N.J. & PA. Turnpike Bridge is Worse than Feared
By Eric G Braun, Senior Writer, USRW
The Delaware River Turnpike Bridge connecting Pennsylvania and New Jersey on Interstate 276 must remain closed to traffic for a minimum of eight more weeks — at least through early April — according to an emergency engineering task force being co-led by the Pennsylvania Turnpike Commission (PTC) and the New Jersey Turnpike Authority (NJTA), joint owners of the 1.25-mile-long bridge.
The task force, made up of about two dozen public and private engineering design, construction, and transportation entities, reported today that an April reopening represents the best-case scenario which doesn't involve a more complex partial reconstruction of the impacted portion of the bridge or possibly even replacement of the entire structure.
“We recognize that those who travel through, live, or work in this region have been considerably inconvenienced by this closure, and we are as excited as anyone to see it reopen,” said PA Turnpike Chairman Sean Logan. “But please remember, this is an emergency situation; we’re working around the clock to resolve it. It would be reckless to put a single vehicle back onto this structure before we trust its stability.”
The engineering task force has been preparing for several possible repair scenarios; both the PTC and NJTA hope that the least-protracted construction method will be effective.
"Right now, that best-case scenario entails repairing the I-beam by constructing a permanent splice to reconnect the fractured section," said PTC Chief Engineer Brad Heigel. "But before that can occur, crews must first realign the bisected segment by deploying eight temporary towers and hydraulic jacks to return the span to its original position."
Heigel explained that the fracture caused the section of the bridge between the two supporting piers to drop by about two inches when the load being carried by the fractured I-beam was suddenly transferred to the adjoining structural components. Critically, these components were not designed to carry a heavier load; hence, the prompt closure of the bridge.
Crews began to lay the groundwork for the jacking towers last week by drilling piles — grouted steel pipe columns installed underground — to provide a solid foundation for eight, 80-foot towers that will, when the meticulous jacking process is completed, support the entire weight of the impacted portion of the bridge to allow a new splice to be installed and tested.
"The goal of the jacking operation is to return the bridge to its original position and allow us to complete a permanent splice of the fracture. As the jacking operation occurs and load is transferred within the bridge, instrumentation will monitor the actual loads, stresses and displacements which will be compared to estimated outcomes from computer models,” Heigel explained. “This monitoring — which involves affixing about 50 sensors to the structure — is the only way we can confirm that the splice is successful before we reopen the bridge.”
The data gathered during load testing will also enable the engineering task force to determine if a more comprehensive repair is needed before the both the PTC and the NJTA, along with their engineering consultants, are confident enough to reopen the bridge, which has been closed since Jan. 20.
“If more extensive repairs would be required, it is not possible to offer even a rough estimate on the scope or duration of further construction because we simply do not have adequate information to make that projection,” Heigel said.
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