually
surface roads with at-grade intersections (see Question 6.3.8 ).

Several other interstates end at traffic lights, but this is perfectly
OK as long as this is not a 3di's only connection to its parent or an
even 3di's only connection to another interstate at one end.
One example of this that is often brought up is I-587 is Kingston, NY;
this connects to the I-87 ramp via a traffic circle. However, a traffic
circle is somewhat up to standards; there is no cross traffic.
In fact there is a case of a 3DI not meeting its parent; the
abovementioned I-585 in Spartanburg, SC ends at Business Loop I-85,
which is the old I-85 (and is a freeway, but not up to full interstate
standards). It continues to I-85 (bypass) as 4 lane US 176, which is
due for upgrades soon. (See 6.3.9)
I-65 in NW IN formerly had a traffic light installed in 1980 at the IN
Toll Road (I-90) connection at the north end (map at
http://terraserver-­usa.com/image.aspx?t­=4&s=11&z=16&x=1186&­y=11510&w=3
); this was considered by INDOT to be mainline I-65 (
http://www.in.gov/d­ot/div/technology/in­terchanges/I65/is262­.pdf - note
that this diagram shows the rail crossing just north of the signalized
intersection as active; it actually was abandoned by the time I-65 was
extended northward to US-12/20) but was not really the same case of a
traffic light on an Interstate as other examples because the section
north of this signal functioned more like a ramp pair, and was probably
considered one by AASHTO. This has been replaced by conventional
grade-separated freeway ramps.
I-291 in Springfield, MA, has an access point at I-90/MA Turnpike
similar to the former I-65/I-90 junction cited above, albeit with a
more simple design (
http://terraserver-­usa.com/image.aspx?T­=4&S=10&Z=18&X=3514&­Y=23353&W=3
).

Several tunnels on the system have signals at their portals, either to
stop unwanted vehicles from entering (too tall, too heavy, too wide,
hazardous material carrier) or for traffic capacity control.

Question 6.3.7 deals with drawbridges on Interstates, which have
traffic lights but no cross traffic.

Railroad crossings:
The Interstate highway specifications do not permit railroad grade
crossings. A few did exist before, but all have either been grade
separated or had the tracks removed. However, a number of crossings do
still exist on some non-Interstate highways with controlled access. In
many of these cases, the crossing is classified as "Exempt" by the
particular state, meaning that vehicles normally required to stop at
railroad crossings, such as vehicles carrying hazardous material and
school buses, can continue through without stopping. Instead, all
trains are required to send a flagman to clear the highway traffic
before it may proceed. These crossings are rarely busy railroad
mainlines, as they tend to be lightly-used or even disused industrial
spurs. Exempt crossings are noted with a tab on the advance RxR warning
sign post and/or on the crossbuck post itself (see
http://mutcd.fhwa.d­ot.gov/HTM/2003r1/pa­rt8/part8b.htm#secti­on8B05 ).

Former crossings on Interstates:
I-65 north end in IN (see above). Abandoned, then interchange
reconstructed.
I-87 Adirondack Northway, NY, near the Mohawk River. This line was
apparently already up for abandonment with the now-defunct Interstate
Commerce Commission when the Interstate was being built, so it did not
pay to build an overpass that would be useless in a few years.
I-94 near Ypsilanti, MI. Now abandoned. This same line used to cross US
23 at-grade as well.
I-94 near Albion, MI. Now abandoned.
I-395 in N. VA (Shirley Highway) near Glebe Rd. Crossing dismantled
when the Washington & Old Dominion RR folded. Note that this was while
it had its pre-Interstate designation (VA 350).

Existing crossings on non-Interstate controlled-access highways [* -
Exempt]: US-1, Edison, NJ (Jersey Freeway); US-4 near Rutland, VT;
US-12/14/18/151, Madison, WI; US-30/250, Wooster, OH*; US-60,
Springfield, MO; US-63, Columbia, MO; US 151, Beaver Dam, WI; US-151,
Waupun, WI; US-301, Rocky Mount, NC; US-322 between Harrisburg and
Hershey, PA*; NY-49 near Rome*; OH-7, north of Martins Ferry; Atlantic
City-Brigantine Connector, NJ*

Other former grade crossings on major divided highways: US-1, Danvers,
MA; US-3, Billerica, MA; US-4, Portsmouth, NH; US-6, Denver, CO;
US-12/14/18/151, Madison, WI (2 others in addition to the current one);
US-23 south of Dundee, MI (and others); US-64, Tulsa, OK (2); US-131,
Kalamazoo, MI; MA-2, Concord; NY-17 (Quickway)/future I-86 near
Middletown, NY

Note: The above question refers to Interstate intersections with roads
which carry general traffic and not roadways such as maintenance roads
(intersections between these and freeways are common throughout the
U.S.). May 7, 2005

6.3.3

Q: Where was the Embarcadero Freeway and why was it torn down?

A: The Embarcadero Freeway, I-480, would have connected the Bay Bridge
to the Golden Gate Bridge in San Francisco, carrying mostly local
traffic. The first section north from I-80 was built. Most San
Francisco residents hated it because it blocked the view of the
waterfront from the other side. After a 1989 earthquake almost made it
collapse, it was permanently closed and torn down. The same thing
happened to the northern half and most of the upper deck of the Central
Skyway (US 101). Across the Bay in Oakland, part of the Cypress Freeway
(I-880) actually collapsed, killing some motorists. This double decker
freeway was torn down and rebuilt on a new alignment; the old alignment
is now a wide boulevard with a park in the middle.
More information is at http://www.cahighwa­ys.org/371-480.html#­480 and
http://www.kurumi.c­om/roads/3di/i480.ht­ml#480ca . Apr 9, 2004

6.3.4

Q: Why are these I-73 and I-74 signs popping up in North Carolina?

A: Interstate 73 and the 74 extension are specified in the ISTEA
legislation. I-73 will go from Sault Ste. Marie, Michigan to Myrtle
Beach, South Carolina, while the 74 extension will head east from its
present Cincinnati, Ohio terminus to Portsmouth, Ohio and be mostly
multiplexed with 73 south of there. A North Carolina portion south of
Greensboro was already freeway, so they installed signs there. Some
states are reluctant to build the new highway, specifically Ohio. More
information is at http://www.aaroads.­com/high-priority/co­rr05.html
2000-08-11 19:10:26

6.3.5

Q: Why are there freeway loops in Phoenix?

A: The loop freeways are not Interstates because they are funded by a
1/2 cent sales tax paid by county residents, not by Federal money. If
these freeways had waited for inclusion in the Interstate system, they
may have been delayed for years, or never been built at all. More
information is at http://www.arizonar­oads.com/urban/ . Jan 15, 2002

6.3.6 What is the new I-86?

The eastern I-86, the newest 2di, runs from just outside Erie, PA, to
East Corning, NY, along state route 17, the Southern Tier Expressway.
The move was designed to spurt economic development in the Elmira and
Binghamton areas. This part was designated in late 1999; it is planned
to extend east to I-87 at Harriman once the at-grade intersections are
eliminated. More information is at
http://www.aaroads.­com/high-priority/co­rr36.html Apr 8, 2002

6.3.6.1

Q: Does it really dip into Pennsylvania?

A: Yes, it does. Exit 60 (US 220) is entirely in Pennsylvania, and the
dip is complete with "STATE BORDER" signs. However, New York maintains
it. Maps: http://www.empirest­ateroads.com/maps/wa­verly.jpg ,
http://terraserver-­usa.com/image.aspx?S­=12&T=2&X=466&Y=5813­&Z=18&W=2 By
the way, this is not part of I-86 yet. Sep 2, 2003

6.3.7

Q: Where are all the drawbridges on the Interstate system?

A: These all had to get variances from FHWA to be approved into the
interstate system.
I-5, OR/WA (Columbia R) -- see
http://www.bizave.c­om/cgi-bin/photoalbu­m.cgi?photoalbum=pdx­bridges&slidetag=Int­erstate
and http://www.columbia­n.com/reflections/br­idge.cfm (this is planned to
be replaced - information at http://www.columbia­rivercrossing.org/ )
I-64, VA (Elizabeth R) -- see
http://www.roadstot­hefuture.com/I64_VA_­Desc.html or
http://www.aaroadtr­ips.com/hampton_road­s.html
I-95/495, VA/DC/MD (Potomac R); see
http://www.roadstot­hefuture.com/Woodrow­_Wilson_Bridge.html (this is
being replaced by a higher drawbridge - information at
http://www.wilsonbr­idge.com/ ) See also 12.2
I-110, MS (Back Bay) -- see http://southeastroa­ds.com/i-110_ms.html­
I-264, VA (Elizabeth R) -- see
http://www.roadstot­hefuture.com/I264_VA­_Desc.html or
http://www.aaroadtr­ips.com/hampton_road­s.html
I-278, NY (Bronx R) -- see http://www.nycroads­.com/roads/bruckner/­
I-280, NJ (Passaic R) -- see http://www.nycroads­.com/roads/I-280_NJ/­
I-280, OH (Maumee R) -- see http://www.roadfan.­com/toledo.html#prop­
(this is being replaced by a fixed span - information at
http://www.lookupto­ledo.org/)
I-695, MD (Curtis Cr) -- see
http://www.roadstot­hefuture.com/Balt_Ou­ter_Harbor.html

Former drawbridges replaced by fixed spans:
I-75, MI (Saginaw R) -- see
http://www.michigan­highways.org/indepth­/zilwaukee.html
I-95, FL (St. Johns R) -- see
http://www.dot.stat­e.fl.us/structures/b­otm/fullerwarren/ful­lerwarren.htm
I-95, NY (Hutchinson R) -- see
http://www.nycroads­.com/roads/new-engla­nd/
I-395 (originally I-95), DC/VA (Potomac R) -- see
http://www.roadstot­hefuture.com/14th_St­reet_Bridge.html (bridge is
still a drawbridge but has been rendered inoperable)
Apr 30, 2005

6.3.8


Q: Why are there Interstate highways in Hawaii? Are there plans for
Interstates in Alaska or Puerto Rico? Are there any freeways in Alaska
or Puerto Rico?

A: The Hxx Interstates were approved by AASHTO when Hawaii became a
state in 1959 to allow Hawaii to have Interstates (see
http://www.fhwa.dot­.gov/infrastructure/­hawaii.htm and
http://www.hawaiihi­ghways.com/FAQs-page­4.htm#why-Interstate­s ). Even
though Alaska and Hawaii do not connect directly to other states, their
highways fall into the same system as those in the other 48 states, so
while "Interstate" can't be literal, the name is there for consistency.
Alaska and Puerto Rico officially have Axx and PRxx routes,
respectively, but these are unsigned and, in Alaska's case at least,
generally not up to Interstate standards. In 1959, when Alaska became a
state, they asked for funding for fully standard Interstates on the
current corridors plus others, including one to Nome. This was
rejected. In 1981, FHWA added current routes A1-A4 to the Interstate
system as 2 lane rural arterials. The only Alaska Interstate routes
that have been upgraded to freeway are AK 1 (A1) east of downtown
Anchorage to just short of the AK 3 (Interstate A4) junction in Palmer,
and a few miles of AK 1 (Interstate A3) south of downtown Anchorage.
Puerto Rico has many rural and urban freeways (autopistas); most of the
rural freeways are tolled. The AK/HI/PR Interstates do not have an "I-"
preceding them in their abbreviations.
Here is a list of the Ax routes:

A1 follows AK 2 from the Canadian border to Tok Junction and then AK 1
to Anchorage.
A2 follows AK 2 from Tok Junction (AK 1) to Fairbanks.
A3 follows AK 1 from Anchorage to Soldotna.
A4 follows AK 3 from Palmer (AK 1) to Fairbanks.

Aug 17, 2004

6.3.9

Q: What's up with I-585 in Spartanburg, SC?

A: When the I-85 bypass around Spartanburg was built, old I-85 became
BUSINESS I-85. I-585 originally ended at I-85 like it should, but since
new I-85 was built it has not touched I-85.
Another oddity on I-585 is the fact that it is signed for several
blocks past the freeway end in downtown Spartanburg.
In other words, I-585 doesn't extend far enough to I-85 and extends too
far on the other end. See http://www.kurumi.c­om/roads/3di/i585.ht­ml and
http://www.intersta­te-guide.com/i-585_s­c.html . May 28, 2003

6.3.10

Q: Why is the Chicago Skyway no longer I-90?

A: In late 1999, Chicago added a TO banner to all the I-90 reassurance
markers on the city-maintained Skyway. Apparently the city was looking
at old records and realized it was never technically approved as an
interstate (see
http://groups-beta.­google.com/group/mis­c.transport.road/msg­/2044938ffca6c8b4
, message ID n9jig-2008991217310­001@chi-pm4-1a-40.th­eramp.net ).
Another strange fact about the Skyway is that it was built as a 10 mile
toll bridge. Illinois law at the time prohibited non-bridge toll roads,
so Chicago had to get it approved as a toll bridge over the Calumet
River.
In early March 2004 a plan to privatize the Skyway was proposed; this
plan was put into action in mid-October 2004. ("For Sale: Chicago
Skyway", Chicago Sun-Times, March 2, 2004; "Overseas investors to lease
Skyway from city", Chicago Tribune, October 15, 2004)
The Skyway has a McDonald's restaurant in the median by the toll plaza.
Related: http://www.n9jig.co­m/tollways.html Oct 21, 2004

6.3.11

Q: Why does I-180 in IL exist?

A: I-180 serves the town of Hennepin, population 707 (2000 census). It
was built to serve LTV steel, a major defense contractor. In the future
it may be extended south to Peoria, but it currently has almost no
traffic. See http://www.kurumi.c­om/roads/3di/i180.ht­ml#180il ,
http://www.n9jig.co­m/gallery/expw.html , and
http://www.intersta­te-guide.com/i-180_i­l.html . May 28, 2003

6.3.12

Q: What happened to I-265 in Nashville?

A: In late 2000, I-65 was rerouted along the former I-265, which
existed between I-24 and I-40 northwest of downtown, to relieve traffic
on the former I-40/65 multiplex (now I-40 between I-65 and I-24). See
http://www.kurumi.c­om/roads/3di/ix65.ht­ml#265tn and
http://www.intersta­te-guide.com/i-265_t­n.html . May 28, 2003

6.3.13

Q: Are Kentucky's parkways built to Interstate standards?

A: No, according to Carl Dixon, Branch Manager, Division of Planning,
Kentucky Transportation Cabinet. Each of Kentucky's parkways would
require work to reach the standards defined for Interstates. Work that
would be required depends on the parkway; however, the work would
"include more lanes (e.g., the Daniel Boone Parkway), wider median
widths, wider shoulders, reduced grades, smoother curves, improved
interchanges, and possibly several other design details". The Parkways,
however, do allow trucks. The "Parkway" designation stems from the fact
that that's what Kentucky called its toll highways (not all of these
are tolled anymore). I-66 is planned to run along the Cumberland
Parkway and possibly the Boone, Natcher, and Western Kentucky Parkways,
and I-69 is planned to run along the Purchase Parkway and possibly the
Pennyrile and Western Kentucky Parkways (see
http://www.kentucky­roads.com/i-66/ and
http://www.kentucky­roads.com/i-69/ ). Jan 28, 2002

6.3.14

Q: Why do I-17's exit numbers start so high?

A: Until the mid-1980s Arizona used a special system for its mileage --
any route which did not enter Arizona from another state used the
mileage of the route where its southern or western end was for its
point of origin rather than zero (e.g.: If Route 2's southern end was
at Route 1 and Route 1's mileage at the Route 1/Route 2 intersection is
Mile 57, then Route 2's lowest-numbered milemarker would be Mile 57).
I-17 is a special case: Its exit numbers are actually those of the
former longer routing of AZ 69, which branched from US 89 at Mile 201,
since I-17 and AZ 69 were paired early on. AZ 69 has been truncated
since I-17's exits were numbered (see
http://www.arizonar­oads.com/arizona/az6­9.htm ). I-17's exit numbers are
not related to those of I-19 (see 10.3). Feb 20, 2002

6.3.15

Q: What's with the I-465 spur northwest of Indianapolis? What is it
designated?

A: I-865, the east-west I-465 spur which connects I-65 to I-465
northwest of Indianapolis, exists partly because the I-65/I-465
interchange farther south lacks ramps between the north and northwest
(it also has no ramps between the south and southeast). It was formerly
signed as I-465 East eastbound and I-65 North westbound (the I-65/I-465
spur interchange also lacks connections, between the southeast and
east) and was simply considered another part of I-465. It was
renumbered to I-865 in April 2002 and signage was changed beginning in
May 2002. Why it is now called I-865 is thoroughly explained in an
Indiana DOT press release (see
http://www.in.gov/s­erv/presscal?PF=dot&­Clist=6&Elist=52862 ). The spur
also carries US 52, which, while not signposted along most of I-465
(see 3.9.1), is in fact signed along the length of the spur. The
milemarkers on this spur used to start at 900 before it was renumbered.
See also http://www.kurumi.c­om/roads/3di/ix65.ht­ml#465in . Jun 11, 2002

6.3.16

Q: Has there been a proposal to extend eastern I-76 eastward?

A: Not officially. Many laypeople have proposed this extension, which
entails the freeway portion of NJ 42 plus most or all of the Atlantic
City Expressway, but this has not been considered officially due to a
combination of sub-Interstate features, potential confusion, and
disinterest (see
http://groups-beta.­google.com/group/mis­c.transport.road/bro­wse_frm/thread/4a67d­49058462018
). Oct 16, 2003

6.4

Q: Why do people want I-69 extended?

A: The I-69 extension was proposed by businessmen in the early 1990s to
stimulate international trade between Canada, Mexico and the United
States. It would run from Port Huron, Michigan to Brownsville, Texas.
It currently runs from Port Huron to Indianapolis. In Indiana, it was
decided that I-69 will run along a new alignment from Indianapolis to
Evansville (it will probably multiplex with I-465 around Indianapolis)
rather than along I-70, a new southeast bypass of Terre Haute, and an
upgraded US 41. More information is at
http://www.aaroads.­com/high-priority/co­rr18.html ,
http://www.i69info.­com/ , and
http://dmoz.org/Rec­reation/Roads_and_Hi­ghways/Interstate_69­/ . Jul 9,
2003

6.5

Q: What's this I hear about a new Interstate marker?

A: This is a hoax. Basically the rumor was that AASHTO plans to
implement a new shield design by 2007 or earlier. It was a circle in a
square, considered ugly by most.

6.6

Q: Is one mile of each five in the Interstate system required to be
able to act as an emergency landing strip for aircraft?

A: No. See http://www.tfhrc.go­v/pubrds/mayjun00/on­emileinfive.htm
(official) and http://www.snopes.c­om/autos/law/airstri­p.asp . It was
considered briefly ( http://www.fhwa.dot­.gov/infrastructure/­turner.htm
) but never adopted officially. There are unusually-built overpasses
(truss structure) on a straight section of I-75 near the former
Kincheloe Air Force Base (now Chippewa County International Airport) in
the Upper Peninsula of Michigan, leading to speculation that the
Michigan State Highway Department did build I-75 here to accomodate
aircraft. This is purely speculation, however, with no conclusive proof
so far.

Conversely, there was a Cold-War bunker built under I-5 in Seattle, at
the Ravenna Boulevard overpass, by the state of Washington in the early
1960s (see http://www.historyl­ink.org/output.CFM?f­ile_ID=3705 ). Nov 6,
2003

a system in which truck drivers may use a transponder to bypass weigh
stations. For more information go to http://www.prepass.­com/ . Jan 22,
2002

6.8

Q: What is the largest city without an Interstate?

