Bayonne Bridge Abutment Rehabilitation
Connecting New Jersey with the Port Richmond area of Staten Island, the Bayonne Bridge is the third longest steel arch bridge in the world. Constructed between 1928 and 1931, the bridge has an arch span of 1,675 feet and an elevated structure length of 6,695 feet. In the 1970s, remedial repairs were made to the North abutment on the New Jersey side. A one-inch shotcrete overlay was installed over the abutment to encase it, but an alkali-silica reaction caused cracks to propagate through the shotcrete compromising the structural integrity of the abutment.
STRUCTURAL TECHNOLOGIES was contracted to be a part of the retrofit / repair team. The repair program included the installation of a cofferdam, removal of existing 3.5-ton granite blocks, concrete removal, multiple stages of concrete encasement, underpinning of the structure, pressure grouting within the abutment, drilling and post-tensioning installation both vertically and horizontally.
The installed post-tensioning tendons ranged in size from 32-0.6″ strands to 60-0.6″ strands for a total of 435 tendons. Concrete placement was performed in two stages — one for bearing of the post-tensioning anchorages and the other for the encasement of the post-tensioning anchorages that would be underwater after cofferdam removal. The pressure grouting program followed the first stage of concrete placement, the purpose of which was to fill any cracks or voids that existed in or immediately below the abutment (bedrock to abutment interface).
The team encountered many challenges associated with working in a cofferdam. Work areas had to be accessed with man-lifts in close proximity with other trades and it was essential to continuously de-water the area to ensure safe and suitable working conditions for man lift and crane access. The bracing added another layer of difficulty during placement of vertical tendons. A 15-ton crane was mobilized on top of the abutment to maneuver the vertical tendons around existing bracing. All post-tensioning materials and equipment required the use of cranes for installation because of the size of the structure.
The repair program provided a long-term solution for the Bayonne Bridge North Abutment and enables this main transportation artery to continue serving the area for years to come.