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For the most part, the Interstate Highway System in the United States is a connected system, with most roads completed. However, some Interstates still have gaps.

Contents 1 True gaps 2 Disputed gaps 3 Freeway gaps 3.1 At-grade intersections and traffic lights 3.2 Undivided freeways 3.3 Drawbridges 4 Connection gaps 5 Duplicated Route Numbers 6 Other gaps 7 Sources 8 References

[edit] True gaps

True gaps are where two sections of road are intended to be part of the same Interstate, but the two sections are not physically connected, or are only connected by non-Interstates, or are connected but the connection is not signed as part of the highway.

• I-74 currently has three sections, one heading west from Cincinnati, Ohio, one from the Virginia/North Carolina state line along I-77 south and east to a point southeast of Mount Airy, North Carolina, and one concurrent with the only section of I-73, from Emery, North Carolina to Ulah, North Carolina. Other sections up to freeway standards are signed with I-74 shields that have FUTURE instead of INTERSTATE. Future I-73 shields are also placed along some of these sections, but only one section of I-73 is signed with normal Interstate shields.
• I-95. Probably the best-known and significant of the Interstate gaps, I-95 is discontinuous in Lawrence Township, New Jersey (near Trenton). Coming north from Philadelphia, Pennsylvania, I-95 loops around the north side of Trenton and ends at U.S. Route 1, where it becomes I-295, which heads back south. The other section of I-95 begins on the Pennsylvania Turnpike at the Pennsylvania/New Jersey state line, and heads north along the New Jersey Turnpike. Originally I-95 was planned to have left the alignment north of Trenton and headed northeast to I-287 and run east along I-287 to Exit 10 on the Turnpike, but this "Somerset Freeway" was never built. Extensions over the years have taken I-95 several miles further north to the US 1 interchange northeast of Trenton, and south along the New Jersey Turnpike to the Pennsylvania state line. Eventually an interchange will be built connecting the southern alignment with the Pennsylvania Turnpike, and I-95 will be rerouted via it, with the part north of that interchange becoming an extension of I-195 (it was originally considered as an extension of I-295).

[edit] Disputed gaps

• I-90. There are some people that believe that there is presently a gap in I-90 at the Chicago Skyway, but there is controversy and confusion surrounding this issue. Historically the skyway was commonly considered to be, and was signed as, part of I-90 (originally I-94). However, around 1999 the City of Chicago, Illinois determined it may never have applied for approval to sign it as an Interstate. (It also is not designed to Interstate standards.) The city resigned the skyway, and it is now mostly posted with "TO I-90" signs, with a few older signs remaining. Because of this development, it has been widely circulated, especially among road buffs, that there is now a gap in I-90. However, the Illinois Department of Transportation has always and continues to report the skyway as part of the Interstate system, and the Federal Highway Administration still considers it as such. A FHWA legal memo says "There is no doubt about it. The Chicago Skyway is officially part of I-90 that (has) always been included in the Dwight D. Eisenhower National System of Interstate and Defense Highways."<ref>http://www.fhwa.dot.gov/programadmin/toll_Rds.html</ref><ref>http://tollroadsnews.info/artman/publish/article_969.shtml</ref>
• I-265. The Indiana portion of I-265 does not yet connect with the Kentucky portion of I-265. Each of the two segments, circling the outskirts and suburbs of Louisville, Kentucky, ends before crossing the Ohio River. Plans for constructing a bridge to connect the two segments have been finalized, though the project is far from complete.<ref>http://www.kyinbridges.com/</ref> It is possible this is not a gap, as both parts are in two different states and could be entirely 'separate' freeways.

[edit] Freeway gaps

Freeway gaps, where the Interstate is signed as a continuous route, but part or all of it is not up to freeway standards. This includes drawbridges where traffic on the Interstate can be stopped for vessels.