A: It is the consensus of m.t.r that Fresno, CA (2000 pop. 427,652), is
the most populous city in the U.S. without an Interstate within its
boundaries. The closest it has to an Interstate is CA 99, old US 99
(see 7.4.2). (Mesa, AZ, is expected to pass Fresno in population by the
2010 Census - it only has the US 60 freeway and part of the Phoenix
loop system - see 6.3.5 ). The largest cities with only one Interstate
are Austin, TX (2000 pop. 656,562), with I-35, and Colorado Springs, CO
(2000 pop. 360,890), with I-25. El Paso, TX (2000 pop. 563,662) has
only one signposted interstate, I-10, but also has "hidden" I-110 (see
http://www.kurumi.c­om/roads/3di/i110.ht­ml#110tx ). Oct 21, 2004

6.9 Interstate Standards

Interstates have higher standards than basic freeways. While freeways
require grade separation and interchanges in place of at-grade
intersections, Interstates also require, at minimum, 12' wide lanes, 6'
wide shoulders (4' paved - if there are three or more lanes, the left
shoulder should be 12', 10' of it paved), 36' medians in rural areas
and 10' medians in urban or mountainous areas, a design speed of 60 mph
in urban areas and 70 mph in rural areas (with speeds as low as 50 mph
in rugged terrain), acceleration and deceleration lane length to the
current standards of AASHTO (see 4.2), a maximum 6% grade and adequate
right-of-way. (1' equals about 0.30 meter, 1 mile equals about 1.61
kilometers) Exceptions can be granted (such as for the 8% grade on
I-24/US 64 Westbound over Monteagle Mountain, TN, the steepest on the
system - see also Question 12.6), but usually only are for pre-existing
older highways. For more information, see AASHTO's publication DS-4, A
Policy on Design Standards - Interstate System, available here on their
website. See 3.13 for tolls on Interstates.
Many non-Interstates are also built to Interstate standards. Respective
states can request that AASHTO include them in the system if the need
to do so exists (examples: http://www.kurumi.c­om/roads/3di/1970req­.html
). Feb 1, 2005

6.10

Q: Where is the longest stretch between services on an Interstate?

A: Eastern Utah, on I-70 between Green River and Salina (104 miles) --
see http://members.aol.­com/utahhwys/rte070.­htm . Jun 13, 2002

6.10.1

Q: Where is the longest stretch between other Interstates on an
Interstate?

A:
Between Interstates of any type: I-80 in NV/UT, unsigned I-580 to I-215
(511 miles)
Between signposted Interstates: I-80 in CA/NV/UT, I-5 to I-215 (647
miles)
Between 2di's: I-80 in CA/NV/UT, I-5 to I-15 (650 miles)
Mar 24, 2004

6.11 Tunnels

A compilation of Interstate (and other) tunnels and their locations is
at
http://groups-beta.­google.com/group/mis­c.transport.road/bro­wse_frm/thread/7922
Add comment
Marc Fannin 1 July 2005 05:40:46 [ permanent link ]
 *I sincerely apologize if this is a duplicate post*

_______

Here are Sections 5 and 6.

The FAQ in its entirety is at
http://www.roadfan.­com/mtrfaq.ÂÂÂÂÂhtml­
(c. 250KB)

___________________­____________________­____________________­_____________
Marc Fannin|musxf579@ken­t.edu or @hotmail.com| http://www.roadfan.­com/

-------------------­--

5 Websites

Links to road websites are available at
http://dmoz.org/Rec­reation/Roads_and_Hi­ghways/ (alternate URL:
http://roadlinks.cj­b.net/ ),
http://www.aboutvia­.com/ (alternate URL:
http://www.ugcs.cal­tech.edu/~jlin/links­/ ),
http://www.aaroads.­com/kick-off/highway­.html , and
http://www.cahighwa­ys.org/othlinks.html­ .
(All of these are listed at
http://dmoz.org/Rec­reation/Roads_and_Hi­ghways/Directories/ .)

See also the Wikipedia "Road" entry and related subarticles at
http://en.wikipedia­.org/wiki/Roads .

A list of roadgeeks by location is at
http://www.roadfan.­com/roadfan.html .

Apr 3, 2005


-------------------­--------------------­--------------------­--------------------­-

6 The Interstate Highway System

The Interstate Highway System (or, more formally, the Dwight D.
Eisenhower National System of Interstate and Defense Highways) is a
system of divided controlled access highways present in every state as
well as DC and PR. It has more than 45,000 miles to its credit. A
complete list is found at http://www.ihoz.com­/interstates.html (1 and 2
digit) and http://www.kurumi.c­om/roads/3di/ (3 digit), as well as at
http://www.intersta­te-guide.com/ . Information on planned Interstates
and Interstate extensions can be found at
http://www.aaroads.­com/high-priority/ and
http://www.intersta­te-guide.com/future.­html . FHWA's overview of the
system is at http://www.fhwa.dot­.gov/programadmin/in­terstate.html , a
route log is at http://www.fhwa.dot­.gov/reports/routefi­nder/ , and some
history is located throughout
http://www.fhwa.dot­.gov/infrastructure/­history.htm . The U.S. Code of
Federal Regulations lists in Title 23, Appendix A to Subpart A of Part
470, the "Guidance Criteria for Evaluating Requests for Interstate
System Designations Under [Title] 23 [of the] U.S. [Code, now-repealed
Section] 139 (a) and (b)" (for text, see the portion directly after
Section 470.115 in the respective file at
http://www.access.g­po.gov/nara/cfr/wais­idx_04/23cfr470_04.h­tml ).
AASHTO's Interstate policy is at
http://www.traffics­ign.us/inpolicy.html­ . This policy states among
other items that Interstates and U.S. Highways with the same number
should not exist in the same state, although US 24 and I-24 both exist
in IL, and US 80 and I-80 briefly existed in CA until the former was
truncated outside the state (both instances presumedly overlooked due
to the distance between), and three proposed Interstate extensions are
planned to exist in states with the corresponding U.S. route (49 in AR,
69 in TX, 74 in NC - on current signage for the latter's pairing with
US 74, "FUTURE" replaces "INTERSTATE" on the I-74 shields).
Even though these routes are known as being federally-marked routes, it
is actually the states that maintain them in most cases, and other
non-federal-level agencies in the rest. The Interstates have received
federal funding of various percentages of the whole throughout the
history of the system, however (see
http://www.cahighwa­ys.org/itypes.html ). Interstates are automatically
included in the National Highway System (see Question 7.7 ).
There are single-state Interstates (see Question 6.12) - the name
"Interstate" refers to the system as a whole and not to any individual
numbered route.
A ranking subject to interpretation of 2-digit Interstates by
importance is located at http://www.kurumi.c­om/roads/rank2di.htm­l .
For business route information see 3.2. Jun 28, 2005

6.1 Interstate History

See also Section 17.

6.1.1

Q: How did the Interstate Highway System come to be?

A: In 1944, Congress authorized construction of an interstate
expressway system connecting major cities and industrial centers. No
money was involved in the bill. The project never took off until the
awarding of the first contract for I-70 in Missouri, in 1956. North
Dakota was the first state to complete its Interstates. More
information is available at
http://www.tfhrc.go­v/pubrds/summer96/p9­6su10.htm and
http://eisenhower.a­rchives.gov/dl/Inter­stateHighways/Inters­tateHighwaysdocument­s.html
. Jul 10, 2003

6.1.2

Q: What was the first stretch of Interstate to open?

A: The first stretch of Interstate opened under the 1944 Congress act
was I-70 in Kansas, which opened in 1957. More information is at
http://www.tfhrc.go­v/pubrds/summer96/p9­6su18.htm 2000-08-17 15:29:33

6.1.3

Q: What were the original plans for Interstates?

A: The Interstate System's original plans are detailed in a publication
called General location of national system of interstate highways,
including all additional routes at urban areas designated in September,
1955, commonly known as the "Yellow Book". Go to
http://www.roadfan.­com/intreg.html#yell­owbk for much more information
including maps. Feb 25, 2002

6.2 Interstate Numbering

There's a very strict plan for numbering Interstate routes. The one and
two-digit routes are the mainlines, with the even numbered routes going
east-west, and the odd routes going north-south. The even routes'
numbers increase as you go north, with the odd Interstate roads
increasing to the east. The major routes end in 0 or 5. As for
three-digit interstates, those that both start and end at a 2-digit
route get an even first digit, while those not connected to the
Interstate system at their end or ends have an odd first digit.
Exceptions to this occur usually when a state has depleted its
respective choices for 3-digit Interstates. If a 3-digit Interstate has
another 3-digit Interstate branching from it (a "grandchild"), then the
numbering for the second-generation highway is the same as for the
first-generation one. In the field are I-105 CA, I-235 KS, I-444 OK,
I-370 MD, I-175/375 FL, I-278/478/678/878 NJ/NY, I-579 PA,
I-280/380/980 CA, I-190 MA, I-590/990 NY, I-495 NY, I-695 DC, and I-795
MD (each intersects with another 3di with a common "root" but not with
its 2di parent). I-195 NJ also used to be one but it now intersects
I-95 directly. For more on numbering see the FHWA site at
http://www.fhwa.dot­.gov/programadmin/in­terstate.html#Inters­tate_Numbering
. Apr 14, 2004

6.2.1 Letter Suffixes

6.2.1.1

Q: What happened to letter extensions on Interstate highways?

A: AASHTO eliminated them in 1980 and told state DOTs to think of other
numbers. Two still remain on I-35. I-15E in California stayed until
1983 (see 6.2.1.3). Jan 18, 2002

6.2.1.2

Q: Why does I-35 split in Dallas and Minneapolis?

A: As stated in the previous question, some Interstates once carried
letter suffixes. All but three were changed in 1980, and one of those
(I-15E in CA) was gone by 1983. The remaining two are the I-35 splits
in Dallas and Minneapolis, which remain because there was no consensus
on what the new numbers would be. The smaller cities, St. Paul and Fort
Worth, did not want their Interstate highways "demoted" to 3di's. Jul
9, 2003

6.2.1.3

Q: What are/were all the suffixed interstates?

A:

Actually existed

I-5W (CA) -- I-505, I-80, I-580, I-205 (see
http://www.cahighwa­ys.org/001-008.html#­005 for details)
I-15E (CA) -- I-215 (see http://www.cahighwa­ys.org/009-016.html#­015 ,
section 2, for details)
I-15W (ID) -- western I-86
I-24W (MO/TN) -- I-155 and US 412
I-35W/I-35E still exists in TX and MN (see 6.2.1.2)
I-35W (KS) -- I-135
I-59B (AL) -- I-459 (Note: "59B" was chosen through a system of
placeholder numbers using "A", "B", etc., as opposed to "B" meaning
"bypass")
I-70N/I-70S (MD) -- I-70/I-270
I-70S (PA) -- I-70 between I-79 and I-76
I-75E (FL) -- I-75 between I-275 termini
I-80N (OR/ID/UT) -- western I-84
I-80N (IA) -- I-680 east of I-29
I-80N (OH) -- I-80/90, I-90, I-490, I-480, and OH 14 between US 250
near Norwalk and I-76 near Ravenna
I-80S (CO/NE) -- western I-76
I-80S (OH/PA/NJ) at first used today's I-76 in OH and PA and I-276 in
PA; later it was rerouted on today's I-76 and I-676 through
Philadelphia and Camden rather than around; and later it was truncated
at today's I-376 when I-76 was created along today's I-376 and the PA
Turnpike
(See http://www.roadfan.­com/ohiomaps.html ,
http://www.pahighwa­ys.com/interstates/p­di.html#I80S , and
http://www.fhwa.dot­.gov/infrastructure/­i76.htm for details on the
OH/PA/NJ I-80N/I-80 and I-80/I-80S)
I-81E (PA) -- I-380
I-180N (ID) -- I-184 in Boise; all other spurs of suffixed 2dis were
non-suffixed


Planned but never signed

The sources for these are the 1957 and 1958 maps on
http://www.roadfan.­com/5758int.html -- see 6.1.3 for more details

I-5E (CA) -- I-5 between I-5W termini (see above)
I-80N (PA/NJ) -- I-78
I-80S (PA) -- I-76 east of Harrisburg
I-81S (PA) -- I-81E (see above)
I-82N (ID) -- I-15W (see above)
I-82S (ID/UT) -- I-80N between I-15W (see above) and I-15
I-90N (NY) -- I-190
I-94N (MI) -- I-196 (now I-96 west of Grand Rapids)
I-95E (RI/MA) -- I-195 (pre-Interstate plans called it US 6)

Dec 4, 2004

6.2.2

Q: Why the heck does I-99 have such a weird number?

A: This has been one of the most contentious questions or topics in the
newsgroup. Unlike other interstate highways, which have their numbers
assigned by AASHTO, I-99's number was assigned in a piece of
appropriations legislation sponsored by former Rep. Bud Shuster
(R-Pa.), through whose district the highway ran.

Many of the regulars on m.t.r take issue with this highway designation
because:

1) Its number was written into law, as described above;

2) Its number is out of place--a highway designated as I-99 should run
right along the Atlantic coast; and

3) From its length (under 70 miles), location (in an area where all the
available 2di designations are already being used), route (basically, a
spur from I-76 to the Altoona/State College area, at least until it
connects to I-80), and the fact that it doesn't come close to any
interstate other than I-76, an odd 3di designation (such as I-576)
would be more appropriate.

As a side note, for now I-99 also has the distinction of being the only
2 digit interstate that does not have a direct interchange with any
other interstate.

More information is available at
http://www.pahighwa­ys.com/interstates/I­99.html . Oct 3, 2004

6.2.3

Q: What is I-238?

A: Interstate 238 is a 2-mile freeway on the east side of San Francisco
Bay, California. It is not numbered according to the regular Interstate
numbering conventions; rather, it was an extension of CA 238. There is
no I-38. More information is at http://www.gbcnet.c­om/roads/I-238/ .
May 28, 2002

6.2.4

Q: Why are there two Interstates 76, 84, 86 and 88?

A: All duplicates but 86 arose around the time when most letter
suffixes on Interstates were removed, though not all replaced a
suffixed Interstate designation. Eastern I-86 (see 6.3.6) was recently
added because there were no other choices that would fit. At one time,
an eastern I-86 existed from Hartford, CT to I-90 in MA; this is now
part of I-84 (see http://www.kurumi.c­om/roads/ct/i86.html­ ). There were
also two I-39s, but I-39 is now signed along I-90 between the two
sections (see http://www.intersta­te-guide.com/i-039.h­tml ). There are
technically two I-74s, but these are planned to be connected, unlike
the other duplicates (see Question 6.3.4 ). May 6, 2005

6.2.5

Q: Which 3di spurs go both directions from a parent?

A: I-305 CA (hidden), I-516 GA, I-540 AR (small overlap with I-40),
I-170 MO (crosses I-70, ends at I-270), I-580 CA (small overlap with
I-80), I-181 TN (to be replaced by I-26), I-390 NY (crosses I-90, ends
at I-490), I-394 MN (crosses I-94, ends at I-494), I-595 FL; future:
I-710 CA, I-355 IL, I-195 NJ Jan 29, 2004

6.3 Oddities

6.3.1

Q: What happens to I-95 in NJ?

A: The short explaination is the "NIMBY factor". Residents of the
Princeton and New Brunswick, NJ, areas managed to kill a section of
I-95 through their towns in the early 1980s; the NJ Turnpike also
opposed it as it would provide an alternate to the toll road. There has
been a gap ever since. On the NJ Turnpike, the I-95 signs disappear.
There is a plan to build an interchange connecting the existing I-95
with the PA Turnpike northeast of Philadelphia, where they currently
cross but do not have an interchange. The new routing would follow the
PA Turnpike connector from the NJ Turnpike across the Delaware River to
the new interchange, where it would resume its old route. This
interchange should be complete around 2008. More information is
available at http://www.njfreewa­ys.com/Interstate_95­_Gap.html ,
http://www.nycroads­.com/roads/I-95_NJ/ , and
http://www.paturnpi­ke.com/i95/ . This will complete the gap between New
York City and Philadelphia, but will not provide easy access to I-287
from Philadelphia for bypassing New York City as original I-95 would
have.
Some propose rerouting I-95 on the NJ Turnpike all the way to the
Delaware Memorial Bridge and I-295; this is how most through traffic
goes anyway. Many people have a problem with this because it would
bypass Philadelphia. Sep 30, 2004

6.3.1.1

Q: Are I-95's exit numbers between I-80 and NY an extension of I-80's?

A: No. Those numbers are based on the original mileage of I-95 in NJ
including the unbuilt portion mentioned above in 6.3.1 (see the
relevant section of http://www.nycroads­.com/roads/I-95_NJ/ ). Sep 30,
2004

6.3.2

Q: Why do some Interstates, such as I-180 in WY, have traffic lights or
at-grade intersections?

A: Usually Interstates are not allowed to have any cross traffic. In
fact at-grade intersections have kept the new I-86 in New York from
extending further east. But in these cases, AASHTO granted variances
because there was no other reasonable way to build them.
Wyoming I-180 is the only Interstate with no freeway portions. There
are three stoplights. Why was it commissioned in the first place? The
state of Wyoming wanted an Interstate serving downtown Cheyenne. It was
to be freeway, but that idea was rejected. More information is at
http://www.rockymou­ntainroads.com/wyomi­ng/i-180.html
I-676 in Philadelphia, PA has some traffic lights between the Vine St
Expressway and the Ben Franklin Bridge. Construction of a freeway
connection would impact several historic landmarks. There is some doubt
among roadgeeks as to whether I-676 actually goes this way; the
official PennDOT maps label the freeway connection to I-95 as 0676 and
put US 30 on the Ben Franklin Bridge. There is an I-676 shield on the
county map, but shields reflect actual signage, not internal
designations (as the 0676 does). NJDOT however takes I-676 over the
bridge officially and in signage. (See
http://www.pahighwa­ys.com/interstates/I­676.html)
I-78 in Jersey City, NJ runs along a one-way pair of surface streets
between the end of the Turnpike Extension and the Holland Tunnel. I-78
ends just across the border in Manhattan, New York City, so it could be
truncated, but hasn't been. NJ 139 also runs along those streets, as if
NJDOT were prepared for truncation. FHWA, NJDOT, and NYSDOT all
officially refer to these last few miles as I-78. (See also 12.2 )
I-70 in Breezewood, PA is the most famous of these. It runs along a
short section of US 30 lined with businesses between the north-south
free portion of I-70 and the Turnpike connection. It would be fairly
easy to construct direct ramps, but the businesses have been successful
in blocking them. Some think the influential congressman Bud Shuster
has helped block the ramps. (See 3.1 above)
I-585 in Spartanburg, SC is signed past the end of the freeway past
several traffic lights. It is unknown why; the road is also US 176.
(See 6.3.9)
I-690 at the NY State Fairgrounds in Syracuse has a pedestrian crossing
that only functions during the NY State Fair. Because this is only in
operation for a small period of time, it is not worth it to build an
overpass.
I-8, I-10 and I-17 in AZ, I-40 in NC, I-10 and I-40 in W. TX, and I-40
in NM have some at-grade intersections for forest, farm, and ranch
access (see http://www.arizonar­oads.com/wrong/). Most of these highways
were built directly over a pre-existing rural two-lane road, so this is
the only access for many of these properties. Interchanges would not be
worth the expense due to the extremely low traffic which these
intersecting roads carry (some in fact are private).
AK Interstates have signals, but that is because those Interstate
designations are "hidden" along state highways which are usually
surface roads with at-grade intersections (see Question 6.3.8 ).

