Labeled as “the most ambitious, complicated and challenging construction job ever undertaken at this facility,” the 70-year-old Henry Hudson Bridge is undergoing a lower level deck replacement.
The bridge, named for the explorer, Henry Hudson, who anchored his ship near the site in 1609, connects Riverdale in the Bronx with the Inwood Hill Park section in Manhattan.
Work on this $84.3 million project began in September 2006, according to Walter Hickey, Henry Hudson facility engineer of MTA Bridges and Tunnels.
The reason Hickey dubbed the project ambitious, complicated and challenging is because it involves all aspects of engineering, including structural mechanical, electrical and fire safety,” and must be done while maintaining operations and minimizing the impact of travelers.
The work is necessary because of deterioration by the elements and the fact that the lower level deck of this 2,200-ft. (671 m) long bridge “has reached the end of its useful life.”
He said the bridge’s lower level was opened Dec.12, 1936 and the upper level was added in 1938 and replaced in 1998. In 2006, annual traffic count was 24 million vehicles.
Plans call for replacement and rehabilitation of the lower deck roadway and the north approach and involves three distinct areas: the south approach structure, the north approach structure and the arch span and its five viaducts.
The south approach is a concrete structure that houses the bridge’s maintenance garage and workshops. Work for the south approach structure calls for rehabilitating its concrete columns and beams by removing and replacing spalled concrete and beams and adding eight additional steel members to strengthen the south approach.
The north approach contains the bridge’s electrical room, which houses the electrical feeder for the bridge. Plans call for demolishing the north approach’s 15,000-sq.-ft. (457 m) beams and replacing them with a 15,000-sq.-ft. (457 m) steel structure.
“The complicated part here is that the north section of the upper level sits on the top of the north approach’s concrete structure,” Hickey explained, adding “as we remove and replace the north approach, we have to temporarily support the upper level structure with temporary steel columns.”
The north approach structure, which is the elevated portion of the roadway, will not only receive new steel bracing, but it also will get new walls and a new concrete abutment, which supports the end of the span where it meets the roadway.
The reinforced concrete lower level deck of the bridge will be replaced with a steel grid deck filled with concrete.
Project plans also call for replacing the steel beams on each 160-ft. (49 m) high Bronx and Manhattan towers; replacing the power feeder from the north approach; replacing the existing metal halide roadway lighting with new pressure sodium lighting; adding fire stand pipes to both levels of the bridge and doing a seismic retrofit of the bridge’s upper level columns and lower level,” Hickey said.
To maintain traffic and keep the bridge operational during construction, construction will be done in four stages.
During the first stage, which is expected to be completed by the end of 2007, the decking on the right hand lane will be cut into sections, lifted and loaded onto trucks. After the steel work has been completed, a steel grid deck will be put down, filled with concrete and then topped with an additional layer of concrete. This process will be repeated in each of the subsequent three stages.
“The new deck will be lighter and thinner than the old deck and it is expected to have a life expectancy of approximately 70 years,” Hickey said.
The project involves around the clock closure of one southbound lane at a time until the project is completed. A second lane will be closed during the off-peak hours of 10 a.m. to 3 p.m., as necessary to complete the work safely.
In addition to the lane closures, the lower level sidewalk on the west side of the bridge will be closed when deck replacement work begins and will reopen when the work is completed.
The full-length east maintenance sidewalk, which is usually closed to the public, will be opened from sunrise to sunset as a promenade so the community can still enjoy panoramic views of the Hudson River, the New Jersey Palisades, the Harlem River, and Inwood Park. It will be accessible from the east side of the Henry Hudson Parkway at Kappock Street in Riverdale. It does not provide access to Inwood Park in Manhattan.
In keeping with its commitment to the residents who live near the bridge, there will be no nighttime construction work after 6 p.m., no rivet removal before 8 a.m., and weekend construction will consist only of non-noise work such as pulling electric cabling and wiring.
“Our objective is to keep the bridge in a state of good repair, but also be as considerate as possible to our neighbors,” Hickey said.
As a result, work will be done Monday through Friday from 7 a.m. to 6 pm.
Preparation work is well under way. Scaffolding is being erected under the bridge to protect the area from construction debris from above.
“Residents may also see construction workers wearing protective gear working below the bridge on Palisades Avenue near the north abutment,” he said.
In addition, the project’s general contractor is currently installing a steel gantry rail system and mounting it to the upper level, lifting the concrete slabs out of the existing deck and trucking them out to be crushed, Hickey explained.
Project team members include Jacobs Engineering of Manhattan, construction manager; Judlau Contracting Inc. of College Point, N.Y., general contractor; and MTA Bridges and Tunnels of New York, N.Y., owner.
The project is expected to be completed by the spring of 2010. CEG