[edit] At-grade intersections and traffic lights

• Several Interstates in the southwest U.S. have at-grade intersections (including median breaks) with minor farm access roads. This is usually due to the lack of an old highway, and the need to provide access to property that was accessed via the road prior to upgrade to Interstate, and the high cost to construct an interchange for the small amount of traffic that using such a connection. For instance, I-40 in both the western Texas Panhandle and western North Carolina has several driveways intersecting directly with the road.
• I-70 uses part of US 30 along a surface road in Breezewood, Pennsylvania to get between the freeway heading south to Hancock, Maryland and the ramp to the Pennsylvania Turnpike. This is probably the best-known instance of traffic lights on an interstate. There used to be a sign of a policeman pointing at drivers leaving the Pennsylvania Turnpike to enter US 30, saying, "You! Slow Down!" Local businesses have lobbied to keep the gap to avoid loss of business.<ref>http://maps.google.com/maps?q=Breezewood+PA&ll=39.999224,-78.235917 Map</ref> <ref>http://terraserver.microsoft.com/image.aspx?T=1&S=10&Z=17&X=3680&Y=22156&W=2&qs=%7cBreezewood%7cPA Aerial photo</ref> Photos of Eastbound I-70 with traffic lights: <ref>http://www.okroads.com/031603/i70pabreezewood.jpg</ref> <ref>http://www.okroads.com/031603/i70pabreezewood_2.jpg</ref> from <ref>http://www.okroads.com/delaware/i70pa.html</ref>
• I-78 travels along a one-way pair of surface streets, 12th Street and 14th Street, in Jersey City, New Jersey, between the end of the New Jersey Turnpike Newark Bay Extension and the Holland Tunnel which leads into New York, New York. Along with the aforementioned I-70, this is the only other primary interstate with traffic lights (which exist on both the ends of the tunnel). <ref>http://maps.google.com/maps?q=Jersey+City+NJ&ll=40.731088,-74.041382&spn=0.003317,0.008615&t=h Map and Aerial photo</ref> Photos of traffic lights in I-78: <ref>http://www.interstate-guide.com/images051/i-078_et_03.jpg Eastbound I-78 in Jersey City</ref>, <ref>http://www.interstate-guide.com/images051/i-078_et_02.jpg Westbound I-78 in New York City</ref> from <ref>http://www.interstate-guide.com/i-078.html</ref>
• I-180 in Cheyenne, Wyoming has no parts built to freeway standards; in fact the interchange with I-80 is even a simple diamond interchange with two traffic lights on I-180, however it is expressway-quality with a few grade-separations. <ref>http://maps.google.com/maps?q=Cheyenne+WY&ll=41.124657,-104.80751&spn=0.01319,0.034461 Map</ref> <ref>http://maps.yahoo.com/beta/index.php#mvt=h&maxp=search&q1=Cheyenne+WY&trf=0&lon=-104.808605&lat=41.123542&mag=3 Aerial photo</ref>
• I-585 is cosigned with US 176, in which I-585 shields are present in beyond the point where it ceases to be a freeway, having passed through traffic lights. There also exists a sign that marks the road there as "I-585 Business Spur" and hence it is unclear whether that surface section of US 176 also belongs to I-585.
• I-676 has a surface street section at the west end of the Ben Franklin Bridge in Philadelphia, Pennsylvania because of historically significant areas. Signage and the Federal Highway Administration consider I-676 to use the surface streets, but the Pennsylvania Department of Transportation may consider I-676 to stay on the freeway to end at I-95, with the surface streets and the bridge being only US 30, and the part in New Jersey being a different I-676.<ref>http://maps.google.com/maps?q=Philadelphia&ll=39.955757,-75.150797&spn=0.003355,0.008615&t=h Aerial photo</ref>
• I-690 in Syracuse, New York has a traffic light for one or two weeks each year, for buses to carry Great New York State Fair attendees from parking areas across the road to the fair.

[edit] Undivided freeways

This section addresses two-lane freeways and other undivided freeway sections of the Interstate, excepting instances of continuing routes using one-lane ramps.