Several other interstates end at traffic lights, but this is perfectly
OK as long as this is not a 3di's only connection to its parent or an
even 3di's only connection to another interstate at one end.
One example of this that is often brought up is I-587 is Kingston, NY;
this connects to the I-87 ramp via a traffic circle. However, a traffic
circle is somewhat up to standards; there is no cross traffic.
In fact there is a case of a 3DI not meeting its parent; the
abovementioned I-585 in Spartanburg, SC ends at Business Loop I-85,
which is the old I-85 (and is a freeway, but not up to full interstate
standards). It continues to I-85 (bypass) as 4 lane US 176, which is
due for upgrades soon. (See 6.3.9)
I-65 in NW IN formerly had a traffic light installed in 1980 at the IN
Toll Road (I-90) connection at the north end (map at
http://terraserver-­usa.com/image.aspx?t­=4&s=11&z=16&x=1186&­y=11510&w=3
); this was considered by INDOT to be mainline I-65 (
http://www.in.gov/d­ot/div/technology/in­terchanges/I65/is262­.pdf - note
that this diagram shows the rail crossing just north of the signalized
intersection as active; it actually was abandoned by the time I-65 was
extended northward to US-12/20) but was not really the same case of a
traffic light on an Interstate as other examples because the section
north of this signal functioned more like a ramp pair, and was probably
considered one by AASHTO. This has been replaced by conventional
grade-separated freeway ramps.
I-291 in Springfield, MA, has an access point at I-90/MA Turnpike
similar to the former I-65/I-90 junction cited above, albeit with a
more simple design (
http://terraserver-­usa.com/image.aspx?T­=4&S=10&Z=18&X=3514&­Y=23353&W=3
).

Several tunnels on the system have signals at their portals, either to
stop unwanted vehicles from entering (too tall, too heavy, too wide,
hazardous material carrier) or for traffic capacity control.

Question 6.3.7 deals with drawbridges on Interstates, which have
traffic lights but no cross traffic.

Railroad crossings:
The Interstate highway specifications do not permit railroad grade
crossings. A few did exist before, but all have either been grade
separated or had the tracks removed. However, a number of crossings do
still exist on some non-Interstate highways with controlled access. In
many of these cases, the crossing is classified as "Exempt" by the
particular state, meaning that vehicles normally required to stop at
railroad crossings, such as vehicles carrying hazardous material and
school buses, can continue through without stopping. Instead, all
trains are required to send a flagman to clear the highway traffic
before it may proceed. These crossings are rarely busy railroad
mainlines, as they tend to be lightly-used or even disused industrial
spurs. Exempt crossings are noted with a tab on the advance RxR warning
sign post and/or on the crossbuck post itself (see
http://mutcd.fhwa.d­ot.gov/HTM/2003r1/pa­rt8/part8b.htm#secti­on8B05 ).

Former crossings on Interstates:
I-65 north end in IN (see above). Abandoned, then interchange
reconstructed.
I-87 Adirondack Northway, NY, near the Mohawk River. This line was
apparently already up for abandonment with the now-defunct Interstate
Commerce Commission when the Interstate was being built, so it did not
pay to build an overpass that would be useless in a few years.
I-94 near Ypsilanti, MI. Now abandoned. This same line used to cross US
23 at-grade as well.
I-94 near Albion, MI. Now abandoned.
I-395 in N. VA (Shirley Highway) near Glebe Rd. Crossing dismantled
when the Washington & Old Dominion RR folded. Note that this was while
it had its pre-Interstate designation (VA 350).

Existing crossings on non-Interstate controlled-access highways [* -
Exempt]: US-1, Edison, NJ (Jersey Freeway - see 3.14); US-4 near
Rutland, VT; US-12/14/18/151, Madison, WI; US-30/250, Wooster, OH*;
US-60, Springfield, MO; US-63, Columbia, MO; US 151, Beaver Dam, WI;
US-151, Waupun, WI; US-301, Rocky Mount, NC; US-322 between Harrisburg
and Hershey, PA*; NY-49 near Rome*; OH-7, north of Martins Ferry;
Atlantic City-Brigantine Connector, NJ*

Other former grade crossings on major divided highways: US-1, Danvers,
MA; US-3, Billerica, MA; US-4, Portsmouth, NH; US-6, Denver, CO;
US-12/14/18/151, Madison, WI (2 others in addition to the current one);
US-23 south of Dundee, MI (and others); US-64, Tulsa, OK (2); US-131,
Kalamazoo, MI; MA-2, Concord; NY-17 (Quickway)/future I-86 near
Middletown, NY

Note: The above question refers to Interstate intersections with roads
which carry general traffic and not roadways such as maintenance roads
(intersections between these and freeways are common throughout the
U.S.). Jun 16, 2005

6.3.3

Q: Where was the Embarcadero Freeway and why was it torn down?

A: The Embarcadero Freeway, I-480, would have connected the Bay Bridge
to the Golden Gate Bridge in San Francisco, carrying mostly local
traffic. The first section north from I-80 was built. Most San
Francisco residents hated it because it blocked the view of the
waterfront from the other side. After a 1989 earthquake almost made it
collapse, it was permanently closed and torn down. The same thing
happened to the northern half and most of the upper deck of the Central
Skyway (US 101). Across the Bay in Oakland, part of the Cypress Freeway
(I-880) actually collapsed, killing some motorists. This double decker
freeway was torn down and rebuilt on a new alignment; the old alignment
is now a wide boulevard with a park in the middle.
More information is at http://www.cahighwa­ys.org/371-480.html#­480 and
http://www.kurumi.c­om/roads/3di/i480.ht­ml#480ca . Apr 9, 2004

6.3.4

Q: Why are these I-73 and I-74 signs popping up in North Carolina?

A: Interstate 73 and the 74 extension are specified in the ISTEA
legislation. I-73 will go from Sault Ste. Marie, Michigan to Myrtle
Beach, South Carolina, while the 74 extension will head east from its
present Cincinnati, Ohio terminus to Portsmouth, Ohio and be mostly
multiplexed with 73 south of there. A North Carolina portion south of
Greensboro was already freeway, so they installed signs there. Some
states are reluctant to build the new highway, specifically Ohio. More
information is at http://www.aaroads.­com/high-priority/co­rr05.html
2000-08-11 19:10:26

6.3.5

Q: Why are there freeway loops in Phoenix?

A: The loop freeways are not Interstates because they are funded by a
1/2 cent sales tax paid by county residents, not by Federal money. If
these freeways had waited for inclusion in the Interstate system, they
may have been delayed for years, or never been built at all. More
information is at http://www.arizonar­oads.com/urban/ . Jan 15, 2002

6.3.6 What is the new I-86?

The eastern I-86, the newest 2di, runs from just outside Erie, PA, to
East Corning, NY, along state route 17, the Southern Tier Expressway.
The move was designed to spurt economic development in the Elmira and
Binghamton areas. This part was designated in late 1999; it is planned
to extend east to I-87 at Harriman once the at-grade intersections are
eliminated. More information is at
http://www.aaroads.­com/high-priority/co­rr36.html Apr 8, 2002

6.3.6.1

Q: Does it really dip into Pennsylvania?

A: Yes, it does. Exit 60 (US 220) is entirely in Pennsylvania, and the
dip is complete with "STATE BORDER" signs. However, New York maintains
it. Maps: http://www.empirest­ateroads.com/maps/wa­verly.jpg ,
http://terraserver-­usa.com/image.aspx?S­=12&T=2&X=466&Y=5813­&Z=18&W=2 By
the way, this is not part of I-86 yet. Sep 2, 2003

6.3.7

Q: Where are all the drawbridges on the Interstate system?

A: These all had to get variances from FHWA to be approved into the
interstate system.
I-5, OR/WA (Columbia R) -- see
http://www.bizave.c­om/cgi-bin/photoalbu­m.cgi?photoalbum=pdx­bridges&slidetag=Int­erstate
and http://www.columbia­n.com/reflections/br­idge.cfm (this is planned to
be replaced - information at http://www.columbia­rivercrossing.org/ )
I-64, VA (Elizabeth R) -- see
http://www.roadstot­hefuture.com/I64_VA_­Desc.html or
http://www.aaroadtr­ips.com/hampton_road­s.html
I-95/495, VA/DC/MD (Potomac R); see
http://www.roadstot­hefuture.com/Woodrow­_Wilson_Bridge.html (this is
being replaced by a higher drawbridge - information at
http://www.wilsonbr­idge.com/ ) See also 12.2
I-110, MS (Back Bay) -- see http://southeastroa­ds.com/i-110_ms.html­
I-264, VA (Elizabeth R) -- see
http://www.roadstot­hefuture.com/I264_VA­_Desc.html or
http://www.aaroadtr­ips.com/hampton_road­s.html
I-278, NY (Bronx R) -- see http://www.nycroads­.com/roads/bruckner/­
I-280, NJ (Passaic R) -- see http://www.nycroads­.com/roads/I-280_NJ/­
I-280, OH (Maumee R) -- see http://www.roadfan.­com/toledo.html#prop­
(this is being replaced by a fixed span - information at
http://www.lookupto­ledo.org/)
I-695, MD (Curtis Cr) -- see
http://www.roadstot­hefuture.com/Balt_Ou­ter_Harbor.html

Former drawbridges replaced by fixed spans:
I-75, MI (Saginaw R) -- see
http://www.michigan­highways.org/indepth­/zilwaukee.html
I-95, FL (St. Johns R) -- see
http://www.dot.stat­e.fl.us/structures/b­otm/fullerwarren/ful­lerwarren.htm
I-95, NY (Hutchinson R) -- see
http://www.nycroads­.com/roads/new-engla­nd/
I-395 (originally I-95), DC/VA (Potomac R) -- see
http://www.roadstot­hefuture.com/14th_St­reet_Bridge.html (bridge is
still a drawbridge but has been rendered inoperable)
Apr 30, 2005

6.3.8


Q: Why are there Interstate highways in Hawaii? Are there plans for
Interstates in Alaska or Puerto Rico? Are there any freeways in Alaska
or Puerto Rico?

A: The Hxx Interstates were approved by AASHTO when Hawaii became a
state in 1959 to allow Hawaii to have Interstates (see
http://www.fhwa.dot­.gov/infrastructure/­hawaii.htm and
http://www.hawaiihi­ghways.com/FAQs-page­4.htm#why-Interstate­s ). Even
though Alaska and Hawaii do not connect directly to other states, their
highways fall into the same system as those in the other 48 states, so
while "Interstate" can't be literal, the name is there for consistency.
Alaska and Puerto Rico officially have Axx and PRxx routes,
respectively, but these are unsigned and, in Alaska's case at least,
generally not up to Interstate standards. In 1959, when Alaska became a
state, they asked for funding for fully standard Interstates on the
current corridors plus others, including one to Nome. This was
rejected. In 1981, FHWA added current routes A1-A4 to the Interstate
system as 2 lane rural arterials. The only Alaska Interstate routes
that have been upgraded to freeway are AK 1 (A1) east of downtown
Anchorage to just short of the AK 3 (Interstate A4) junction in Palmer,
and a few miles of AK 1 (Interstate A3) south of downtown Anchorage.
Puerto Rico has many rural and urban freeways (autopistas); most of the
rural freeways are tolled. The AK/HI/PR Interstates do not have an "I-"
preceding them in their abbreviations.
Here is a list of the Ax routes:

A1 follows AK 2 from the Canadian border to Tok Junction and then AK 1
to Anchorage.
A2 follows AK 2 from Tok Junction (AK 1) to Fairbanks.
A3 follows AK 1 from Anchorage to Soldotna.
A4 follows AK 3 from Palmer (AK 1) to Fairbanks.

Aug 17, 2004

6.3.9

Q: What's up with I-585 in Spartanburg, SC?

A: When the I-85 bypass around Spartanburg was built, old I-85 became
BUSINESS I-85. I-585 originally ended at I-85 like it should, but since
new I-85 was built it has not touched I-85.
Another oddity on I-585 is the fact that it is signed for several
blocks past the freeway end in downtown Spartanburg.
In other words, I-585 doesn't extend far enough to I-85 and extends too
far on the other end. See http://www.kurumi.c­om/roads/3di/i585.ht­ml and
http://www.intersta­te-guide.com/i-585_s­c.html . May 28, 2003

6.3.10

Q: Why is the Chicago Skyway no longer I-90?

A: Actually, according to FHWA, it still is. In late 1999, Chicago
added a TO banner to all the I-90 reassurance markers on the
city-maintained Skyway. Apparently the city was looking at old records
and realized it was never technically approved as an interstate (see
http://groups-beta.­google.com/group/mis­c.transport.road/msg­/2044938ffca6c8b4
, message ID n9jig-2008991217310­001@chi-pm4-1a-40.th­eramp.net ).
However, in 2005, FHWA rebutted by saying that I-90 is and always has
been on the Skyway, at least since the I-90 and I-94 designations have
been as they have since 1964 (see
http://www.tollroad­snews.com/cgi-bin/a.­cgi/XeXDlOhBEdmcEIJ6­1nsxIA ,
6/28/05).
Another strange fact about the Skyway is that it was built as a 10 mile
toll bridge. Illinois law at the time prohibited non-bridge toll roads,
so Chicago had to get it approved as a toll bridge over the Calumet
River.
In early March 2004 a plan to privatize the Skyway was proposed; this
plan was put into action in mid-October 2004. ("For Sale: Chicago
Skyway", Chicago Sun-Times, March 2, 2004; "Overseas investors to lease
Skyway from city", Chicago Tribune, October 15, 2004)
The Skyway has a McDonald's restaurant in the median by the toll plaza.
Related: http://www.n9jig.co­m/tollways.html Jun 30, 2005

6.3.11

Q: Why does I-180 in IL exist?

A: I-180 serves the town of Hennepin, population 707 (2000 census). It
was built to serve LTV steel, a major defense contractor. In the future
it may be extended south to Peoria, but it currently has almost no
traffic. See http://www.kurumi.c­om/roads/3di/i180.ht­ml#180il ,
http://www.n9jig.co­m/gallery/expw.html , and
http://www.intersta­te-guide.com/i-180_i­l.html . May 28, 2003

6.3.12

Q: What happened to I-265 in Nashville?

A: In late 2000, I-65 was rerouted along the former I-265, which
existed between I-24 and I-40 northwest of downtown, to relieve traffic
on the former I-40/65 multiplex (now I-40 between I-65 and I-24). See
http://www.kurumi.c­om/roads/3di/ix65.ht­ml#265tn and
http://www.intersta­te-guide.com/i-265_t­n.html . May 28, 2003

6.3.13

Q: Are Kentucky's parkways built to Interstate standards?

A: No, according to Carl Dixon, Branch Manager, Division of Planning,
Kentucky Transportation Cabinet. Each of Kentucky's parkways would
require work to reach the standards defined for Interstates. Work that
would be required depends on the parkway; however, the work would
"include more lanes (e.g., the Daniel Boone Parkway), wider median
widths, wider shoulders, reduced grades, smoother curves, improved
interchanges, and possibly several other design details". The Parkways,
however, do allow trucks. The "Parkway" designation stems from the fact
that that's what Kentucky called its toll highways (not all of these
are tolled anymore). I-66 is planned to run along the Cumberland
Parkway and possibly the Boone, Natcher, and Western Kentucky Parkways,
and I-69 is planned to run along the Purchase Parkway and possibly the
Pennyrile and Western Kentucky Parkways (see
http://www.kentucky­roads.com/i-66/ and
http://www.kentucky­roads.com/i-69/ ). Jan 28, 2002

6.3.14

Q: Why do I-17's exit numbers start so high?

A: Until the mid-1980s Arizona used a special system for its mileage --
any route which did not enter Arizona from another state used the
mileage of the route where its southern or western end was for its
point of origin rather than zero (e.g.: If Route 2's southern end was
at Route 1 and Route 1's mileage at the Route 1/Route 2 intersection is
Mile 57, then Route 2's lowest-numbered milemarker would be Mile 57).
I-17 is a special case: Its exit numbers are actually those of the
former longer routing of AZ 69, which branched from US 89 at Mile 201,
since I-17 and AZ 69 were paired early on. AZ 69 has been truncated
since I-17's exits were numbered (see
http://www.arizonar­oads.com/arizona/az6­9.htm ). I-17's exit numbers are
not related to those of I-19 (see 10.3). Feb 20, 2002

6.3.15

Q: What's with the I-465 spur northwest of Indianapolis? What is it
designated?

A: I-865, the east-west I-465 spur which connects I-65 to I-465
northwest of Indianapolis, exists partly because the I-65/I-465
interchange farther south lacks ramps between the north and northwest
(it also has no ramps between the south and southeast). It was formerly
signed as I-465 East eastbound and I-65 North westbound (the I-65/I-465
spur interchange also lacks connections, between the southeast and
east) and was simply considered another part of I-465. It was
renumbered to I-865 in April 2002 and signage was changed beginning in
May 2002. Why it is now called I-865 is thoroughly explained in an
Indiana DOT press release (see
http://www.in.gov/s­erv/presscal?PF=dot&­Clist=6&Elist=52862 ). The spur
also carries US 52, which, while not signposted along most of I-465
(see 3.9.1), is in fact signed along the length of the spur. The
milemarkers on this spur used to start at 900 before it was renumbered.
See also http://www.kurumi.c­om/roads/3di/ix65.ht­ml#465in . Jun 11, 2002

6.3.16

Q: Has there been a proposal to extend eastern I-76 eastward?

A: Not officially. Many laypeople have proposed this extension, which
entails the freeway portion of NJ 42 plus most or all of the Atlantic
City Expressway, but this has not been considered officially due to a
combination of sub-Interstate features, potential confusion, and
disinterest (see
http://groups-beta.­google.com/group/mis­c.transport.road/bro­wse_frm/thread/4a67d­49058462018
). Oct 16, 2003

6.4

Q: Why do people want I-69 extended?

A: The I-69 extension was proposed by businessmen in the early 1990s to
stimulate international trade between Canada, Mexico and the United
States. It would run from Port Huron, Michigan to Brownsville, Texas.
It currently runs from Port Huron to Indianapolis. In Indiana, it was
decided that I-69 will run along a new alignment from Indianapolis to
Evansville (it will probably multiplex with I-465 around Indianapolis)
rather than along I-70, a new southeast bypass of Terre Haute, and an
upgraded US 41. More information is at
http://www.aaroads.­com/high-priority/co­rr18.html ,
http://www.i69info.­com/ , and
http://dmoz.org/Rec­reation/Roads_and_Hi­ghways/Interstate_69­/ . Jul 9,
2003

6.5

Q: What's this I hear about a new Interstate marker?

A: This is a hoax. Basically the rumor was that AASHTO plans to
implement a new shield design by 2007 or earlier. It was a circle in a
square, considered ugly by most.

6.6

Q: Is one mile of each five in the Interstate system required to be
able to act as an emergency landing strip for aircraft?

A: No. See http://www.tfhrc.go­v/pubrds/mayjun00/on­emileinfive.htm
(official) and http://www.snopes.c­om/autos/law/airstri­p.asp . It was
considered briefly ( http://www.fhwa.dot­.gov/infrastructure/­turner.htm
) but never adopted officially. There are unusually-built overpasses
(truss structure) on a straight section of I-75 near the former
Kincheloe Air Force Base (now Chippewa County International Airport) in
the Upper Peninsula of Michigan, leading to speculation that the
Michigan State Highway Department did build I-75 here to accomodate
aircraft. This is purely speculation, however, with no conclusive proof
so far.

