List of gaps in Interstate Highways

List of gaps in Interstate Highways

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.

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.

*Interstate 69 has two sections: the original alignment runs from Indianapolis, Indiana to Port Huron, Michigan. On October 2, 2006, a segment of I-69 opened in Tunica County, Mississippi and DeSoto County, Mississippi. These segments will eventually be connected as I-69 is extended south to Texas.
*Interstate 74 currently has three sections, one heading west from Cincinnati, Ohio to Iowa, one from the Virginia/North Carolina state line along Interstate 77 south and east to a point southeast of Mount Airy, North Carolina, and one concurrent with the only section of I-73, from Ellerbe, 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.
*Interstate 95. Probably the best-known and notoriously confusing of all 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, heading to southern New Jersey. The other section of I-95 begins on the Pennsylvania Turnpike at the Pennsylvania/New Jersey state line, heads east into New Jersey along a spur of the New Jersey Turnpike, then heads north along the New Jersey Turnpike mainline. Originally I-95 was planned to have left the alignment north of Trenton and headed northeast to Interstate 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 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 to be an extension of I-295.)

Disputed gaps

*I-90 at the Chicago Skyway — 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 re-signed the Skyway, and it is now mostly posted with "TO I-90" signs, with a few older signs remaining. 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." [] []
*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, 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. [ [ Kentucky Indiana Bridges - Home ] ]

Freeway gaps

Freeway gaps occur 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. This does not include facilities such as tollbooths, toll plazas, agricultural inspection stations, or border stations.

At-grade intersections and traffic lights

*Several Interstates in rural areas of the 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 use such a connection or build a frontage road parallel to the freeway to the nearest interchange.
*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 ( [,-78.235917 Map] ). [Manuel Roig-Franzia, "The Town That Stops Traffic: Travelers Encounter Way Station as Way of Life in Breezewood," "Washington Post", 22 November 2001, B1.]
*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 City. Along with the aforementioned I-70, this is the only other primary interstate with traffic lights (which exist on both ends of the tunnel). [,-74.041382&spn=0.003317,0.008615&t=h Map and Aerial photo]
*I-180 in Cheyenne, Wyoming has no parts built to freeway standards; in fact the interchange with I-80 is just a simple diamond interchange with two traffic lights on I-180, however it is expressway-quality with a few grade-separations ( [,-104.80751&spn=0.01319,0.034461 Map] ).
*I-585 in Spartanburg, South Carolina, 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; the Pennsylvania Department of Transportation and the New Jersey Department of Transportation consider I-676 to be continuous across the Ben Franklin Bridge, even though the bridge, built in 1926, is not up to Interstate standards ( [,-75.150797&spn=0.003355,0.008615&t=h Aerial photo] ).
*I-690 in Syracuse, New York, has a traffic light for twelve days each year, for buses to carry Great New York State Fair attendees from parking areas across the road to the fair.

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-93 is a two-lane, divided parkway, or "Super Two", through Franconia Notch in New Hampshire. A four-lane interstate was proposed, but was abandoned due to environmental concerns, in part related to vibrations which could harm the Old Man of the Mountain (which collapsed in 2003). The section was, for many years, signed as US 3 and "To 93" but has since been replaced with I-93 shields. The Federal Highway Act of 1973 exempts this stretch from Interstate standards, and it is considered I-93 by FHWA. [ [ Interstate System Conditions and Performance - Highway History - Infrastructure - FHWA ] ]


*I-5 crosses the Columbia River from Portland, Oregon to Vancouver, Washington on the Interstate Bridge, a drawbridge. There are plans to replace it with a higher one and extend the MAX Light Rail system to Vancouver. [ [ Columbia River Crossing: Home ] ]
*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, D.C. While this bridge requires fewer openings than the old Woodrow Wilson Bridge (which was demolished in the summer of 2006), there will still 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 Bronx, New York.
*I-280 (New Jersey) has a drawbridge (Stickel Memorial Bridge) over the Passaic River connecting Newark, New Jersey to Harrison, New Jersey.
*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.

Connection gaps

Auxiliary Interstates (also known as 3-digit Interstates) are intended to connect to their parent either directly or via a same-parented Interstate (like I-280 in California being connected to I-80 via I-680).
*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 State Route 238, because there were eight I-80 spurs in California already at the time, and a State Route 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 unused.
*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-585 used to connect with I-85 in Spartanburg, South Carolina, but I-85 was moved to a new bypassing route, and now I-585 ends at the I-85 Business loop. The signed connection to I-85 is via a surface section of US 176.

Other gaps

*In four cases — I-76, I-84, I-86 and I-88 — the same primary interstate route numbers is used on two separate, unconnected lengths of roadway, one in the eastern portion of the country and one in the western portion. These gaps are intentional – the two segments of roadway are not planned to be linked together.
*Gaps in Interstate Highway standards, such as shoulder widths and bridge clearances, occur too frequently to list.
*Gaps on the Interstates in Alaska and Puerto Rico, because those highways 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 in New York). There is construction going on to change this by the mid-2010s.
*"Non-Interchanges" where two Interstates cross but don't connect at all (e.g., I-78 and I-476 in Allentown, PA).
*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 non-spur interstates appear to end at a traffic light soon after intersecting with another freeway, such as I-17's terminus at I-40 in Flagstaff, Arizona.
*Places where an Interstate technically ends partway across a nonconforming bridge on an international crossing, such as where I-75 and I-81 cross into Canada.
*Business loops and spurs are not subject to mainline freeway standards.



* [ misc.transport.road FAQ]

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