• I-81 is undivided as it crosses over the Thousand Islands Bridge near Alexandria Bay, New York.
• I-93 used to have a true gap through Franconia Notch State Park in northern New Hampshire. The road filling the gap, a section of US 3, is built to freeway standards but has only one lane in each direction to avoid adversely impacting the Old Man of the Mountain; such a road is known as a two-lane freeway. Around 2002, the road, which had been signed as US 3 TO I-93, was resigned as a concurrency of I-93 and US 3. Exit numbers, which had been discontinuous with I-93, were renumbered to fit the rest of I-93. Even though the Old Man has since fallen, widening I-93 is still a problem due to the pristine nature of the area.

[edit] Drawbridges

• I-5 crosses the Columbia River from Portland, Oregon to Vancouver, Washington on the Interstate Bridge, a drawbridge. The Washington State Senate Transportation Committee is considering replacing this bridge.
• I-64/Hampton Roads Beltway crosses the South Branch of the Elizabeth River in Chesapeake, Virginia on the High Rise Bridge, a drawbridge. This is the part of I-64 which does not have "east" and "west" posted on it, because of I-64 curving to the opposite compass direction.
• I-95/I-495/Capital Beltway passes over the Potomac River on the new Woodrow Wilson Bridge, a drawbridge, south of Washington, DC. While this bridge will require fewer openings than the old Woodrow Wilson Bridge (which is being demolished), there will be an estimated 65 openings per year.
• I-110 has a drawbridge across the Back Bay of Biloxi in Biloxi, Mississippi.
• I-264 has a drawbridge (Berkley Bridge) over the Elizabeth River in Norfolk, Virginia.
• I-278 has a drawbridge across the Bronx River in New York, New York.
• I-280 has a drawbridge (Stickel Memorial Bridge) over the Passaic River connecting Newark, New Jersey to Harrison, New Jersey.
• I-280 has a drawbridge (Craig Memorial Bridge) over the Maumee River in Toledo, Ohio; a non-drawbridge replacement should be finished in 2007.
• I-395 passes over the Potomac River on the 14th Street Bridge in Washington, DC, which used to be a drawbridge but is now inoperative (adjacent fixed spans constructed in the years leading up to the draw span's decommissioning have a clearance of 18 feet, so permanently shutting the draw span was no particular loss).
• I-695/Baltimore Beltway has a drawbridge over Curtis Creek south of Baltimore, Maryland, a bit to the west of the Francis Scott Key Bridge.

[edit] Connection gaps

Auxiliary Interstates (also known to as 3-digit Interstates) are supposed to connect back to their parent either directly or via a same-parented Interstate (like I-280 in California being connected to I-80 via I-680). Those that don't, have a connection gap:

• I-238 in Alameda County, California, is unique in that there is no parent I-38. I-238 does intersect two spurs of I-80, I-580 and I-880. I-238 was named after the connecting CA-238, because there were eight I-80 spurs in California already at the time, and a CA-180 (California does not like to use the same number twice, even for different designation shields). Since then, I-480 has been demolished and its number is now free. Theoretically, I-238 could become I-480 and become in line with standards.
• I-585 used to connect with I-85 in Spartanburg, South Carolina, but I-85 was moved to a bypass and now I-585 ends at an I-85 Business loop. The signed connection to I-85 is via a surface section of US 176.
• I-210 in California at present does not directly connect to I-10, though it used to (via what is now CA 57) and will again (through what is now CA 30) by 2008 when the last segment of CA 210 is finished and renamed to I-210.
• None of the spurs of I-78 (I-278, I-478, I-678, I-878) connects to its parent. I-78 was planned to extend through New York City and end as two branches, where I-295 and I-695 now end at I-95. I-478 comes the closest, and would have intersected if the Westway project wasn't canceled; I-278, the only I-78 spur to leave New York City, was planned to extend northwest to I-78 at Route 24. Since all the spurs are interconnected, only one of them needs to be eventually connected to its parent route for all of them to conform to standards.
• I-189 was originally supposed to connect with planned I-289, but the project was halted when Burlington was able to transition from an industrial center to a tourism economy.