Conversely, there was a Cold-War bunker built under I-5 in Seattle, at
the Ravenna Boulevard overpass, by the state of Washington in the early
1960s (see http://www.historyl­ink.org/output.CFM?f­ile_ID=3705 ). Nov 6,
2003

a system in which truck drivers may use a transponder to bypass weigh
stations. For more information go to http://www.prepass.­com/ . Jan 22,
2002

6.8

Q: What is the largest city without an Interstate?

A: It is the consensus of m.t.r that Fresno, CA (2000 pop. 427,652), is
the most populous city in the U.S. without an Interstate within its
boundaries. The closest it has to an Interstate is CA 99, old US 99
(see 7.4.2). (Mesa, AZ, is expected to pass Fresno in population by the
2010 Census - it only has the US 60 freeway and part of the Phoenix
loop system - see 6.3.5 ). The largest cities with only one Interstate
are Austin, TX (2000 pop. 656,562), with I-35, and Colorado Springs, CO
(2000 pop. 360,890), with I-25. El Paso, TX (2000 pop. 563,662) has
only one signposted interstate, I-10, but also has "hidden" I-110 (see
http://www.kurumi.c­om/roads/3di/i110.ht­ml#110tx ). Oct 21, 2004

6.9 Interstate Standards

Interstates have higher standards than basic freeways. While freeways
require grade separation and interchanges in place of at-grade
intersections, Interstates also require, at minimum, 12' wide lanes, 6'
wide shoulders (4' paved - if there are three or more lanes, the left
shoulder should be 12', 10' of it paved), 36' medians in rural areas
and 10' medians in urban or mountainous areas, a design speed of 60 mph
in urban areas and 70 mph in rural areas (with speeds as low as 50 mph
in rugged terrain), acceleration and deceleration lane length to the
current standards of AASHTO (see 4.2), a maximum 6% grade and adequate
right-of-way. (1' equals about 0.30 meter, 1 mile equals about 1.61
kilometers) Exceptions can be granted (such as for the 8% grade on
I-24/US 64 Westbound over Monteagle Mountain, TN, the steepest on the
system - see also Question 12.6), but usually only are for pre-existing
older highways. For more information, see AASHTO's publication DS-4, A
Policy on Design Standards - Interstate System, available here on their
website. See 3.13 for tolls on Interstates.
Many non-Interstates are also built to Interstate standards. Respective
states can request that AASHTO include them in the system if the need
to do so exists (examples: http://www.kurumi.c­om/roads/3di/1970req­.h
Add comment
Guest 1 July 2005 16:37:07 [ permanent link ]
 6.2.5 --
I-181 no longer qualifies...
I-526 Charleston, SC is omitted...

regards-
Mapmikey

Add comment
Guest 1 July 2005 21:03:33 [ permanent link ]
 mapmikey@gmail.com wrote:> 6.2.5 --> I-181 no longer qualifies...> I-526 Charleston, SC is omitted...>
regards-> Mapmikey

I-385 Greenville, SC is also omitted.

Add comment
Guest 2 July 2005 06:43:13 [ permanent link ]
 

ranierb1187@yahoo.c­om wrote:> mapmikey@gmail.com wrote:> > 6.2.5 --> > I-181 no longer qualifies...> > I-526 Charleston, SC is omitted...> >
regards-> > Mapmikey>
I-385 Greenville, SC is also omitted.

D'oh!

As is I-185 Greenville

Mapmikey

Add comment
Marc Fannin 29 July 2005 00:10:27 [ permanent link ]
 ["500" Error from Google - let's try again and hope the other try isn't
stuck somewhere eventually to be "broken loose"]

___

Here are Sections 5 and 6.

The FAQ in its entirety is at
http://www.roadfan.­com/mtrfaq.ÂÂÂÂÂhtml­
(c. 275KB)

___________________­____________________­____________________­_____________
Marc Fannin|musxf579@ken­t.edu or @hotmail.com| http://www.roadfan.­com/

-------------------­--

5 Websites

Links to road websites are available at
http://dmoz.org/Rec­reation/Roads_and_Hi­ghways/ (alternate URL:
http://roadlinks.cj­b.net/ ),
http://www.aboutvia­.com/ (alternate URL:
http://www.ugcs.cal­tech.edu/~jlin/links­/ ),
http://www.aaroads.­com/kick-off/highway­.html , and
http://www.cahighwa­ys.org/othlinks.html­ .
(All of these are listed at
http://dmoz.org/Rec­reation/Roads_and_Hi­ghways/Directories/ .)

See also the Wikipedia "Road" entry and related subarticles at
http://en.wikipedia­.org/wiki/Roads .

A list of roadgeeks by location is at
http://www.roadfan.­com/roadfan.html .

Apr 3, 2005


-------------------­--------------------­--------------------­--------------------­-

6 The Interstate Highway System

The Interstate Highway System (or, more formally, the Dwight D.
Eisenhower National System of Interstate and Defense Highways) is a
system of divided controlled access highways present in every state as
well as DC and PR. It has more than 45,000 miles to its credit. A
complete list is found at http://www.ihoz.com­/interstates.html (1 and 2
digit) and http://www.kurumi.c­om/roads/3di/ (3 digit), as well as at
http://www.intersta­te-guide.com/ . Information on planned Interstates
and Interstate extensions can be found at
http://www.aaroads.­com/high-priority/ and
http://www.intersta­te-guide.com/future.­html . FHWA's overview of the
system is at http://www.fhwa.dot­.gov/programadmin/in­terstate.html and a
route log is at http://www.fhwa.dot­.gov/reports/routefi­nder/ . See
Question 6.1 for Interstate history. The U.S. Code of Federal
Regulations lists in Title 23, Appendix A to Subpart A of Part 470, the
"Guidance Criteria for Evaluating Requests for Interstate System
Designations Under [Title] 23 [of the] U.S. [Code, now-repealed
Section] 139 (a) and (b)" (for text, see the portion directly after
Section 470.115 in the respective file at
http://www.access.g­po.gov/nara/cfr/wais­idx_04/23cfr470_04.h­tml ).
AASHTO's Interstate policy is at
http://www.traffics­ign.us/inpolicy.html­ . This policy states among
other items that Interstates and U.S. Highways with the same number
should not exist in the same state, although US-24 and I-24 both exist
in IL, and US-80 and I-80 briefly existed in CA until the former was
truncated outside the state (both instances presumedly overlooked due
to the distance between), and three proposed Interstate extensions and
one new Interstate are planned to exist in states with the
corresponding U.S. route (41 in WI, 49 in AR, 69 in TX, 74 in NC - on
current signage for the latter's pairing with US 74, "FUTURE" replaces
"INTERSTATE" on the I-74 shields - see elsewhere in Section 6 for more
details on each of these).
Even though these routes are known as being federally-marked routes, it
is actually the states that maintain them in most cases, and other
non-federal-level agencies in the rest. The Interstates have received
federal funding of various percentages of the whole throughout the
history of the system, however (see
http://www.cahighwa­ys.org/itypes.html ). Interstates are automatically
included in the National Highway System (see Question 7.7 ).
There are single-state Interstates (see Question 6.12) - the name
"Interstate" refers to the system as a whole and not to any individual
numbered route.
A ranking subject to interpretation of 2-digit Interstates by
importance is located at http://www.kurumi.c­om/roads/rank2di.htm­l .
For business route information see 3.2. Jul 19, 2005

6.1 Interstate History

http://www.fhwa.dot­.gov/infrastructure/­history.htm includes many
historical articles, and http://www.intersta­te50th.org/ has been set up
by AASHTO and includes much historical information. See also Section
17.

Jul 19, 2005
6.1.1

Q: How did the Interstate Highway System come to be?

A: In 1944, Congress authorized construction of an interstate
expressway system connecting major cities and industrial centers. No
money was involved in the bill. The project never took off until the
awarding of the first contract for I-70 in Missouri, in 1956. North
Dakota was the first state to complete its Interstates. More
information is available at
http://www.tfhrc.go­v/pubrds/summer96/p9­6su10.htm and
http://eisenhower.a­rchives.gov/dl/Inter­stateHighways/Inters­tateHighwaysdocument­s.html
. Jul 10, 2003

6.1.2

Q: What was the first stretch of Interstate to open?

A: The first stretch of Interstate opened under the 1944 Congress act
was I-70 in Kansas, which opened in 1957. More information is at
http://www.tfhrc.go­v/pubrds/summer96/p9­6su18.htm 2000-08-17 15:29:33

6.1.3

Q: What were the original plans for Interstates?

A: The Interstate System's original plans are detailed in a publication
called General location of national system of interstate highways,
including all additional routes at urban areas designated in September,
1955, commonly known as the "Yellow Book". Go to
http://www.roadfan.­com/intreg.html#yell­owbk for much more information
including maps. Feb 25, 2002

6.2 Interstate Numbering

There's a very strict plan for numbering Interstate routes. The one and
two-digit routes are the mainlines, with the even numbered routes going
east-west, and the odd routes going north-south. The even routes'
numbers increase as you go north, with the odd Interstate roads
increasing to the east. The major routes end in 0 or 5. As for
three-digit interstates, those that both start and end at a 2-digit
route get an even first digit, while those not connected to the
Interstate system at their end or ends have an odd first digit.
Exceptions to this occur usually when a state has depleted its
respective choices for 3-digit Interstates. If a 3-digit Interstate has
another 3-digit Interstate branching from it (a "grandchild"), then the
numbering for the second-generation highway is the same as for the
first-generation one. In the field are I-105 CA, I-235 KS, I-444 OK,
I-370 MD, I-175/375 FL, I-278/478/678/878 NJ/NY, I-579 PA,
I-280/380/980 CA, I-190 MA, I-590/990 NY, I-495 NY, I-695 DC, and I-795
MD (each intersects with another 3di with a common "root" but not with
its 2di parent). I-195 NJ also used to be one but it now intersects
I-95 directly. For more on numbering see the FHWA site at
http://www.fhwa.dot­.gov/programadmin/in­terstate.html#Inters­tate_Numbering
. Apr 14, 2004

6.2.1 Letter Suffixes

6.2.1.1

Q: What happened to letter extensions on Interstate highways?

A: AASHTO eliminated them in 1980 and told state DOTs to think of other
numbers. Two still remain on I-35. I-15E in California stayed until
1983 (see 6.2.1.3). Jan 18, 2002

6.2.1.2

Q: Why does I-35 split in Dallas and Minneapolis?

A: As stated in the previous question, some Interstates once carried
letter suffixes. All but three were changed in 1980, and one of those
(I-15E in CA) was gone by 1983. The remaining two are the I-35 splits
in Dallas and Minneapolis, which remain because there was no consensus
on what the new numbers would be. The smaller cities, St. Paul and Fort
Worth, did not want their Interstate highways "demoted" to 3di's. Jul
9, 2003

6.2.1.3

Q: What are/were all the suffixed interstates?

A:

Actually existed

I-5W (CA) -- I-505, I-80, I-580, I-205 (see
http://www.cahighwa­ys.org/001-008.html#­005 for details)
I-15E (CA) -- I-215 (see http://www.cahighwa­ys.org/009-016.html#­015 ,
section 2, for details)
I-15W (ID) -- western I-86
I-24W (MO/TN) -- I-155 and US 412
I-35W/I-35E still exists in TX and MN (see 6.2.1.2)
I-35W (KS) -- I-135
I-59B (AL) -- I-459 (Note: "59B" was chosen through a system of
placeholder numbers using "A", "B", etc., as opposed to "B" meaning
"bypass")
I-70N/I-70S (MD) -- I-70/I-270
I-70S (PA) -- I-70 between I-79 and I-76
I-75E (FL) -- I-75 between I-275 termini
I-80N (OR/ID/UT) -- western I-84
I-80N (IA) -- I-680 east of I-29
I-80N (OH) -- I-80/90, I-90, I-490, I-480, and OH 14 between US 250
near Norwalk and I-76 near Ravenna
I-80S (CO/NE) -- western I-76
I-80S (OH/PA/NJ) at first used today's I-76 in OH and PA and I-276 in
PA; later it was rerouted on today's I-76 and I-676 through
Philadelphia and Camden rather than around; and later it was truncated
at today's I-376 when I-76 was created along today's I-376 and the PA
Turnpike
(See http://www.roadfan.­com/ohiomaps.html ,
http://www.pahighwa­ys.com/interstates/p­di.html#I80S , and
http://www.fhwa.dot­.gov/infrastructure/­i76.htm for details on the
OH/PA/NJ I-80N/I-80 and I-80/I-80S)
I-81E (PA) -- I-380
I-180N (ID) -- I-184 in Boise; all other spurs of suffixed 2dis were
non-suffixed


Planned but never signed

The sources for these are the 1957 and 1958 maps on
http://www.roadfan.­com/5758int.html -- see 6.1.3 for more details

I-5E (CA) -- I-5 between I-5W termini (see above)
I-80N (PA/NJ) -- I-78
I-80S (PA) -- I-76 east of Harrisburg
I-81S (PA) -- I-81E (see above)
I-82N (ID) -- I-15W (see above)
I-82S (ID/UT) -- I-80N between I-15W (see above) and I-15
I-90N (NY) -- I-190
I-94N (MI) -- I-196 (now I-96 west of Grand Rapids)
I-95E (RI/MA) -- I-195 (pre-Interstate plans called it US 6)

Dec 4, 2004

6.2.2

Q: Why the heck does I-99 have such a weird number?

A: This has been one of the most contentious questions or topics in the
newsgroup. Unlike other interstate highways, which have their numbers
assigned by AASHTO, I-99's number was assigned in a piece of
appropriations legislation sponsored by former Rep. Bud Shuster
(R-Pa.), through whose district the highway ran.

Many of the regulars on m.t.r take issue with this highway designation
because:

1) Its number was written into law, as described above;

2) Its number is out of place--a highway designated as I-99 should run
right along the Atlantic coast; and

3) From its length (under 70 miles), location (in an area where all the
available 2di designations are already being used), route (basically, a
spur from I-76 to the Altoona/State College area, at least until it
connects to I-80), and the fact that it doesn't come close to any
interstate other than I-76, an odd 3di designation (such as I-576)
would be more appropriate.

As a side note, for now I-99 also has the distinction of being the only
2 digit interstate that does not have a direct interchange with any
other interstate.

More information is available at
http://www.pahighwa­ys.com/interstates/I­99.html . Oct 3, 2004

6.2.3

Q: What is I-238?

A: Interstate 238 is a 2-mile freeway on the east side of San Francisco
Bay, California. It is not numbered according to the regular Interstate
numbering conventions; rather, it was an extension of CA 238. There is
no I-38. More information is at http://www.gbcnet.c­om/roads/I-238/ .
May 28, 2002

6.2.4

Q: Why are there two Interstates 76, 84, 86 and 88?

A: All duplicates but 86 arose around the time when most letter
suffixes on Interstates were removed, though not all replaced a
suffixed Interstate designation. Eastern I-86 (see 6.3.6) was recently
added because there were no other choices that would fit. At one time,
an eastern I-86 existed from Hartford, CT to I-90 in MA; this is now
part of I-84 (see http://www.kurumi.c­om/roads/ct/i86.html­ ). There were
also two I-39s, but I-39 is now signed along I-90 between the two
sections (see http://www.intersta­te-guide.com/i-039.h­tml ). There are
technically two I-74s, but these are planned to be connected, unlike
the other duplicates (see Question 6.3.4 ). May 6, 2005

6.2.5

Q: Which 3di spurs go both directions from a parent?

A: I-305 CA (hidden), I-516 GA, I-526 SC, I-540 AR (small overlap with
I-40), I-170 MO (crosses I-70, ends at I-270), I-580 CA (small overlap
with I-80), I-185 SC (crosses I-85, ends at I-385), I-385 SC, I-390 NY
(crosses I-90, ends at I-490), I-394 MN (crosses I-94, ends at I-494),
I-595 FL; future: I-710 CA, I-355 IL, I-195 NJ; former: I-181 TN (part
south of I-81 was replaced by I-26) Jul 19, 2005

6.3 Oddities

6.3.1

Q: What happens to I-95 in NJ?

A: The short explaination is the "NIMBY factor". Residents of the
Princeton and New Brunswick, NJ, areas managed to kill a section of
I-95 through their towns in the early 1980s; the NJ Turnpike also
opposed it as it would provide an alternate to the toll road. There has
been a gap ever since. On the NJ Turnpike, the I-95 signs disappear.
There is a plan to build an interchange connecting the existing I-95
with the PA Turnpike northeast of Philadelphia, where they currently
cross but do not have an interchange. The new routing would follow the
PA Turnpike connector from the NJ Turnpike across the Delaware River to
the new interchange, where it would resume its old route. This
interchange should be complete around 2008. More information is
available at http://www.njfreewa­ys.com/Interstate_95­_Gap.html ,
http://www.nycroads­.com/roads/I-95_NJ/ , and
http://www.paturnpi­ke.com/i95/ . This will complete the gap between New
York City and Philadelphia, but will not provide easy access to I-287
from Philadelphia for bypassing New York City as original I-95 would
have.
Some propose rerouting I-95 on the NJ Turnpike all the way to the
Delaware Memorial Bridge and I-295; this is how most through traffic
goes anyway. Many people have a problem with this because it would
bypass Philadelphia. Sep 30, 2004

6.3.1.1

Q: Are I-95's exit numbers between I-80 and NY an extension of I-80's?

A: No. Those numbers are based on the original mileage of I-95 in NJ
including the unbuilt portion mentioned above in 6.3.1 (see the
relevant section of http://www.nycroads­.com/roads/I-95_NJ/ ). Sep 30,
2004

6.3.2

Q: Why do some Interstates, such as I-180 in WY, have traffic lights or
at-grade intersections?

A: Usually Interstates are not allowed to have any cross traffic. In
fact at-grade intersections have kept the new I-86 in New York from
extending further east. But in these cases, AASHTO granted variances
because there was no other reasonable way to build them.
Wyoming I-180 is the only Interstate with no freeway portions. There
are three stoplights. Why was it commissioned in the first place? The
state of Wyoming wanted an Interstate serving downtown Cheyenne. It was
to be freeway, but that idea was rejected. More information is at
http://www.rockymou­ntainroads.com/wyomi­ng/i-180.html
I-676 in Philadelphia, PA has some traffic lights between the Vine St
Expressway and the Ben Franklin Bridge. Construction of a freeway
connection would impact several historic landmarks. There is some doubt
among roadgeeks as to whether I-676 actually goes this way; the
official PennDOT maps label the freeway connection to I-95 as 0676 and
put US 30 on the Ben Franklin Bridge. There is an I-676 shield on the
county map, but shields reflect actual signage, not internal
designations (as the 0676 does). NJDOT however takes I-676 over the
bridge officially and in signage. (See
http://www.pahighwa­ys.com/interstates/I­676.html)
I-78 in Jersey City, NJ runs along a one-way pair of surface streets
between the end of the Turnpike Extension and the Holland Tunnel. I-78
ends just across the border in Manhattan, New York City, so it could be
truncated, but hasn't been. NJ 139 also runs along those streets, as if
NJDOT were prepared for truncation. FHWA, NJDOT, and NYSDOT all
officially refer to these last few miles as I-78. (See also 12.2 )
I-70 in Breezewood, PA is the most famous of these. It runs along a
short section of US 30 lined with businesses between the north-south
free portion of I-70 and the Turnpike connection. It would be fairly
easy to construct direct ramps, but the businesses have been successful
in blocking them. Some think the influential congressman Bud Shuster
has helped block the ramps. (See 3.1 above)
I-585 in Spartanburg, SC is signed past the end of the freeway past
several traffic lights. It is unknown why; the road is also US 176.
(See 6.3.9)
I-690 at the NY State Fairgrounds in Syracuse has a pedestrian crossing
that only functions during the NY State Fair. Because this is only in
operation for a small period of time, it is not worth it to build an
overpass.
I-8, I-10 and I-17 in AZ, I-40 in NC, I-10 and I-40 in W. TX, and I-40
in NM have some at-grade intersections for forest, farm, and ranch
access (see http://www.arizonar­oads.com/wrong/). Most of these highways
were built directly over a pre-existing rural two-lane road, so this is
the only access for many of these properties. Interchanges would not be
worth the expense due to the extremely low traffic which these
intersecting roads carry (some in fact are private).
AK Interstates have signals, but that is because those Interstate
designations are "hidden" along state highways which are usually
surface roads with at-grade intersections (see Question 6.3.8 ).

