Interstate 78

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Template:Routeboxint Interstate 78 (abbreviated I-78) is an Interstate Highway in the Northeast United States, running 144 miles (231 km) from Interstate 81 northeast of Harrisburg, Pennsylvania across northern New Jersey to downtown New York City. Its length in New York is only 1/2 mile (1 km) - half of the Holland Tunnel and the plaza immediately beyond. The route once ran east and north through New York City to end at Interstate 95 in The Bronx, but sections of the planned route, including the Lower Manhattan Expressway, were cancelled. The portion that goes through New Jersey is sometimes called the Phillipsburg-Newark Expressway.

lengths
mi km
PA 75.23 121.07
NJ 67.83 109.16
NY 0.50 0.80
143.56 231.04

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Route description

I-78 begins at a directional-T interchange with Interstate 81 in Union Township, Lebanon County, Pennsylvania, about 25 miles (40 km) northeast of Harrisburg. Near the east end of the county, at exit 8, the four-lane divided U.S. Route 22 merges with I-78; the road from here to exit 51, where US 22 splits, was built as a realignment of US 22 in the 1950s; part of the road west of Hamburg, built as a surface road, was rebuilt as a freeway in the early 1960s. The pre-1950s US 22 exists for the most part, though a piece of it at the west end of the concurrency was upgraded on the spot.

At exit 51, in Upper Macungie Township, I-78 leaves the 1950s US 22 freeway for an early-1990s bypass to the south of Allentown, Bethlehem and Easton, crossing the Delaware River into New Jersey on the Interstate 78 Toll Bridge (tolled westbound). South of Allentown, most of the late-1950s Route 309 freeway was incorporated into I-78 (and completely rebuilt); PA 309 now runs concurrent with I-78. Access to Interstate 476, the Northeast Extension of the Pennsylvania Turnpike, is via the US 22 freeway, accessed via PA 309 from the east.

The 1990s alignment ends at exit 3 in New Jersey, where U.S. Route 22 rejoins I-78. Unlike in Pennsylvania, US 22 from the Delaware River east to I-78 is not a freeway; this is one reason the newer bypass was built. I-78 from exit 3 to exit 13 (west of Clinton) was built ca. 1960, with the freeway east of exit 11 built next to the old road (now Route 173). This section runs up and down Musconetcong Mountain with a summit near mile 10; the west slope features an automatic deicing spray. [1] From exit 13 to exit 15, the old road was upgraded on the spot, and Route 173 joins I-78 and US 22 for a three-way concurrency. I-78 and US 22 continue east around the south side of Clinton to exit 16 (Route 31 north) on a ca. 1957 bypass.

From Route 31, I-78 and US 22 continue concurrently to exit 18, running south of Annandale on a ca. 1970 freeway. At exit 18, US 22 splits onto a four-lane surface highway, while I-78 continues roughly parallel. Exit 29, a complicated interchange at Interstate 287, provides access to other areas of northeast New Jersey. The ca. 1970 freeway ends at exit 41, a local exit for Drift Road in Watchung. The section from Drift Road to Route 24 (exit 48) in Springfield Township was delayed because of environmental impacts to the Watchung Reservation. That section, opened in 1985 and 1986, was redesigned to allow construction to proceed. Extra land was added to the Nike Site Road overpass (mile 45.74) and a separate land bridge at mile 46.18 was built to allow for animal migration. These land bridges were later scorned by local communities for the amount of deer (and the resulting damage to flora on private property) that moved into the neighboring towns of Summit, New Providence and Berkeley Heights. The road was also designed to use a narrower right-of-way with no median strip and just a Jersey barrier dividing the highway.

At Route 24, a freeway heading northwest towards Morristown, I-78 divides into local and express lanes. Most access is via the local lanes, though exit 49 (Route 124) includes a direct westbound onramp to the express lanes. Exit 48 was built as the planned western end of Interstate 278, but that road was never built beyond Linden. Even the busy Garden State Parkway interchange (exit 52) only has ramps on the local lanes. There are also no ramps from the Parkway north to I-78 west or the Parkway south to I-78 east; traffic making those movements is directed to enter I-78 going the other way and make a U-turn at the next local interchange. Exit 56, which provides local access to Irvine Turner Boulevard in southwestern Newark, is a large semi-directional T interchange with full access to the local and express lanes. The interchange was built as the south end of the never-built Route 75, which would have connected to Interstate 280 (where unused ramps were also built) and Route 21.

The final interchange on the free part of I-78 is the massive complex at the Newark Airport (exits 57 and 58), with ramps to and from U.S. Route 1, U.S. Route 9, U.S. Route 22, Route 21, and many local roads. Several ramps provide access to the express lanes. Just to the east, the local and express lanes rejoin at the barrier toll for the New Jersey Turnpike and its Newark Bay Extension. An interchange just beyond the toll booth provides full access to Interstate 95, the main line of the Turnpike, and I-78 then rises onto the Newark Bay Bridge into Bayonne. Exits 14A and 14B, numbered as part of the New Jersey Turnpike, provide local access to Bayonne and Jersey City, and exit 14C is the eastern barrier toll (the toll near the Newark Airport is numbered exit 14). After the barrier toll and a recent exit for a Hudson-Bergen Light Rail park and ride, I-78 heads down to surface level and merges with the Route 139 freeway. I-78 and Route 139 head east along 12th Street (eastbound) and 14th Street (westbound) in downtown Jersey City, running through four traffic signals (in violation of Interstate standards) before heading into the Holland Tunnel (tolled eastbound) under the Hudson River into New York City.

In New York City, I-78 continues through the Holland Tunnel plaza. The four separate exits from the tunnel are assigned numbers - exits 1 to 4 - in counterclockwise order. The last one - and the logical continuation east - is Exit 4, Canal Street. Under the original plans, I-78 was to continue across Manhattan as the Lower Manhattan Expressway onto the Williamsburg Bridge, and then beyond I-278 on the never-built Bushwick Expressway through Brooklyn into Queens near the JFK Airport. A section of I-78 at the airport was built as the Nassau Expressway, now Interstate 878, though most of the westbound side was never built. East of the airport, I-78 would have turned north on the Clearview Expressway (built north of Hillside Avenue and now I-295), run across the Throgs Neck Bridge, and forked into two spurs, ending at I-95 via the Throgs Neck Expressway (now I-695) and the Bruckner Interchange via the Cross Bronx Expressway (now part of I-295).

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Major cities

Bolded cities are officially-designated control cities for signs.

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Auxiliary routes

Image:Allentown-Bethlehem, Pennsylvania 1955 Yellow Book.jpg All of I-78's three-digit Interstate spurs serve New York City. Interestingly, since I-78 has been truncated to the east end of the Holland Tunnel, and since I-278 was never completed in New Jersey, none of these routes actually meet I-78.

In northeastern Pennsylvania, I-78 originally used U.S. Route 22. Route 378 into downtown Bethlehem was once Interstate 378, and an Interstate 178 was planned into downtown Allentown.

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References

Template:Ed rightMain 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 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

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