[edit] Duplicated Route Numbers

In some cases, interstate route numbers are used on two separate, unconnected lengths of roadway, one in the eastern portion of the country and one in the western portion. Unlike true gaps, these gaps are intentional. That is, there was never any intent that the two sections of roadway bearing the same number would be linked together someday.

• I-86

The original designation of I-86 is a 63-mile-long connector route in Idaho and is totally useless. It was originally numbered I-15W but was renumbered in the 1970s<ref>http://www.interstate-guide.com/i-086_west.html</ref>. Essentially, I-86 forms the top leg of a triangle, stretching from its western terminus with I-84 at Heyburn, ID, to its eastern terminus with I-15 at Pocatello, ID. The third point of the triangle is the intersection of I-84 and I-15 at Tremonton, UT

The eastern I-86 was formerly New York SR-17. As SR-17 is brought up to federal standards section by section (portions of SR-17 were compliant freeways, while others were non-compliant highways), the compliant sections are redesignated as I-86<ref>http://www.interstate-guide.com/i-086_east.html</ref>. Portions of SR-17/I-86 have been signed "FUTURE I-86," indicating that they will someday be part of the interstate system.<ref>http://www.fhwa.dot.gov/planning/econdev/i86trip2005.htm</ref>

• I-84

The eastern I-84 runs from Sturbridge, MA, to Scranton, PA.

The western I-84 begins in Echo, UT, and ends in Portland, OR.

• I-76

The eastern I-76 travels from its eastern terminus with I-295 in Camden, NJ, to its western terminus with I-71 in Akron, OH.

The western I-76 is a bypass route allowing traffic on westbound I-80 to travel southwest into Denver, CO without going through Cheyenne, WY. It was originally numbered I-80S.

[edit] Other gaps

Not covered here are a few other cases worth mentioning:

• Gaps in Interstate Highway standards, such as shoulder widths and bridge clearances, since these are too frequent
• Gaps on the Interstates in Alaska and Puerto Rico, since those are not held to the same standards
• Places where Interstates cross but don't connect via a freeway-standard connection (e.g. I-84 and I-87. This will soon be remedied in the future, however).
• Places where Interstates cross but don't connect at all (e.g. I-78 and I-476).
• Places where a three-digit Interstate connects to its parent via another three-digit Interstate of the same parent; the numbering system allows for this (e.g. I-270 and I-370).
• Sometimes, near toll booths (e.g. Mackinac Bridge toll booth), a brief segment of the Interstate will have a median break with a double-yellow line but have at least 4 lanes total.
• Metering lights to regulate the flow of traffic onto bridges and skyways, such as those on westbound I-80 approaching the San Francisco-Oakland Bay Bridge.
• Median breaks for maintenance and/or emergency vehicles to access government driveways. These exist on many highways that are otherwise considered freeways, including Interstates.
• Places where interstates end at a traffic light, such as the west end of I-630 at Shackleford Road in Little Rock, Arkansas. Though technically not gaps, they are similar in many respects, especially where the through route continues through the light like I-630 (as Financial Centre Parkway and then Chenal Parkway).
• Business loops and spurs are not subject to mainline freeway standards.

edit Main Interstate Highways (major in pink)														Image:I-blank.svg
4	5	8	10	12	15	16	17	19	20	22	24	25	26	27	29
30	35	37	39	40	43	44	45	49	55	57	59	64	65	66
66 (W)		68	69	70	71	72	73	74	75	76 (W)		76 (E)		77	78
79	80	81	82	83	84 (W)		84 (E)		85	86 (W)		86 (E)		87
88 (W)		88 (E)		89	90	91	93	94	95	96	97	99	(238)
H-1	H-2	H-3
Unsigned			A-1	A-2	A-3	A-4	PRI-1		PRI-2		PRI-3
Lists		Main - Auxiliary - Suffixed - Business - Proposed - Unsigned Gaps - Intrastate - Interstate standards - Replaced

[edit] Sources

• misc.transport.road FAQ

[edit] References