Several other interstates end at traffic lights, but this is perfectly
OK as long as this is not a 3di's only connection to its parent or an
even 3di's only connection to another interstate at one end.
One example of this that is often brought up is I-587 is Kingston, NY;
this connects to the I-87 ramp via a traffic circle. However, a traffic
circle is somewhat up to standards; there is no cross traffic.
In fact there is a case of a 3DI not meeting its parent; the
abovementioned I-585 in Spartanburg, SC ends at Business Loop I-85,
which is the old I-85 (and is a freeway, but not up to full interstate
standards). It continues to I-85 (bypass) as 4 lane US 176, which is
due for upgrades soon. (See 6.3.9)
I-65 in NW IN formerly had a traffic light installed in 1980 at the IN
Toll Road (I-90) connection at the north end (map at
http://terraserver-­usa.com/image.aspx?t­=4&s=11&z=16&x=1186&­y=11510&w=3
); this was considered by INDOT to be mainline I-65 (
http://www.in.gov/d­ot/div/technology/in­terchanges/I65/is262­.pdf - note
that this diagram shows the rail crossing just north of the signalized
intersection as active; it actually was abandoned by the time I-65 was
extended northward to US-12/20) but was not really the same case of a
traffic light on an Interstate as other examples because the section
north of this signal functioned more like a ramp pair, and was probably
considered one by AASHTO. This has been replaced by conventional
grade-separated freeway ramps.
I-291 in Springfield, MA, has an access point at I-90/MA Turnpike
similar to the former I-65/I-90 junction cited above, albeit with a
more simple design (
http://terraserver-­usa.com/image.aspx?T­=4&S=10&Z=18&X=3514&­Y=23353&W=3
).

Several tunnels on the system have signals at their portals, either to
stop unwanted vehicles from entering (too tall, too heavy, too wide,
hazardous material carrier) or for traffic capacity control.

Question 6.3.7 deals with drawbridges on Interstates, which have
traffic lights but no cross traffic.

Railroad crossings:
The Interstate highway specifications do not permit railroad grade
crossings. A few did exist before, but all have either been grade
separated or had the tracks removed. However, a number of crossings do
still exist on some non-Interstate highways with controlled access. In
many of these cases, the crossing is classified as "Exempt" by the
particular state, meaning that vehicles normally required to stop at
railroad crossings, such as vehicles carrying hazardous material and
school buses, can continue through without stopping. Instead, all
trains are required to send a flagman to clear the highway traffic
before it may proceed. These crossings are rarely busy railroad
mainlines, as they tend to be lightly-used or even disused industrial
spurs. Exempt crossings are noted with a tab on the advance RxR warning
sign post and/or on the crossbuck post itself (see
http://mutcd.fhwa.d­ot.gov/HTM/2003r1/pa­rt8/part8b.htm#secti­on8B05 ).

Former crossings on Interstates:
I-65 north end in IN (see above). Abandoned, then interchange
reconstructed.
I-87 Adirondack Northway, NY, near the Mohawk River. This line was
apparently already up for abandonment with the now-defunct Interstate
Commerce Commission when the Interstate was being built, so it did not
pay to build an overpass that would be useless in a few years.
I-94 near Ypsilanti, MI. Now abandoned. This same line used to cross US
23 at-grade as well.
I-94 near Albion, MI. Now abandoned.
I-395 in N. VA (Shirley Highway) near Glebe Rd. Crossing dismantled
when the Washington & Old Dominion RR folded. Note that this was while
it had its pre-Interstate designation (VA 350).

Existing crossings on non-Interstate controlled-access highways [* -
Exempt]: US-1, Edison, NJ (Jersey Freeway - see 3.14); US-4 near
Rutland, VT; US-12/14/18/151, Madison, WI; US-30/250, Wooster, OH*;
US-60, Springfield, MO; US-63, Columbia, MO; US 151, Beaver Dam, WI;
US-151, Waupun, WI; US-301, Rocky Mount, NC; US-322 between Harrisburg
and Hershey, PA*; NY-49 near Rome*; OH-7, north of Martins Ferry;
Atlantic City-Brigantine Connector, NJ*

Other former grade crossings on major divided highways: US-1, Danvers,
MA; US-3, Billerica, MA; US-4, Portsmouth, NH; US-6, Denver, CO;
US-12/14/18/151, Madison, WI (2 others in addition to the current one);
US-23 south of Dundee, MI (and others); US-64, Tulsa, OK (2); US-131,
Kalamazoo, MI; MA-2, Concord; NY-17 (Quickway)/future I-86 near
Middletown, NY

Note: The above question refers to Interstate intersections with roads
which carry general traffic and not roadways such as maintenance roads
(intersections between these and freeways are common throughout the
U.S.). Jun 16, 2005

6.3.3

Q: Where was the Embarcadero Freeway and why was it torn down?

A: The Embarcadero Freeway, I-480, would have connected the Bay Bridge
to the Golden Gate Bridge in San Francisco, carrying mostly local
traffic. The first section north from I-80 was built. Most San
Francisco residents hated it because it blocked the view of the
waterfront from the other side. After a 1989 earthquake almost made it
collapse, it was permanently closed and torn down. The same thing
happened to the northern half and most of the upper deck of the Central
Skyway (US 101). Across the Bay in Oakland, part of the Cypress Freeway
(I-880) actually collapsed, killing some motorists. This double decker
freeway was torn down and rebuilt on a new alignment; the old alignment
is now a wide boulevard with a park in the middle.
More information is at http://www.cahighwa­ys.org/371-480.html#­480 and
http://www.kurumi.c­om/roads/3di/i480.ht­ml#480ca . Apr 9, 2004

6.3.4

Q: Why are these I-73 and I-74 signs popping up in North Carolina?

A: Interstate 73 and the 74 extension are specified in the ISTEA
legislation. I-73 will go from Sault Ste. Marie, Michigan to Myrtle
Beach, South Carolina, while the 74 extension will head east from its
present Cincinnati, Ohio terminus to Portsmouth, Ohio and be mostly
multiplexed with 73 south of there. A North Carolina portion south of
Greensboro was already freeway, so they installed signs there. Some
states are reluctant to build the new highway, specifically Ohio. More
information is at http://www.aaroads.­com/high-priority/co­rr05.html
2000-08-11 19:10:26

6.3.5

Q: Why are there freeway loops in Phoenix?

A: The loop freeways are not Interstates because they are funded by a
1/2 cent sales tax paid by county residents, not by Federal money. If
these freeways had waited for inclusion in the Interstate system, they
may have been delayed for years, or never been built at all. More
information is at http://www.arizonar­oads.com/urban/ . Jan 15, 2002

6.3.6 What is the new I-86?

The eastern I-86, the newest 2di, runs from just outside Erie, PA, to
East Corning, NY, along state route 17, the Southern Tier Expressway.
The move was designed to spurt economic development in the Elmira and
Binghamton areas. This part was designated in late 1999; it is planned
to extend east to I-87 at Harriman once the at-grade intersections are
eliminated. More information is at
http://www.aaroads.­com/high-priority/co­rr36.html Apr 8, 2002

6.3.6.1

Q: Does it really dip into Pennsylvania?

A: Yes, it does. Exit 60 (US 220) is entirely in Pennsylvania, and the
dip is complete with "STATE BORDER" signs. However, New York maintains
it. Maps: http://www.empirest­ateroads.com/maps/wa­verly.jpg ,
http://terraserver-­usa.com/image.aspx?S­=12&T=2&X=466&Y=5813­&Z=18&W=2 By
the way, this is not part of I-86 yet. Sep 2, 2003

6.3.7

Q: Where are all the drawbridges on the Interstate system?

A: These all had to get variances from FHWA to be approved into the
interstate system.
I-5, OR/WA (Columbia R) -- see
http://www.bizave.c­om/cgi-bin/photoalbu­m.cgi?photoalbum=pdx­bridges&slidetag=Int­erstate
and http://www.columbia­n.com/reflections/br­idge.cfm (this is planned to
be replaced - information at http://www.columbia­rivercrossing.org/ )
I-64, VA (Elizabeth R) -- see
http://www.roadstot­hefuture.com/I64_VA_­Desc.html or
http://www.aaroadtr­ips.com/hampton_road­s.html
I-95/495, VA/DC/MD (Potomac R); see
http://www.roadstot­hefuture.com/Woodrow­_Wilson_Bridge.html (this is
being replaced by a higher drawbridge - information at
http://www.wilsonbr­idge.com/ ) See also 12.2
I-110, MS (Back Bay) -- see http://southeastroa­ds.com/i-110_ms.html­
I-264, VA (Elizabeth R) -- see
http://www.roadstot­hefuture.com/I264_VA­_Desc.html or
http://www.aaroadtr­ips.com/hampton_road­s.html
I-278, NY (Bronx R) -- see http://www.nycroads­.com/roads/bruckner/­
I-280, NJ (Passaic R) -- see http://www.nycroads­.com/roads/I-280_NJ/­
I-280, OH (Maumee R) -- see http://www.roadfan.­com/toledo.html#prop­
(this is being replaced by a fixed span - information at
http://www.lookupto­ledo.org/)
I-695, MD (Curtis Cr) -- see
http://www.roadstot­hefuture.com/Balt_Ou­ter_Harbor.html

Former drawbridges replaced by fixed spans:
I-75, MI (Saginaw R) -- see
http://www.michigan­highways.org/indepth­/zilwaukee.html
I-95, FL (St. Johns R) -- see
http://www.dot.stat­e.fl.us/structures/b­otm/fullerwarren/ful­lerwarren.htm
I-95, NY (Hutchinson R) -- see
http://www.nycroads­.com/roads/new-engla­nd/
I-395 (originally I-95), DC/VA (Potomac R) -- see
http://www.roadstot­hefuture.com/14th_St­reet_Bridge.html (bridge is
still a drawbridge but has been rendered inoperable)
Apr 30, 2005

6.3.8


Q: Why are there Interstate highways in Hawaii? Are there plans for
Interstates in Alaska or Puerto Rico? Are there any freeways in Alaska
or Puerto Rico?

A: The Hxx Interstates were approved by AASHTO when Hawaii became a
state in 1959 to allow Hawaii to have Interstates (see
http://www.fhwa.dot­.gov/infrastructure/­hawaii.htm and
http://www.hawaiihi­ghways.com/FAQs-page­4.htm#why-Interstate­s ). Even
though Alaska and Hawaii do not connect directly to other states, their
highways fall into the same system as those in the other 48 states, so
while "Interstate" can't be literal, the name is there for consistency.
Alaska and Puerto Rico officially have Axx and PRxx routes,
respectively, but these are unsigned and, in Alaska's case at least,
generally not up to Interstate standards. In 1959, when Alaska became a
state, they asked for funding for fully standard Interstates on the
current corridors plus others, including one to Nome. This was
rejected. In 1981, FHWA added current routes A1-A4 to the Interstate
system as 2 lane rural arterials. The only Alaska Interstate routes
that have been upgraded to freeway are AK 1 (A1) east of downtown
Anchorage to just short of the AK 3 (Interstate A4) junction in Palmer,
and a few miles of AK 1 (Interstate A3) south of downtown Anchorage.
Puerto Rico has many rural and urban freeways (autopistas); most of the
rural freeways are tolled. The AK/HI/PR Interstates do not have an "I-"
preceding them in their abbreviations.
Here is a list of the Ax routes:

A1 follows AK 2 from the Canadian border to Tok Junction and then AK 1
to Anchorage.
A2 follows AK 2 from Tok Junction (AK 1) to Fairbanks.
A3 follows AK 1 from Anchorage to Soldotna.
A4 follows AK 3 from Palmer (AK 1) to Fairbanks.

Aug 17, 2004

6.3.9

Q: What's up with I-585 in Spartanburg, SC?

A: When the I-85 bypass around Spartanburg was built, old I-85 became
BUSINESS I-85. I-585 originally ended at I-85 like it should, but since
new I-85 was built it has not touched I-85.
Another oddity on I-585 is the fact that it is signed for several
blocks past the freeway end in downtown Spartanburg.
In other words, I-585 doesn't extend far enough to I-85 and extends too
far on the other end. See http://www.kurumi.c­om/roads/3di/i585.ht­ml and
http://www.intersta­te-guide.com/i-585_s­c.html . May 28, 2003

6.3.10

Q: Why is the Chicago Skyway no longer I-90?

A: Actually, according to FHWA, it still is. In late 1999, Chicago
added a TO banner to all the I-90 reassurance markers on the
city-maintained Skyway. Apparently the city was looking at old records
and realized it was never technically approved as an interstate (see
http://groups-beta.­google.com/group/mis­c.transport.road/msg­/2044938ffca6c8b4
, message ID n9jig-2008991217310­001@chi-pm4-1a-40.th­eramp.net ).
However, in 2005, FHWA rebutted by saying that I-90 is and always has
been on the Skyway, at least since the I-90 and I-94 designations have
been as they have since 1964 (see
http://www.tollroad­snews.com/cgi-bin/a.­cgi/XeXDlOhBEdmcEIJ6­1nsxIA ,
6/28/05).
Another strange fact about the Skyway is that it was built as a 10 mile
toll bridge. Illinois law at the time prohibited non-bridge toll roads,
so Chicago had to get it approved as a toll bridge over the Calumet
River.
In early March 2004 a plan to privatize the Skyway was proposed; this
plan was put into action in mid-October 2004. ("For Sale: Chicago
Skyway", Chicago Sun-Times, March 2, 2004; "Overseas investors to lease
Skyway from city", Chicago Tribune, October 15, 2004)
The Skyway has a McDonald's restaurant in the median by the toll plaza.
Related: http://www.n9jig.co­m/tollways.html Jun 30, 2005

6.3.11

Q: Why does I-180 in IL exist?

A: I-180 serves the town of Hennepin, population 707 (2000 census). It
was built to serve LTV steel, a major defense contractor. In the future
it may be extended south to Peoria, but it currently has almost no
traffic. See http://www.kurumi.c­om/roads/3di/i180.ht­ml#180il ,
http://www.n9jig.co­m/gallery/expw.html , and
http://www.intersta­te-guide.com/i-180_i­l.html . May 28, 2003

6.3.12

Q: What happened to I-265 in Nashville?

A: In late 2000, I-65 was rerouted along the former I-265, which
existed between I-24 and I-40 northwest of downtown, to relieve traffic
on the former I-40/65 multiplex (now I-40 between I-65 and I-24). See
http://www.kurumi.c­om/roads/3di/ix65.ht­ml#265tn and
http://www.intersta­te-guide.com/i-265_t­n.html . May 28, 2003

6.3.13

Q: Are Kentucky's parkways built to Interstate standards?

A: No, according to Carl Dixon, Branch Manager, Division of Planning,
Kentucky Transportation Cabinet. Each of Kentucky's parkways would
require work to reach the standards defined for Interstates. Work that
would be required depends on the parkway; however, the work would
"include more lanes (e.g., the Daniel Boone Parkway), wider median
widths, wider shoulders, reduced grades, smoother curves, improved
interchanges, and possibly several other design details". The Parkways,
however, do allow trucks. The "Parkway" designation stems from the fact
that that's what Kentucky called its toll highways (not all of these
are tolled anymore). I-66 is planned to run along the Cumberland
Parkway and possibly the Boone, Natcher, and Western Kentucky Parkways,
and I-69 is planned to run along the Purchase Parkway and possibly the
Pennyrile and Western Kentucky Parkways (see
http://www.kentucky­roads.com/i-66/ and
http://www.kentucky­roads.com/i-69/ ). Jan 28, 2002

6.3.14

Q: Why do I-17's exit numbers start so high?

A: Until the mid-1980s Arizona used a special system for its mileage --
any route which did not enter Arizona from another state used the
mileage of the route where its southern or western end was for its
point of origin rather than zero (e.g.: If Route 2's southern end was
at Route 1 and Route 1's mileage at the Route 1/Route 2 intersection is
Mile 57, then Route 2's lowest-numbered milemarker would be Mile 57).
I-17 is a special case: Its exit numbers are actually those of the
former longer routing of AZ 69, which branched from US 89 at Mile 201,
since I-17 and AZ 69 were paired early on. AZ 69 has been truncated
since I-17's exits were numbered (see
http://www.arizonar­oads.com/arizona/az6­9.htm ). I-17's exit numbers are
not related to those of I-19 (see 10.3). Feb 20, 2002

6.3.15

Q: What's with the I-465 spur northwest of Indianapolis? What is it
designated?

A: I-865, the east-west I-465 spur which connects I-65 to I-465
northwest of Indianapolis, exists partly because the I-65/I-465
interchange farther south lacks ramps between the north and northwest
(it also has no ramps between the south and southeast). It was formerly
signed as I-465 East eastbound and I-65 North westbound (the I-65/I-465
spur interchange also lacks connections, between the southeast and
east) and was simply considered another part of I-465. It was
renumbered to I-865 in April 2002 and signage was changed beginning in
May 2002. Why it is now called I-865 is thoroughly explained in an
Indiana DOT press release (see
http://www.in.gov/s­erv/presscal?PF=dot&­Clist=6&Elist=52862 ). The spur
also carries US 52, which, while not signposted along most of I-465
(see 3.9.1), is in fact signed along the length of the spur. The
milemarkers on this spur used to start at 900 before it was renumbered.
See also http://www.kurumi.c­om/roads/3di/ix65.ht­ml#465in . Jun 11, 2002

6.3.16

Q: Has there been a proposal to extend eastern I-76 eastward?

A: Not officially. Many laypeople have proposed this extension, which
entails the freeway portion of NJ 42 plus most or all of the Atlantic
City Expressway, but this has not been considered officially due to a
combination of sub-Interstate features, potential confusion, and
disinterest (see
http://groups-beta.­google.com/group/mis­c.transport.road/bro­wse_frm/thread/4a67d­49058462018
). Oct 16, 2003

6.3.17

Q: What's with I-22?

A: I-22 has been signed into law as a designation running along
Appalachian Corridor X (US-78) in TN, MS, and AL. See
http://www.intersta­te-guide.com/i-022.h­tml and
http://www.aaroads.­com/high-priority/co­rr10.html . Jul 19, 2005

6.3.18

Q: What's with I-41?

A: I-41 is designated along US-41 in TEA-LU (see Question 4.3 ). The
condition of I-41 and US-41 existing together in WI (and in fact on the
same highway) has not yet been addressed (see the Section 6 intro for
why this would be noteworthy). For more information see
http://www.intersta­te-guide.com/i-041.h­tml . Jul 19, 2005

6.3.19

Q: What's with the proposed Interstates in the southern US?

A: There are two Interstates being considered in the Southeast, I-3 and
I-14. These would be named after the 3rd Infantry Division of Fort
Stewart in GA and the 14th Amendment to the U.S. Constitution
respectively. For routing information and the history of the proposals,
see http://www.intersta­te-guide.com/i-003.h­tml and
http://www.intersta­te-guide.com/i-014.h­tml .

