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 |
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 across the United States.
- 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 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.
- 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, 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 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."[1][2] Incidentally, this stretch of I-90 is north of I-94, contrary to the usual south-to-north numbering order.
- 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.[3]
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. This does not include facilities such as tollbooths or toll plazas, agricultural inspection stations (as found in California), or border stations.
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 use such a connection or build a frontage road parallel to the freeway to the nearest interchange. For instance, I-40 in both the western Texas Panhandle and in Haywood County in western North Carolina has several driveways and small roads intersecting directly with the highway. Such intersections can also be spotted on rural segments of I-5, particularly in southwestern Washington and central California.
- 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 (Map, Aerial photo).
-
- Photos: [1] [2] (from OKRoads.com)
- 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).[4]
-
- Photos: Eastbound in Jersey City, Westbound in New York City (from Interstate Guide)
- 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 (Map, Aerial photo).
- 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, 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 (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-81 at the Thousand Islands Bridge is an undivided two lane road going across the bridge.
- 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 (The Old Man collapsed anyway 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.[5]
Drawbridges
Current
- 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.[6]
- 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.
Former
- I-95 was originally built with a drawbridge over the Hutchinson River in New York City. This bridge was replaced with a high-level fixed span in the late 1990s, and the drawbridge has since been demolished.
- The Fuller Warren Bridge on in I-95 in Jacksonville was originally built with a drawbridge over the St. Johns River. It was replaced with a new span bridge in 2002.
- I-280 (Ohio) used to use a drawbridge (Craig Memorial Bridge) over the Maumee River in Toledo, Ohio; On June 24, 2007, the Veterans' Glass City Skyway officially opened, thus finally closing the gap in this Interstate.
- I-395 passes over the Potomac River on the 14th Street Bridge in Washington, D.C., 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-75 used to have a drawbridge at Zilwalkee; it has been replaced with a higher bridge that does not stop traffic.
Connection gaps
Auxiliary Interstates (also known to as 3-digit Interstates) are supposed 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-210 in California at present does not directly connect to I-10, though it used to (via what is now State Route 57) and will again (through what is now State Route 30) by 2008, when the last segment of State Route 210 is finished and renamed to I-210.
- 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 theoretically free. I-238 could become I-480 and become in-line with standards. However, 238 is also the atomic mass number of the most common isotope of uranium, and so, the number could be taken to honor the nearby Lawrence-Livermore nuclear laboratories.
- 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.
- I-279 in Pittsburgh, Pennsylvania will feature a connection gap when infrastructure work is complete on US-22 and PA Route 60. At this point, I-279 will lose its southern connection with I-79 because the stretch of highway west of and including the Fort Pitt Tunnel will be redesignated I-376.
Other gaps
- 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. Coincidentally, most of these are route numbers in the 80s (eg. I-84, I-86, I-88)
- 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 in New York.). (NOTE: 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).
- 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 or I-89's terminus at I-93's in Bow, New Hampshire.
- 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.
Sources
References
- ^ http://www.fhwa.dot.gov/programadmin/toll_Rds.html
- ^ http://tollroadsnews.info/artman/publish/article_969.shtml
- ^ http://www.kyinbridges.com/
- ^ 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
- ^ http://www.fhwa.dot.gov/infrastructure/intrstat.cfm
- ^ http://www.columbiarivercrossing.org/
| Main Interstate Highways (multiples of 5 in pink) |  |
||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 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 | 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 | Primary | Main - Intrastate - Suffixed - Future - Gaps | |||||||||||||||||
| Auxiliary | Main - Future - Unsigned | ||||||||||||||||||
| Other | Standards - Business - Bypassed | ||||||||||||||||||
![[1]](http://www.okroads.com/031603/i70pabreezewood.jpg){kind=link}
![[2]](http://www.okroads.com/031603/i70pabreezewood_2.jpg){kind=link}
