KEARNY –
Don’t expect to see planes taking off and landing on the new Wittpenn (Rt. 7) Bridge, but its steel deck – still under construction – will be “similar to U.S. battleship decks.”
So says the state Department of Transportation which is supervising the building of an entirely new span just west of the existing 1930 bridge that, in the interim, continues in serve as a Jersey City-Kearny link over the Hackensack River.
Ultimately, the old bridge – already overshadowed by its partly-assembled towering neighbor – is to be demolished after its replacement structure is in place.
The $480 million project, which will include a realigned approach to Fish House Road in South Kearny, began in 2011 and is due for completion by 2020, DOT spokesman Stephen Schapiro said.
Members of the media were recently granted access to the construction site and briefed on the project by Schapiro and DOT staffers.
Motorists straining to keep within the confines of 10-foot-wide lanes (on the current bridge) – there are two in each direction – with no median or shoulder on the existing bridge will be able to ease up a bit with its replacement.
On the new bridge, they’ll still have two lanes each way but each lane will be 12 feet wide, with 8-to10-foot-wide shoulders, one 12-foot-wide auxiliary lane, an 8-foot-wide median barrier and 6-foot-wide sidewalk that can accommodate pedestrians and cyclists.
Like the current bridge, the new one will be equipped with a vertical lift to open for vessels passing underneath but the new one will have a vertical clearance of 70 feet when closed – double the clearance of the present bridge – allowing larger ships to pass and causing fewer disruptions of traffic. The existing 135 feet vertical clearance when raised will remain the same.
The new bridge deck is being designed as “orthotropic” – the first of its kind, Schapiro says, to be built in New Jersey – to be made of a thinner structural steel and lighter weight with a series of longitudinal “ribs” and floor beams supported by floor beams and girders.
Similar construction was used for the decks on the Verrazano-Narrows and Bronx-Whitestone Bridges, a DOT fact sheet says, along with the Golden State with a deck replacement in 1985 and Tacoma Narrows in Washington.
Although it tends to be more costly to build, DOT contends the added expense is justified by less maintenance required for this type deck and a projected 100-year life expectancy.
The deck is being prefabricated by Oregon Iron Works/Vigor just outside Portland and is to be shipped in five sections by boat, via the Panama Canal, and, ultimately, by barge along the Hackensack to the construction site where it’s expected to be assembled in two weeks.
More specifically, as outlined by Schapiro, “The main lift-span portion of the bridge, the orthotropic deck, is to be constructed with three main box girders that are 325 feet long and run longitudinally (same direction as traffic) and two-end floor beams that are nearly 124 feet long and run transversely (perpendicular to traffic) that the box girders are attached to.
“There are 27 floor beams that are 110 feet long that run transversely and 46 trapezoidal-shaped ribs that curve at the bottom that are also 110 feet long and run longitudinally. The deck plate is 325 feet long, 110 feet wide and three-quarters of an inch thick.
“The total estimated weight of the lift-span is nearly 4.9 million pounds.”
There are 15 bridge piers that support the deck and are made of concrete and reinforced with steel. These range in height from about 29 feet to 70 feet.
Schapiro said the new bridge is expected to open “70% less than the current bridge” and should take a bit less time – four minutes vs. the current five minutes – to open.
On an average, the current bridge is opened for ship traffic between 220 and 228 times a year.
To date, contractors have installed the river piers, fender system and east approach spans for the new bridge while the west approach spans, Fish House Road pump station, advance utilities, embankment, new vertical lift-span and towers are underway.