An eastern I-30 has been proposed for part of US-74 in NC by a NCDOT
employee (see
http://groups-beta.­google.com/group/mis­c.transport.road/bro­wse_frm/thread/85743­af85c2b8a07
, 7/15/05) Jul 19, 2005

6.4

Q: Why do people want I-69 extended?

A: The I-69 extension was proposed by businessmen in the early 1990s to
stimulate international trade between Canada, Mexico and the United
States. It would run from Port Huron, Michigan to Brownsville, Texas.
It currently runs from Port Huron to Indianapolis. In Indiana, it was
decided that I-69 will run along a new alignment from Indianapolis to
Evansville (it will probably multiplex with I-465 around Indianapolis)
rather than along I-70, a new southeast bypass of Terre Haute, and an
upgraded US 41. More information is at
http://www.aaroads.­com/high-priority/co­rr18.html ,
http://www.i69info.­com/ , and
http://dmoz.org/Rec­reation/Roads_and_Hi­ghways/Interstate_69­/ . Jul 9,
2003

6.5

Q: What's this I hear about a new Interstate marker?

A: This is a hoax. Basically the rumor was that AASHTO plans to
implement a new shield design by 2007 or earlier. It was a circle in a
square, considered ugly by most.

6.6

Q: Is one mile of each five in the Interstate system required to be
able to act as an emergency landing strip for aircraft?

A: No. See http://www.tfhrc.go­v/pubrds/mayjun00/on­emileinfive.htm
(official) and http://www.snopes.c­om/autos/law/airstri­p.asp . It was
considered briefly ( http://www.fhwa.dot­.gov/infrastructure/­turner.htm
) but never adopted officially. There are unusually-built overpasses
(truss structure) on a straight section of I-75 near the former
Kincheloe Air Force Base (now Chippewa County International Airport) in
the Upper Peninsula of Michigan, leading to speculation that the
Michigan State Highway Department did build I-75 here to accomodate
aircraft. This is purely speculation, however, with no conclusive proof
Add comment
Marc Fannin 26 August 2005 00:53:20 [ permanent link ]
 Here are Sections 5 and 6.

The FAQ in its entirety is at
http://www.roadfan.­com/mtrfaq.ÂÂÂÂÂhtml­
(c. 275KB)

___________________­____________________­____________________­_____________
Marc Fannin|musxf579@ken­t.edu or @hotmail.com| http://www.roadfan.­com/

-------------------­--

5 Websites

Links to road websites are available at
http://dmoz.org/Rec­reation/Roads_and_Hi­ghways/ (alternate URL:
http://roadlinks.cj­b.net/ ),
http://www.aboutvia­.com/ (alternate URL:
http://www.ugcs.cal­tech.edu/~jlin/links­/ ),
http://www.aaroads.­com/kick-off/highway­.html , and
http://www.cahighwa­ys.org/othlinks.html­ .
(All of these are listed at
http://dmoz.org/Rec­reation/Roads_and_Hi­ghways/Directories/ .)

See also the Wikipedia "Road" entry and related subarticles at
http://en.wikipedia­.org/wiki/Roads .

A list of roadgeeks by location is at
http://www.roadfan.­com/roadfan.html .

Apr 3, 2005


-------------------­--------------------­--------------------­--------------------­-

6 The Interstate Highway System

The Interstate Highway System (or, more formally, the Dwight D.
Eisenhower National System of Interstate and Defense Highways) is a
system of divided controlled access highways present in every state as
well as DC and PR. It has more than 45,000 miles to its credit. A
complete list is found at http://www.ihoz.com­/interstates.html (1 and 2
digit) and http://www.kurumi.c­om/roads/3di/ (3 digit), as well as at
http://www.intersta­te-guide.com/ . Information on planned Interstates
and Interstate extensions can be found at
http://www.aaroads.­com/high-priority/ and
http://www.intersta­te-guide.com/future.­html . FHWA's overview of the
system is at http://www.fhwa.dot­.gov/programadmin/in­terstate.html and a
route log is at http://www.fhwa.dot­.gov/reports/routefi­nder/ . See
Question 6.1 for Interstate history. The U.S. Code of Federal
Regulations lists in Title 23, Appendix A to Subpart A of Part 470, the
"Guidance Criteria for Evaluating Requests for Interstate System
Designations Under [Title] 23 [of the] U.S. [Code, now-repealed
Section] 139 (a) and (b)" (for text, see the portion directly after
Section 470.115 in the respective file at
http://www.access.g­po.gov/nara/cfr/wais­idx_04/23cfr470_04.h­tml ).
AASHTO's Interstate policy is at
http://www.traffics­ign.us/inpolicy.html­ . This policy states among
other items that Interstates and U.S. Highways with the same number
should not exist in the same state, although US-24 and I-24 both exist
in IL, and US-80 and I-80 briefly existed in CA until the former was
truncated outside the state (both instances presumedly overlooked due
to the distance between), and three proposed Interstate extensions and
one new Interstate are planned to exist in states with the
corresponding U.S. route (41 in WI, 49 in AR, 69 in TX, 74 in NC - on
current signage for the latter's pairing with US 74, "FUTURE" replaces
"INTERSTATE" on the I-74 shields - see elsewhere in Section 6 for more
details on each of these).
Even though these routes are known as being federally-marked routes, it
is actually the states that maintain them in most cases, and other
non-federal-level agencies in the rest. The Interstates have received
federal funding of various percentages of the whole throughout the
history of the system, however (see
http://www.cahighwa­ys.org/itypes.html ). Interstates are automatically
included in the National Highway System (see Question 7.7 ).
There are single-state Interstates (see Question 6.12) - the name
"Interstate" refers to the system as a whole and not to any individual
numbered route.
A ranking subject to interpretation of 2-digit Interstates by
importance is located at http://www.kurumi.c­om/roads/rank2di.htm­l .
For business route information see 3.2. Jul 19, 2005

6.1 Interstate History

http://www.fhwa.dot­.gov/infrastructure/­history.htm includes many
historical articles, and http://www.intersta­te50th.org/ has been set up
by AASHTO and includes much historical information. See also Section
17.

Jul 19, 2005
6.1.1

Q: How did the Interstate Highway System come to be?

A: In 1944, Congress authorized construction of an interstate
expressway system connecting major cities and industrial centers. No
money was involved in the bill. The project never took off until the
awarding of the first contract for I-70 in Missouri, in 1956. North
Dakota was the first state to complete its Interstates. More
information is available at
http://www.tfhrc.go­v/pubrds/summer96/p9­6su10.htm and
http://eisenhower.a­rchives.gov/dl/Inter­stateHighways/Inters­tateHighwaysdocument­s.html
. Jul 10, 2003

6.1.2

Q: What was the first stretch of Interstate to open?

A: The first stretch of Interstate opened under the 1944 Congress act
was I-70 in Kansas, which opened in 1957. More information is at
http://www.tfhrc.go­v/pubrds/summer96/p9­6su18.htm 2000-08-17 15:29:33

6.1.3

Q: What were the original plans for Interstates?

A: The Interstate System's original plans are detailed in a publication
called General location of national system of interstate highways,
including all additional routes at urban areas designated in September,
1955, commonly known as the "Yellow Book". Go to
http://www.roadfan.­com/intreg.html#yell­owbk for much more information
including maps. Feb 25, 2002

6.2 Interstate Numbering

There's a very strict plan for numbering Interstate routes. The one and
two-digit routes are the mainlines, with the even numbered routes going
east-west, and the odd routes going north-south. The even routes'
numbers increase as you go north, with the odd Interstate roads
increasing to the east. The major routes end in 0 or 5. As for
three-digit interstates, those that both start and end at a 2-digit
route get an even first digit, while those not connected to the
Interstate system at their end or ends have an odd first digit.
Exceptions to this occur usually when a state has depleted its
respective choices for 3-digit Interstates. If a 3-digit Interstate has
another 3-digit Interstate branching from it (a "grandchild"), then the
numbering for the second-generation highway is the same as for the
first-generation one. In the field are I-105 CA, I-235 KS, I-444 OK,
I-370 MD, I-175/375 FL, I-278/478/678/878 NJ/NY, I-579 PA,
I-280/380/980 CA, I-190 MA, I-590/990 NY, I-495 NY, I-695 DC, and I-795
MD (each intersects with another 3di with a common "root" but not with
its 2di parent). I-195 NJ also used to be one but it now intersects
I-95 directly. For more on numbering see the FHWA site at
http://www.fhwa.dot­.gov/programadmin/in­terstate.html#Inters­tate_Numbering
. Apr 14, 2004

6.2.1 Letter Suffixes

6.2.1.1

Q: What happened to letter extensions on Interstate highways?

A: AASHTO eliminated them in 1980 and told state DOTs to think of other
numbers. Two still remain on I-35. I-15E in California stayed until
1983 (see 6.2.1.3). Jan 18, 2002

6.2.1.2

Q: Why does I-35 split in Dallas and Minneapolis?

A: As stated in the previous question, some Interstates once carried
letter suffixes. All but three were changed in 1980, and one of those
(I-15E in CA) was gone by 1983. The remaining two are the I-35 splits
in Dallas and Minneapolis, which remain because there was no consensus
on what the new numbers would be. The smaller cities, St. Paul and Fort
Worth, did not want their Interstate highways "demoted" to 3di's. Jul
9, 2003

6.2.1.3

Q: What are/were all the suffixed interstates?

A:

Actually existed

I-5W (CA) -- I-505, I-80, I-580, I-205 (see
http://www.cahighwa­ys.org/001-008.html#­005 for details)
I-15E (CA) -- I-215 (see http://www.cahighwa­ys.org/009-016.html#­015 ,
section 2, for details)
I-15W (ID) -- western I-86
I-24W (MO/TN) -- I-155 and US 412
I-35W/I-35E still exists in TX and MN (see 6.2.1.2)
I-35W (KS) -- I-135
I-59B (AL) -- I-459 (Note: "59B" was chosen through a system of
placeholder numbers using "A", "B", etc., as opposed to "B" meaning
"bypass")
I-70N/I-70S (MD) -- I-70/I-270
I-70S (PA) -- I-70 between I-79 and I-76
I-75E (FL) -- I-75 between I-275 termini
I-80N (OR/ID/UT) -- western I-84
I-80N (IA) -- I-680 east of I-29
I-80N (OH) -- I-80/90, I-90, I-490, I-480, and OH 14 between US 250
near Norwalk and I-76 near Ravenna
I-80S (CO/NE) -- western I-76
I-80S (OH/PA/NJ) at first used today's I-76 in OH and PA and I-276 in
PA; later it was rerouted on today's I-76 and I-676 through
Philadelphia and Camden rather than around; and later it was truncated
at today's I-376 when I-76 was created along today's I-376 and the PA
Turnpike
(See http://www.roadfan.­com/ohiomaps.html ,
http://www.pahighwa­ys.com/interstates/p­di.html#I80S , and
http://www.fhwa.dot­.gov/infrastructure/­i76.htm for details on the
OH/PA/NJ I-80N/I-80 and I-80/I-80S)
I-81E (PA) -- I-380
I-180N (ID) -- I-184 in Boise; all other spurs of suffixed 2dis were
non-suffixed


Planned but never signed

The sources for these are the 1957 and 1958 maps on
http://www.roadfan.­com/5758int.html -- see 6.1.3 for more details

I-5E (CA) -- I-5 between I-5W termini (see above)
I-80N (PA/NJ) -- I-78
I-80S (PA) -- I-76 east of Harrisburg
I-81S (PA) -- I-81E (see above)
I-82N (ID) -- I-15W (see above)
I-82S (ID/UT) -- I-80N between I-15W (see above) and I-15
I-90N (NY) -- I-190
I-94N (MI) -- I-196 (now I-96 west of Grand Rapids)
I-95E (RI/MA) -- I-195 (pre-Interstate plans called it US 6)

Dec 4, 2004

6.2.2

Q: Why the heck does I-99 have such a weird number?

A: This has been one of the most contentious questions or topics in the
newsgroup. Unlike other interstate highways, which have their numbers
assigned by AASHTO, I-99's number was assigned in a piece of
appropriations legislation sponsored by former Rep. Bud Shuster
(R-Pa.), through whose district the highway ran.

Many of the regulars on m.t.r take issue with this highway designation
because:

1) Its number was written into law, as described above;

2) Its number is out of place--a highway designated as I-99 should run
right along the Atlantic coast; and

3) From its length (under 70 miles), location (in an area where all the
available 2di designations are already being used), route (basically, a
spur from I-76 to the Altoona/State College area, at least until it
connects to I-80), and the fact that it doesn't come close to any
interstate other than I-76, an odd 3di designation (such as I-576)
would be more appropriate.

As a side note, for now I-99 also has the distinction of being the only
2 digit interstate that does not have a direct interchange with any
other interstate.

More information is available at
http://www.pahighwa­ys.com/interstates/I­99.html . Oct 3, 2004

6.2.3

Q: What is I-238?

A: Interstate 238 is a 2-mile freeway on the east side of San Francisco
Bay, California. It is not numbered according to the regular Interstate
numbering conventions; rather, it was an extension of CA 238. There is
no I-38. More information is at http://www.gbcnet.c­om/roads/I-238/ .
May 28, 2002

6.2.4

Q: Why are there two Interstates 76, 84, 86 and 88?

A: All duplicates but 86 arose around the time when most letter
suffixes on Interstates were removed, though not all replaced a
suffixed Interstate designation. Eastern I-86 (see 6.3.6) was recently
added because there were no other choices that would fit. At one time,
an eastern I-86 existed from Hartford, CT to I-90 in MA; this is now
part of I-84 (see http://www.kurumi.c­om/roads/ct/i86.html­ ). There were
also two I-39s, but I-39 is now signed along I-90 between the two
sections (see http://www.intersta­te-guide.com/i-039.h­tml ). There are
technically two I-74s, but these are planned to be connected, unlike
the other duplicates (see Question 6.3.4 ). May 6, 2005

6.2.5

Q: Which 3di spurs go both directions from a parent?

A: I-305 CA (hidden), I-516 GA, I-526 SC, I-540 AR (small overlap with
I-40), I-170 MO (crosses I-70, ends at I-270), I-580 CA (small overlap
with I-80), I-185 SC (crosses I-85, ends at I-385), I-385 SC, I-390 NY
(crosses I-90, ends at I-490), I-394 MN (crosses I-94, ends at I-494),
I-595 FL; future: I-710 CA, I-355 IL, I-195 NJ; former: I-181 TN (part
south of I-81 was replaced by I-26) Jul 19, 2005

6.3 Oddities

6.3.1

Q: What happens to I-95 in NJ?

A: The short explaination is the "NIMBY factor". Residents of the
Princeton and New Brunswick, NJ, areas managed to kill a section of
I-95 through their towns in the early 1980s; the NJ Turnpike also
opposed it as it would provide an alternate to the toll road. There has
been a gap ever since. On the NJ Turnpike, the I-95 signs disappear.
There is a plan to build an interchange connecting the existing I-95
with the PA Turnpike northeast of Philadelphia, where they currently
cross but do not have an interchange. The new routing would follow the
PA Turnpike connector from the NJ Turnpike across the Delaware River to
the new interchange, where it would resume its old route. This
interchange should be complete around 2008. More information is
available at http://www.njfreewa­ys.com/Interstate_95­_Gap.html ,
http://www.nycroads­.com/roads/I-95_NJ/ , and
http://www.paturnpi­ke.com/i95/ . This will complete the gap between New
York City and Philadelphia, but will not provide easy access to I-287
from Philadelphia for bypassing New York City as original I-95 would
have.
Some propose rerouting I-95 on the NJ Turnpike all the way to the
Delaware Memorial Bridge and I-295; this is how most through traffic
goes anyway. Many people have a problem with this because it would
bypass Philadelphia. Sep 30, 2004

6.3.1.1

Q: Are I-95's exit numbers between I-80 and NY an extension of I-80's?

A: No. Those numbers are based on the original mileage of I-95 in NJ
including the unbuilt portion mentioned above in 6.3.1 (see the
relevant section of http://www.nycroads­.com/roads/I-95_NJ/ ). Sep 30,
2004

6.3.2

Q: Why do some Interstates, such as I-180 in WY, have traffic lights or
at-grade intersections?

A: Usually Interstates are not allowed to have any cross traffic. In
fact at-grade intersections have kept the new I-86 in New York from
extending further east. But in these cases, AASHTO granted variances
because there was no other reasonable way to build them.
Wyoming I-180 is the only Interstate with no freeway portions. There
are three stoplights. Why was it commissioned in the first place? The
state of Wyoming wanted an Interstate serving downtown Cheyenne. It was
to be freeway, but that idea was rejected. More information is at
http://www.rockymou­ntainroads.com/wyomi­ng/i-180.html
I-676 in Philadelphia, PA has some traffic lights between the Vine St
Expressway and the Ben Franklin Bridge. Construction of a freeway
connection would impact several historic landmarks. There is some doubt
among roadgeeks as to whether I-676 actually goes this way; the
official PennDOT maps label the freeway connection to I-95 as 0676 and
put US 30 on the Ben Franklin Bridge. There is an I-676 shield on the
county map, but shields reflect actual signage, not internal
designations (as the 0676 does). NJDOT however takes I-676 over the
bridge officially and in signage. (See
http://www.pahighwa­ys.com/interstates/I­676.html)
I-78 in Jersey City, NJ runs along a one-way pair of surface streets
between the end of the Turnpike Extension and the Holland Tunnel. I-78
ends just across the border in Manhattan, New York City, so it could be
truncated, but hasn't been. NJ 139 also runs along those streets, as if
NJDOT were prepared for truncation. FHWA, NJDOT, and NYSDOT all
officially refer to these last few miles as I-78. (See also 12.2 )
I-70 in Breezewood, PA is the most famous of these. It runs along a
short section of US 30 lined with businesses between the north-south
free portion of I-70 and the Turnpike connection. It would be fairly
easy to construct direct ramps, but the businesses have been successful
in blocking them. Some think the influential congressman Bud Shuster
has helped block the ramps. (See 3.1 above)
I-585 in Spartanburg, SC is signed past the end of the freeway past
several traffic lights. It is unknown why; the road is also US 176.
(See 6.3.9)
I-690 at the NY State Fairgrounds in Syracuse has a pedestrian crossing
that only functions during the NY State Fair. Because this is only in
operation for a small period of time, it is not worth it to build an
overpass.
I-8, I-10 and I-17 in AZ, I-40 in NC, I-10 and I-40 in W. TX, and I-40
in NM have some at-grade intersections for forest, farm, and ranch
access (see http://www.arizonar­oads.com/wrong/). Most of these highways
were built directly over a pre-existing rural two-lane road, so this is
the only access for many of these properties. Interchanges would not be
worth the expense due to the extremely low traffic which these
intersecting roads carry (some in fact are private).
AK Interstates have signals, but that is because those Interstate
designations are "hidden" along state highways which are usually
surface roads with at-grade intersections (see Question 6.3.8 ).

