DOT's Foxx Cites I-495 Bridge Repair in Highway Trust Fund Warning
The Delaware Department of Transportation closed the bridge in Wilmington after an inspection found four support columns were tilted as much as 4 percent out of vertical alignment.
The I-495 bridge over the Christina River in Wilmington, Del., was closed two weeks ago by the state's Department of Transportation after inspectors discovered four support columns are tilting. Work is under way to repair the structure, and federal DOT has provided $2 million in emergency funding to assist, U.S. Transportation Secretary Anthony Foxx noted in a June 16 post at the agency's Fast Lane blog. He pointed out that the closure affects the main north/south interstate on the East Coast – I-95 – so the closure will cause freight shipments and motorists throughout the region to experience significant delays.
"If you're reading this in Miami or in Maine, you may think that's too bad for folks in Wilmington, and you may wish the Delaware DOT all the best in fixing it. But it affects you, too," Foxx wrote. The closure also affects traffic in and out of the Port of Wilmington, he added. “The good news is that we have already begun helping DelDOT by providing $2 million in emergency funding to get started. And our team at the Federal Highway Administration is standing ready to help," he wrote. "But America has much more infrastructure that needs to be repaired --and much more infrastructure that needs to be built-- than we have dollars available. What we have instead is a Highway Trust Fund that could run out of money in the next two months. Unless Congress acts."
Del DOT reported that stockpiled dirt located near the bridge is suspected of creating lateral subsurface pressure on the bridge pilings. A contractor removed the dirt -- estimated to weigh 50,000 tons – causing the affected piers to rebound slightly (0.26 degrees) toward their original vertical alignment. "This provides evidence that the weight of the dirt could have contributed to the lateral displacement of the soil," according to the agency, which is posting updates on the repairs here.
Its plan to reopen the bridge calls for constructing new, concrete-filled shafts down to bedrock beneath the columns that have tilted out of alignment, with the concrete shafts tied together with a reinforced concrete grade beam. Temporary jacking towers would be erected on the grade beam to restore the bridge superstructure to its original position and lift the weight off tilted piers. Once the bridge has been rendered safe for traffic, permanent concrete columns will be erected. According to the agency, southbound lanes of the bridge could be open as soon as Labor Day 2014, with the northbound lanes would be opened several weeks later.
The bridge was constructed in 1974 and is 4,800 feet long, with 38 spans. No deficiencies were detected during its previous inspection in October 2012, when the dirt stockpile was not present at the bridge, according to Del DOT.