Several other interstates end at traffic lights, but this is perfectly
OK as long as this is not a 3di's only connection to its parent or an
even 3di's only connection to another interstate at one end.
One example of this that is often brought up is I-587 is Kingston, NY;
this connects to the I-87 ramp via a traffic circle. However, a traffic
circle is somewhat up to standards; there is no cross traffic.
In fact there is a case of a 3DI not meeting its parent; the
abovementioned I-585 in Spartanburg, SC ends at Business Loop I-85,
which is the old I-85 (and is a freeway, but not up to full interstate
standards). It continues to I-85 (bypass) as 4 lane US 176, which is
due for upgrades soon. (See 6.3.9)
I-65 in NW IN formerly had a traffic light installed in 1980 at the IN
Toll Road (I-90) connection at the north end (map at
http://terraserver-­usa.com/image.aspx?t­=4&s=11&z=16&x=1186&­y=11510&w=3
); this was considered by INDOT to be mainline I-65 (
http://www.in.gov/d­ot/div/technology/in­terchanges/I65/is262­.pdf - note
that this diagram shows the rail crossing just north of the signalized
intersection as active; it actually was abandoned by the time I-65 was
extended northward to US-12/20) but was not really the same case of a
traffic light on an Interstate as other examples because the section
north of this signal functioned more like a ramp pair, and was probably
considered one by AASHTO. This has been replaced by conventional
grade-separated freeway ramps.
I-291 in Springfield, MA, has an access point at I-90/MA Turnpike
similar to the former I-65/I-90 junction cited above, albeit with a
more simple design (
http://terraserver-­usa.com/image.aspx?T­=4&S=10&Z=18&X=3514&­Y=23353&W=3
).

Several tunnels on the system have signals at their portals, either to
stop unwanted vehicles from entering (too tall, too heavy, too wide,
hazardous material carrier) or for traffic capacity control.

Question 6.3.7 deals with drawbridges on Interstates, which have
traffic lights but no cross traffic.

Railroad crossings:
The Interstate highway specifications do not permit railroad grade
crossings. A few did exist before, but all have either been grade
separated or had the tracks removed. However, a number of crossings do
still exist on some non-Interstate highways with controlled access. In
many of these cases, the crossing is classified as "Exempt" by the
particular state, meaning that vehicles normally required to stop at
railroad crossings, such as vehicles carrying hazardous material and
school buses, can continue through without stopping. Instead, all
trains are required to send a flagman to clear the highway traffic
before it may proceed. These crossings are rarely busy railroad
mainlines, as they tend to be lightly-used or even disused industrial
spurs. Exempt crossings are noted with a tab on the advance RxR warning
sign post and/or on the crossbuck post itself (see
http://mutcd.fhwa.d­ot.gov/HTM/2003r1/pa­rt8/part8b.htm#secti­on8B05 ).

Former crossings on Interstates:
I-65 north end in IN (see above). Abandoned, then interchange
reconstructed.
I-87 Adirondack Northway, NY, near the Mohawk River. This line was
apparently already up for abandonment with the now-defunct Interstate
Commerce Commission when the Interstate was being built, so it did not
pay to build an overpass that would be useless in a few years.
I-94 near Ypsilanti, MI. Now abandoned. This same line used to cross US
23 at-grade as well.
I-94 near Albion, MI. Now abandoned.
I-395 in N. VA (Shirley Highway) near Glebe Rd. Crossing dismantled
when the Washington & Old Dominion RR folded. Note that this was while
it had its pre-Interstate designation (VA 350).

Existing crossings on non-Interstate controlled-access highways [* -
Exempt]: US-1, Edison, NJ (Jersey Freeway - see 3.14); US-4 near
Rutland, VT; US-12/14/18/151, Madison, WI; US-30/250, Wooster, OH*;
US-60, Springfield, MO; US-63, Columbia, MO; US 151, Beaver Dam, WI;
US-151, Waupun, WI; US-301, Rocky Mount, NC; US-322 between Harrisburg
and Hershey, PA*; NY-49 near Rome*; OH-7, north of Martins Ferry;
Atlantic City-Brigantine Connector, NJ*

Other former grade crossings on major divided highways: US-1, Danvers,
MA; US-3, Billerica, MA; US-4, Portsmouth, NH; US-6, Denver, CO;
US-12/14/18/151, Madison, WI (2 others in addition to the current one);
US-23 south of Dundee, MI (and others); US-64, Tulsa, OK (2); US-131,
Kalamazoo, MI; MA-2, Concord; NY-17 (Quickway)/future I-86 near
Middletown, NY

Note: The above question refers to Interstate intersections with roads
which carry general traffic and not roadways such as maintenance roads
(intersections between these and freeways are common throughout the
U.S.). Jun 16, 2005

6.3.3

Q: Where was the Embarcadero Freeway and why was it torn down?

A: The Embarcadero Freeway, I-480, would have connected the Bay Bridge
to the Golden Gate Bridge in San Francisco, carrying mostly local
traffic. The first section north from I-80 was built. Most San
Francisco residents hated it because it blocked the view of the
waterfront from the other side. After a 1989 earthquake almost made it
collapse, it was permanently closed and torn down. The same thing
happened to the northern half and most of the upper deck of the Central
Skyway (US 101). Across the Bay in Oakland, part of the Cypress Freeway
(I-880) actually collapsed, killing some motorists. This double decker
freeway was torn down and rebuilt on a new alignment; the old alignment
is now a wide boulevard with a park in the middle.
More information is at http://www.cahighwa­ys.org/371-480.html#­480 and
http://www.kurumi.c­om/roads/3di/i480.ht­ml#480ca . Apr 9, 2004

6.3.4

Q: Why are these I-73 and I-74 signs popping up in North Carolina?

A: Interstate 73 and the 74 extension are specified in the ISTEA
legislation. I-73 will go from Sault Ste. Marie, Michigan to Myrtle
Beach, South Carolina, while the 74 extension will head east from its
present Cincinnati, Ohio terminus to Portsmouth, Ohio and be mostly
multiplexed with 73 south of there. A North Carolina portion south of
Greensboro was already freeway, so they installed signs there. Some
states are reluctant to build the new highway, specifically Ohio. More
information is at http://www.aaroads.­com/high-priority/co­rr05.html
2000-08-11 19:10:26

6.3.5

Q: Why are there freeway loops in Phoenix?

A: The loop freeways are not Interstates because they are funded by a
1/2 cent sales tax paid by county residents, not by Federal money. If
these freeways had waited for inclusion in the Interstate system, they
may have been delayed for years, or never been built at all. More
information is at http://www.arizonar­oads.com/urban/ . Jan 15, 2002

6.3.6 What is the new I-86?

The eastern I-86, the newest 2di, runs from just outside Erie, PA, to
East Corning, NY, along state route 17, the Southern Tier Expressway.
The move was designed to spurt economic development in the Elmira and
Binghamton areas. This part was designated in late 1999; it is planned
to extend east to I-87 at Harriman once the at-grade intersections are
eliminated. More information is at
http://www.aaroads.­com/high-priority/co­rr36.html Apr 8, 2002

6.3.6.1

Q: Does it really dip into Pennsylvania?

A: Yes, it does. Exit 60 (US 220) is entirely in Pennsylvania, and the
dip is complete with "STATE BORDER" signs. However, New York maintains
it. Maps: http://www.empirest­ateroads.com/maps/wa­verly.jpg ,
http://terraserver-­usa.com/image.aspx?S­=12&T=2&X=466&Y=5813­&Z=18&W=2 By
the way, this is not part of I-86 yet. Sep 2, 2003

6.3.7

Q: Where are all the drawbridges on the Interstate system?

A: These all had to get variances from FHWA to be approved into the
interstate system.
I-5, OR/WA (Columbia R) -- see
http://www.bizave.c­om/cgi-bin/photoalbu­m.cgi?photoalbum=pdx­bridges&slidetag=Int­erstate
and http://www.columbia­n.com/reflections/br­idge.cfm (this is planned to
be replaced - information at http://www.columbia­rivercrossing.org/ )
I-64, VA (Elizabeth R) -- see
http://www.roadstot­hefuture.com/I64_VA_­Desc.html or
http://www.aaroadtr­ips.com/hampton_road­s.html
I-95/495, VA/DC/MD (Potomac R); see
http://www.roadstot­hefuture.com/Woodrow­_Wilson_Bridge.html (this is
being replaced by a higher drawbridge - information at
http://www.wilsonbr­idge.com/ ) See also 12.2
I-110, MS (Back Bay) -- see http://southeastroa­ds.com/i-110_ms.html­
I-264, VA (Elizabeth R) -- see
http://www.roadstot­hefuture.com/I264_VA­_Desc.html or
http://www.aaroadtr­ips.com/hampton_road­s.html
I-278, NY (Bronx R) -- see http://www.nycroads­.com/roads/bruckner/­
I-280, NJ (Passaic R) -- see http://www.nycroads­.com/roads/I-280_NJ/­
I-280, OH (Maumee R) -- see http://www.roadfan.­com/toledo.html#prop­
(this is being replaced by a fixed span - information at
http://www.lookupto­ledo.org/)
I-695, MD (Curtis Cr) -- see
http://www.roadstot­hefuture.com/Balt_Ou­ter_Harbor.html

Former drawbridges replaced by fixed spans:
I-75, MI (Saginaw R) -- see
http://www.michigan­highways.org/indepth­/zilwaukee.html
I-95, FL (St. Johns R) -- see
http://www.dot.stat­e.fl.us/structures/b­otm/fullerwarren/ful­lerwarren.htm
I-95, NY (Hutchinson R) -- see
http://www.nycroads­.com/roads/new-engla­nd/
I-395 (originally I-95), DC/VA (Potomac R) -- see
http://www.roadstot­hefuture.com/14th_St­reet_Bridge.html (bridge is
still a drawbridge but has been rendered inoperable)
Apr 30, 2005

6.3.8


Q: Why are there Interstate highways in Hawaii? Are there plans for
Interstates in Alaska or Puerto Rico? Are there any freeways in Alaska
or Puerto Rico?

A: The Hxx Interstates were approved by AASHTO when Hawaii became a
state in 1959 to allow Hawaii to have Interstates (see
http://www.fhwa.dot­.gov/infrastructure/­hawaii.htm and
http://www.hawaiihi­ghways.com/FAQs-page­4.htm#why-Interstate­s ). Even
though Alaska and Hawaii do not connect directly to other states, their
highways fall into the same system as those in the other 48 states, so
while "Interstate" can't be literal, the name is there for consistency.
Alaska and Puerto Rico officially have Axx and PRxx routes,
respectively, but these are unsigned and, in Alaska's case at least,
generally not up to Interstate standards. In 1959, when Alaska became a
state, they asked for funding for fully standard Interstates on the
current corridors plus others, including one to Nome. This was
rejected. In 1981, FHWA added current routes A1-A4 to the Interstate
system as 2 lane rural arterials. The only Alaska Interstate routes
that have been upgraded to freeway are AK 1 (A1) east of downtown
Anchorage to just short of the AK 3 (Interstate A4) junction in Palmer,
and a few miles of AK 1 (Interstate A3) south of downtown Anchorage.
Puerto Rico has many rural and urban freeways (autopistas); most of the
rural freeways are tolled. The AK/HI/PR Interstates do not have an "I-"
preceding them in their abbreviations.
Here is a list of the Ax routes:

A1 follows AK 2 from the Canadian border to Tok Junction and then AK 1
to Anchorage.
A2 follows AK 2 from Tok Junction (AK 1) to Fairbanks.
A3 follows AK 1 from Anchorage to Soldotna.
A4 follows AK 3 from Palmer (AK 1) to Fairbanks.

Aug 17, 2004

6.3.9

Q: What's up with I-585 in Spartanburg, SC?

A: When the I-85 bypass around Spartanburg was built, old I-85 became
BUSINESS I-85. I-585 originally ended at I-85 like it should, but since
new I-85 was built it has not touched I-85.
Another oddity on I-585 is the fact that it is signed for several
blocks past the freeway end in downtown Spartanburg.
In other words, I-585 doesn't extend far enough to I-85 and extends too
far on the other end. See http://www.kurumi.c­om/roads/3di/i585.ht­ml and
http://www.intersta­te-guide.com/i-585_s­c.html . May 28, 2003

6.3.10

Q: Why is the Chicago Skyway no longer I-90?

A: Actually, according to FHWA, it still is. In late 1999, Chicago
added a TO banner to all the I-90 reassurance markers on the
city-maintained Skyway. Apparently the city was looking at old records
and realized it was never technically approved as an interstate (see
http://groups-beta.­google.com/group/mis­c.transport.road/msg­/2044938ffca6c8b4
, message ID n9jig-2008991217310­001@chi-pm4-1a-40.th­eramp.net ).
However, in 2005, FHWA rebutted by saying that I-90 is and always has
been on the Skyway, at least since the I-90 and I-94 designations have
been as they have since 1964 (see
http://www.tollroad­snews.com/cgi-bin/a.­cgi/XeXDlOhBEdmcEIJ6­1nsxIA ,
6/28/05).
Another strange fact about the Skyway is that it was built as a 10 mile
toll bridge. Illinois law at the time prohibited non-bridge toll roads,
so Chicago had to get it approved as a toll bridge over the Calumet
River.
In early March 2004 a plan to privatize the Skyway was proposed; this
plan was put into action in mid-October 2004. ("For Sale: Chicago
Skyway", Chicago Sun-Times, March 2, 2004; "Overseas investors to lease
Skyway from city", Chicago Tribune, October 15, 2004)
The Skyway has a McDonald's restaurant in the median by the toll plaza.
Related: http://www.n9jig.co­m/tollways.html Jun 30, 2005

6.3.11

Q: Why does I-180 in IL exist?

A: I-180 serves the town of Hennepin, population 707 (2000 census). It
was built to serve LTV steel, a major defense contractor. In the future
it may be extended south to Peoria, but it currently has almost no
traffic. See http://www.kurumi.c­om/roads/3di/i180.ht­ml#180il ,
http://www.n9jig.co­m/gallery/expw.html , and
http://www.intersta­te-guide.com/i-180_i­l.html . May 28, 2003

6.3.12

Q: What happened to I-265 in Nashville?

A: In late 2000, I-65 was rerouted along the former I-265, which
existed between I-24 and I-40 northwest of downtown, to relieve traffic
on the former I-40/65 multiplex (now I-40 between I-65 and I-24). See
http://www.kurumi.c­om/roads/3di/ix65.ht­ml#265tn and
http://www.intersta­te-guide.com/i-265_t­n.html . May 28, 2003

6.3.13

Q: Are Kentucky's parkways built to Interstate standards?

A: No, according to Carl Dixon, Branch Manager, Division of Planning,
Kentucky Transportation Cabinet. Each of Kentucky's parkways would
require work to reach the standards defined for Interstates. Work that
would be required depends on the parkway; however, the work would
"include more lanes (e.g., the Daniel Boone Parkway), wider median
widths, wider shoulders, reduced grades, smoother curves, improved
interchanges, and possibly several other design details". The Parkways,
however, do allow trucks. The "Parkway" designation stems from the fact
that that's what Kentucky called its toll highways (not all of these
are tolled anymore). I-66 is planned to run along the Cumberland
Parkway and possibly the Boone, Natcher, and Western Kentucky Parkways,
and I-69 is planned to run along the Purchase Parkway and possibly the
Pennyrile and Western Kentucky Parkways (see
http://www.kentucky­roads.com/i-66/ and
http://www.kentucky­roads.com/i-69/ ). Jan 28, 2002

6.3.14

Q: Why do I-17's exit numbers start so high?

A: Until the mid-1980s Arizona used a special system for its mileage --
any route which did not enter Arizona from another state used the
mileage of the route where its southern or western end was for its
point of origin rather than zero (e.g.: If Route 2's southern end was
at Route 1 and Route 1's mileage at the Route 1/Route 2 intersection is
Mile 57, then Route 2's lowest-numbered milemarker would be Mile 57).
I-17 is a special case: Its exit numbers are actually those of the
former longer routing of AZ 69, which branched from US 89 at Mile 201,
since I-17 and AZ 69 were paired early on. AZ 69 has been truncated
since I-17's exits were numbered (see
http://www.arizonar­oads.com/arizona/az6­9.htm ). I-17's exit numbers are
not related to those of I-19 (see 10.3). Feb 20, 2002

6.3.15

Q: What's with the I-465 spur northwest of Indianapolis? What is it
designated?

A: I-865, the east-west I-465 spur which connects I-65 to I-465
northwest of Indianapolis, exists partly because the I-65/I-465
interchange farther south lacks ramps between the north and northwest
(it also has no ramps between the south and southeast). It was formerly
signed as I-465 East eastbound and I-65 North westbound (the I-65/I-465
spur interchange also lacks connections, between the southeast and
east) and was simply considered another part of I-465. It was
renumbered to I-865 in April 2002 and signage was changed beginning in
May 2002. Why it is now called I-865 is thoroughly explained in an
Indiana DOT press release (see
http://www.in.gov/s­erv/presscal?PF=dot&­Clist=6&Elist=52862 ). The spur
also carries US 52, which, while not signposted along most of I-465
(see 3.9.1), is in fact signed along the length of the spur. The
milemarkers on this spur used to start at 900 before it was renumbered.
See also http://www.kurumi.c­om/roads/3di/ix65.ht­ml#465in . Jun 11, 2002

6.3.16

Q: Has there been a proposal to extend eastern I-76 eastward?

A: Not officially. Many laypeople have proposed this extension, which
entails the freeway portion of NJ 42 plus most or all of the Atlantic
City Expressway, but this has not been considered officially due to a
combination of sub-Interstate features, potential confusion, and
disinterest (see
http://groups-beta.­google.com/group/mis­c.transport.road/bro­wse_frm/thread/4a67d­49058462018
). Oct 16, 2003

6.3.17

Q: What's with I-22?

A: I-22 has been signed into law as a designation running along
Appalachian Corridor X (US-78) in TN, MS, and AL. See
http://www.intersta­te-guide.com/i-022.h­tml and
http://www.aaroads.­com/high-priority/co­rr10.html . Jul 19, 2005

6.3.18

Q: What's with I-41?

A: I-41 is designated along US-41 in TEA-LU (see Question 4.3 ). The
condition of I-41 and US-41 existing together in WI (and in fact on the
same highway) has not yet been addressed (see the Section 6 intro for
why this would be noteworthy). For more information see
http://www.intersta­te-guide.com/i-041.h­tml . Jul 19, 2005

6.3.19

Q: What's with the proposed Interstates in the southern US?

A: There are two Interstates being considered in the Southeast, I-3 and
I-14. These would be named after the 3rd Infantry Division of Fort
Stewart in GA and the 14th Amendment to the U.S. Constitution
respectively. For routing information and the history of the proposals,
see http://www.intersta­te-guide.com/i-003.h­tml and
http://www.intersta­te-guide.com/i-014.h­tml .

An eastern I-30 has been proposed for part of US-74 in NC by a NCDOT
employee (see
http://groups-beta.­google.com/group/mis­c.transport.road/bro­wse_frm/thread/85743­af85c2b8a07
, 7/15/05) Jul 19, 2005

6.4

Q: Why do people want I-69 extended?

A: The I-69 extension was proposed by businessmen in the early 1990s to
stimulate international trade between Canada, Mexico and the United
States. It would run from Port Huron, Michigan to Brownsville, Texas.
It currently runs from Port Huron to Indianapolis. In Indiana, it was
decided that I-69 will run along a new alignment from Indianapolis to
Evansville (it will probably multiplex with I-465 around Indianapolis)
rather than along I-70, a new southeast bypass of Terre Haute, and an
upgraded US 41. More information is at
http://www.aaroads.­com/high-priority/co­rr18.html ,
http://www.i69info.­com/ , and
http://dmoz.org/Rec­reation/Roads_and_Hi­ghways/Interstate_69­/ . Jul 9,
2003

6.5

Q: What's this I hear about a new Interstate marker?

A: This is a hoax. Basically the rumor was that AASHTO plans to
implement a new shield design by 2007 or earlier. It was a circle in a
square, considered ugly by most.

6.6

Q: Is one mile of each five in the Interstate system required to be
able to act as an emergency landing strip for aircraft?

A: No. See http://www.tfhrc.go­v/pubrds/mayjun00/on­emileinfive.htm
(official) and http://www.snopes.c­om/autos/law/airstri­p.asp . It was
considered briefly ( http://www.fhwa.dot­.gov/infrastructure/­turner.htm
) but never adopted officially. There are unusually-built overpasses
(truss structure) on a straight section of I-75 near the former
Kincheloe Air Force Base (now Chippewa County International Airport) in
the Upper Peninsula of Michigan, leading to speculation that the
Michigan State Highway Department did build I-75 here to accomodate
aircraft. This is purely speculation, however, with no conclusive proof
so far.

Conversely, there was a Cold-War bunker built under I-5 in Seattle, at
the Ravenna Boulevard overpass, by the state of Washington in the ear
Add comment
Sam Inman 26 August 2005 04:05:17 [ permanent link ]
 Marc Fannin wrote:> Here are Sections 5 and 6.>
The FAQ in its entirety is at> http://www.roadfan.­com/mtrfaq.ÂÂÂÂÂhtml­> (c. 275KB)>
___________________­____________________­____________________­_____________> Marc Fannin|musxf579@ken­t.edu or @hotmail.com| http://www.roadfan.­com/>
-------------------­-->
5 Websites>
Links to road websites are available at> http://dmoz.org/Rec­reation/Roads_and_Hi­ghways/ (alternate URL:> http://roadlinks.cj­b.net/ ),> http://www.aboutvia­.com/ (alternate URL:> http://www.ugcs.cal­tech.edu/~jlin/links­/ ),> http://www.aaroads.­com/kick-off/highway­.html , and> http://www.cahighwa­ys.org/othlinks.html­ .> (All of these are listed at> http://dmoz.org/Rec­reation/Roads_and_Hi­ghways/Directories/ .)>
See also the Wikipedia "Road" entry and related subarticles at> http://en.wikipedia­.org/wiki/Roads .>
A list of roadgeeks by location is at> http://www.roadfan.­com/roadfan.html .>
Apr 3, 2005>
-------------------­--------------------­--------------------­--------------------­->
6 The Interstate Highway System>
The Interstate Highway System (or, more formally, the Dwight D.> Eisenhower National System of Interstate and Defense Highways) is a> system of divided controlled access highways present in every state as> well as DC and PR. It has more than 45,000 miles to its credit. A> complete list is found at http://www.ihoz.com­/interstates.html (1 and 2> digit) and http://www.kurumi.c­om/roads/3di/ (3 digit), as well as at> http://www.intersta­te-guide.com/ . Information on planned Interstates> and Interstate extensions can be found at> http://www.aaroads.­com/high-priority/ and> http://www.intersta­te-guide.com/future.­html . FHWA's overview of the> system is at http://www.fhwa.dot­.gov/programadmin/in­terstate.html and a> route log is at http://www.fhwa.dot­.gov/reports/routefi­nder/ . See> Question 6.1 for Interstate history. The U.S. Code of Federal> Regulations lists in Title 23, Appendix A to Subpart A of Part 470, the> "Guidance Criteria for Evaluating Requests for Interstate System> Designations Under [Title] 23 [of the] U.S. [Code, now-repealed> Section] 139 (a) and (b)" (for text, see the portion directly after> Section 470.115 in the respective file at> http://www.access.g­po.gov/nara/cfr/wais­idx_04/23cfr470_04.h­tml ).> AASHTO's Interstate policy is at> http://www.traffics­ign.us/inpolicy.html­ . This policy states among> other items that Interstates and U.S. Highways with the same number> should not exist in the same state, although US-24 and I-24 both exist> in IL, and US-80 and I-80 briefly existed in CA until the former was> truncated outside the state (both instances presumedly overlooked due> to the distance between), and three proposed Interstate extensions and> one new Interstate are planned to exist in states with the> corresponding U.S. route (41 in WI, 49 in AR, 69 in TX, 74 in NC - on> current signage for the latter's pairing with US 74, "FUTURE" replaces> "INTERSTATE" on the I-74 shields - see elsewhere in Section 6 for more> details on each of these).> Even though these routes are known as being federally-marked routes, it> is actually the states that maintain them in most cases, and other> non-federal-level agencies in the rest. The Interstates have received> federal funding of various percentages of the whole throughout the> history of the system, however (see> http://www.cahighwa­ys.org/itypes.html ). Interstates are automatically> included in the National Highway System (see Question 7.7 ).> There are single-state Interstates (see Question 6.12) - the name> "Interstate" refers to the system as a whole and not to any individual> numbered route.> A ranking subject to interpretation of 2-digit Interstates by> importance is located at http://www.kurumi.c­om/roads/rank2di.htm­l .> For business route information see 3.2. Jul 19, 2005>
6.1 Interstate History>
http://www.fhwa.dot­.gov/infrastructure/­history.htm includes many> historical articles, and http://www.intersta­te50th.org/ has been set up> by AASHTO and includes much historical information. See also Section> 17.>
Jul 19, 2005> 6.1.1>
Q: How did the Interstate Highway System come to be?>
A: In 1944, Congress authorized construction of an interstate> expressway system connecting major cities and industrial centers. No> money was involved in the bill. The project never took off until the> awarding of the first contract for I-70 in Missouri, in 1956. North> Dakota was the first state to complete its Interstates. More> information is available at> http://www.tfhrc.go­v/pubrds/summer96/p9­6su10.htm and> http://eisenhower.a­rchives.gov/dl/Inter­stateHighways/Inters­tateHighwaysdocument­s.html> . Jul 10, 2003>
6.1.2>
Q: What was the first stretch of Interstate to open?>
A: The first stretch of Interstate opened under the 1944 Congress act> was I-70 in Kansas, which opened in 1957. More information is at> http://www.tfhrc.go­v/pubrds/summer96/p9­6su18.htm 2000-08-17 15:29:33>
6.1.3>
Q: What were the original plans for Interstates?>
A: The Interstate System's original plans are detailed in a publication> called General location of national system of interstate highways,> including all additional routes at urban areas designated in September,> 1955, commonly known as the "Yellow Book". Go to> http://www.roadfan.­com/intreg.html#yell­owbk for much more information> including maps. Feb 25, 2002>
6.2 Interstate Numbering>
There's a very strict plan for numbering Interstate routes. The one and> two-digit routes are the mainlines, with the even numbered routes going> east-west, and the odd routes going north-south. The even routes'> numbers increase as you go north, with the odd Interstate roads> increasing to the east. The major routes end in 0 or 5. As for> three-digit interstates, those that both start and end at a 2-digit> route get an even first digit, while those not connected to the> Interstate system at their end or ends have an odd first digit.> Exceptions to this occur usually when a state has depleted its> respective choices for 3-digit Interstates. If a 3-digit Interstate has> another 3-digit Interstate branching from it (a "grandchild"), then the> numbering for the second-generation highway is the same as for the> first-generation one. In the field are I-105 CA, I-235 KS, I-444 OK,> I-370 MD, I-175/375 FL, I-278/478/678/878 NJ/NY, I-579 PA,> I-280/380/980 CA, I-190 MA, I-590/990 NY, I-495 NY, I-695 DC, and I-795> MD (each intersects with another 3di with a common "root" but not with> its 2di parent). I-195 NJ also used to be one but it now intersects> I-95 directly. For more on numbering see the FHWA site at> http://www.fhwa.dot­.gov/programadmin/in­terstate.html#Inters­tate_Numbering> . Apr 14, 2004>
6.2.1 Letter Suffixes>
6.2.1.1>
Q: What happened to letter extensions on Interstate highways?>
A: AASHTO eliminated them in 1980 and told state DOTs to think of other> numbers. Two still remain on I-35. I-15E in California stayed until> 1983 (see 6.2.1.3). Jan 18, 2002>
6.2.1.2>
Q: Why does I-35 split in Dallas and Minneapolis?>
A: As stated in the previous question, some Interstates once carried> letter suffixes. All but three were changed in 1980, and one of those> (I-15E in CA) was gone by 1983. The remaining two are the I-35 splits> in Dallas and Minneapolis, which remain because there was no consensus> on what the new numbers would be. The smaller cities, St. Paul and Fort> Worth, did not want their Interstate highways "demoted" to 3di's. Jul> 9, 2003>
6.2.1.3>
Q: What are/were all the suffixed interstates?>
A:>
Actually existed>
I-5W (CA) -- I-505, I-80, I-580, I-205 (see> http://www.cahighwa­ys.org/001-008.html#­005 for details)> I-15E (CA) -- I-215 (see http://www.cahighwa­ys.org/009-016.html#­015 ,> section 2, for details)> I-15W (ID) -- western I-86> I-24W (MO/TN) -- I-155 and US 412> I-35W/I-35E still exists in TX and MN (see 6.2.1.2)> I-35W (KS) -- I-135> I-59B (AL) -- I-459 (Note: "59B" was chosen through a system of> placeholder numbers using "A", "B", etc., as opposed to "B" meaning> "bypass")> I-70N/I-70S (MD) -- I-70/I-270> I-70S (PA) -- I-70 between I-79 and I-76> I-75E (FL) -- I-75 between I-275 termini> I-80N (OR/ID/UT) -- western I-84> I-80N (IA) -- I-680 east of I-29> I-80N (OH) -- I-80/90, I-90, I-490, I-480, and OH 14 between US 250> near Norwalk and I-76 near Ravenna> I-80S (CO/NE) -- western I-76> I-80S (OH/PA/NJ) at first used today's I-76 in OH and PA and I-276 in> PA; later it was rerouted on today's I-76 and I-676 through> Philadelphia and Camden rather than around; and later it was truncated> at today's I-376 when I-76 was created along today's I-376 and the PA> Turnpike> (See http://www.roadfan.­com/ohiomaps.html ,> http://www.pahighwa­ys.com/interstates/p­di.html#I80S , and> http://www.fhwa.dot­.gov/infrastructure/­i76.htm for details on the> OH/PA/NJ I-80N/I-80 and I-80/I-80S)> I-81E (PA) -- I-380> I-180N (ID) -- I-184 in Boise; all other spurs of suffixed 2dis were> non-suffixed>
Planned but never signed>
The sources for these are the 1957 and 1958 maps on> http://www.roadfan.­com/5758int.html -- see 6.1.3 for more details>
I-5E (CA) -- I-5 between I-5W termini (see above)> I-80N (PA/NJ) -- I-78> I-80S (PA) -- I-76 east of Harrisburg> I-81S (PA) -- I-81E (see above)> I-82N (ID) -- I-15W (see above)> I-82S (ID/UT) -- I-80N between I-15W (see above) and I-15> I-90N (NY) -- I-190> I-94N (MI) -- I-196 (now I-96 west of Grand Rapids)> I-95E (RI/MA) -- I-195 (pre-Interstate plans called it US 6)>
Dec 4, 2004>
6.2.2>
Q: Why the heck does I-99 have such a weird number?>
A: This has been one of the most contentious questions or topics in the> newsgroup. Unlike other interstate highways, which have their numbers> assigned by AASHTO, I-99's number was assigned in a piece of> appropriations legislation sponsored by former Rep. Bud Shuster> (R-Pa.), through whose district the highway ran.>
Many of the regulars on m.t.r take issue with this highway designation> because:>
1) Its number was written into law, as described above;>
2) Its number is out of place--a highway designated as I-99 should run> right along the Atlantic coast; and>
3) From its length (under 70 miles), location (in an area where all the> available 2di designations are already being used), route (basically, a> spur from I-76 to the Altoona/State College area, at least until it> connects to I-80), and the fact that it doesn't come close to any> interstate other than I-76, an odd 3di designation (such as I-576)> would be more appropriate.>
As a side note, for now I-99 also has the distinction of being the only> 2 digit interstate that does not have a direct interchange with any> other interstate.>
More information is available at> http://www.pahighwa­ys.com/interstates/I­99.html . Oct 3, 2004>
6.2.3>
Q: What is I-238?>
A: Interstate 238 is a 2-mile freeway on the east side of San Francisco> Bay, California. It is not numbered according to the regular Interstate> numbering conventions; rather, it was an extension of CA 238. There is> no I-38. More information is at http://www.gbcnet.c­om/roads/I-238/ .> May 28, 2002>
6.2.4>
Q: Why are there two Interstates 76, 84, 86 and 88?>
A: All duplicates but 86 arose around the time when most letter> suffixes on Interstates were removed, though not all replaced a> suffixed Interstate designation. Eastern I-86 (see 6.3.6) was recently> added because there were no other choices that would fit. At one time,> an eastern I-86 existed from Hartford, CT to I-90 in MA; this is now> part of I-84 (see http://www.kurumi.c­om/roads/ct/i86.html­ ). There were> also two I-39s, but I-39 is now signed along I-90 between the two> sections (see http://www.intersta­te-guide.com/i-039.h­tml ). There are> technically two I-74s, but these are planned to be connected, unlike> the other duplicates (see Question 6.3.4 ). May 6, 2005>
6.2.5>
Q: Which 3di spurs go both directions from a parent?>
A: I-305 CA (hidden), I-516 GA, I-526 SC, I-540 AR (small overlap with> I-40), I-170 MO (crosses I-70, ends at I-270), I-580 CA (small overlap> with I-80), I-185 SC (crosses I-85, ends at I-385), I-385 SC, I-390 NY> (crosses I-90, ends at I-490), I-394 MN (crosses I-94, ends at I-494),> I-595 FL; future: I-710 CA, I-355 IL, I-195 NJ; former: I-181 TN (part> south of I-81 was replaced by I-26) Jul 19, 2005>
6.3 Oddities>
6.3.1>
Q: What happens to I-95 in NJ?>
A: The short explaination is the "NIMBY factor". Residents of the> Princeton and New Brunswick, NJ, areas managed to kill a section of> I-95 through their towns in the early 1980s; the NJ Turnpike also> opposed it as it would provide an alternate to the toll road. There has> been a gap ever since. On the NJ Turnpike, the I-95 signs disappear.> There is a plan to build an interchange connecting the existing I-95> with the PA Turnpike northeast of Philadelphia, where they currently> cross but do not have an interchange. The new routing would follow the> PA Turnpike connector from the NJ Turnpike across the Delaware River to> the new interchange, where it would resume its old route. This> interchange should be complete around 2008. More information is> available at http://www.njfreewa­ys.com/Interstate_95­_Gap.html ,> http://www.nycroads­.com/roads/I-95_NJ/ , and> http://www.paturnpi­ke.com/i95/ . This will complete the gap between New> York City and Philadelphia, but will not provide easy access to I-287> from Philadelphia for bypassing New York City as original I-95 would> have.> Some propose rerouting I-95 on the NJ Turnpike all the way to the> Delaware Memorial Bridge and I-295; this is how most through traffic> goes anyway. Many people have a problem with this because it would> bypass Philadelphia. Sep 30, 2004>
6.3.1.1>
Q: Are I-95's exit numbers between I-80 and NY an extension of I-80's?>
A: No. Those numbers are based on the original mileage of I-95 in NJ> including the unbuilt portion mentioned above in 6.3.1 (see the> relevant section of http://www.nycroads­.com/roads/I-95_NJ/ ). Sep 30,> 2004>
6.3.2>
Q: Why do some Interstates, such as I-180 in WY, have traffic lights or> at-grade intersections?>
A: Usually Interstates are not allowed to have any cross traffic. In> fact at-grade intersections have kept the new I-86 in New York from> extending further east. But in these cases, AASHTO granted variances> because there was no other reasonable way to build them.> Wyoming I-180 is the only Interstate with no freeway portions. There> are three stoplights. Why was it commissioned in the first place? The> state of Wyoming wanted an Interstate serving downtown Cheyenne. It was> to be freeway, but that idea was rejected. More information is at> http://www.rockymou­ntainroads.com/wyomi­ng/i-180.html> I-676 in Philadelphia, PA has some traffic lights between the Vine St> Expressway and the Ben Franklin Bridge. Construction of a freeway> connection would impact several historic landmarks. There is some doubt> among roadgeeks as to whether I-676 actually goes this way; the> official PennDOT maps label the freeway connection to I-95 as 0676 and> put US 30 on the Ben Franklin Bridge. There is an I-676 shield on the> county map, but shields reflect actual signage, not internal> designations (as the 0676 does). NJDOT however takes I-676 over the> bridge officially and in signage. (See> http://www.pahighwa­ys.com/interstates/I­676.html)> I-78 in Jersey City, NJ runs along a one-way pair of surface streets> between the end of the Turnpike Extension and the Holland Tunnel. I-78> ends just across the border in Manhattan, New York City, so it could be> truncated, but hasn't been. NJ 139 also runs along those streets, as if> NJDOT were prepared for truncation. FHWA, NJDOT, and NYSDOT all> officially refer to these last few miles as I-78. (See also 12.2 )> I-70 in Breezewood, PA is the most famous of these. It runs along a> short section of US 30 lined with businesses between the north-south> free portion of I-70 and the Turnpike connection. It would be fairly> easy to construct direct ramps, but the businesses have been successful> in blocking them. Some think the influential congressman Bud Shuster> has helped block the ramps. (See 3.1 above)> I-585 in Spartanburg, SC is signed past the end of the freeway past> several traffic lights. It is unknown why; the road is also US 176.> (See 6.3.9)> I-690 at the NY State Fairgrounds in Syracuse has a pedestrian crossing> that only functions during the NY State Fair. Because this is only in> operation for a small period of time, it is not worth it to build an> overpass.> I-8, I-10 and I-17 in AZ, I-40 in NC, I-10 and I-40 in W. TX, and I-40> in NM have some at-grade intersections for forest, farm, and ranch> access (see http://www.arizonar­oads.com/wrong/). Most of these highways> were built directly over a pre-existing rural two-lane road, so this is> the only access for many of these properties. Interchanges would not be> worth the expense due to the extremely low traffic which these> intersecting roads carry (some in fact are private).> AK Interstates have signals, but that is because those Interstate> designations are "hidden" along state highways which are usually> surface roads with at-grade intersections (see Question 6.3.8 ).>
Several other interstates end at traffic lights, but this is perfectly> OK as long as this is not a 3di's only connection to its parent or an> even 3di's only connection to another interstate at one end.> One example of this that is often brought up is I-587 is Kingston, NY;> this connects to the I-87 ramp via a traffic circle. However, a traffic> circle is somewhat up to standards; there is no cross traffic.> In fact there is a case of a 3DI not meeting its parent; the> abovementioned I-585 in Spartanburg, SC ends at Business Loop I-85,> which is the old I-85 (and is a freeway, but not up to full interstate> standards). It continues to I-85 (bypass) as 4 lane US 176, which is> due for upgrades soon. (See 6.3.9)> I-65 in NW IN formerly had a traffic light installed in 1980 at the IN> Toll Road (I-90) connection at the north end (map at> http://terraserver-­usa.com/image.aspx?t­=4&s=11&z=16&x=1186&­y=11510&w=3> ); this was considered by INDOT to be mainline I-65 (> http://www.in.gov/d­ot/div/technology/in­terchanges/I65/is262­.pdf - note> that this diagram shows the rail crossing just north of the signalized> intersection as active; it actually was abandoned by the time I-65 was> extended northward to US-12/20) but was not really the same case of a> traffic light on an Interstate as other examples because the section> north of this signal functioned more like a ramp pair, and was probably> considered one by AASHTO. This has been replaced by conventional> grade-separated freeway ramps.> I-291 in Springfield, MA, has an access point at I-90/MA Turnpike> similar to the former I-65/I-90 junction cited above, albeit with a> more simple design (>