WILMINGTON, Del. – Highway engineers say a crucial bridge on the Eastern Seaboard’s interstate highway system could imperil drivers if traffic is allowed back on it.
The bridge, near Wilmington Delaware, was closed Monday when its support pillars where found to be tilting. The bridge won’t reopen anytime soon, highway officials said Tuesday, and the 90,000 vehicles that cross it every day are being diverted onto the main north highway, I-95, further overloading one of the most crowded arteries in America.
It’s the latest crisis involving the half-century-old interstate system.
Engineers say subsurface ground movement appears to have caused supporting columns on the Interstate 495 bridge to tilt. Officials said Tuesday they believe the bridge over the Christina River is stable enough to support itself, but that re-opening it to traffic could overload the structure.
Tripp Shenton, an expert on bridge superstructures and chairman of the Department of Civil and Environmental Engineering at the University of Delaware, said it would be tough to speculate on how close the bridge might have been to collapsing while carrying traffic.
“I don’t know that anybody at this point would be able to answer that, just because they don’t know how quickly this movement has occurred,” he said. “We really don’t know, and the engineers are still doing their analysis to look at the structure as it exists right now.”
Four pairs of 50-foot columns have been found to be leaning, with the top of one column roughly two feet out of line with the bottom. The closing forces more traffic onto I-95, which runs through downtown Wilmington and already is heavily clogged during the morning and afternoon rush hours.
Engineers are conducting tests to determine the exact cause of the problem. No exact timetable for the bridge to reopen has been determined.
“It’s not going to be open anytime soon,” said state Transportation Secretary Shailen Bhatt said in an interview Tuesday with The Associated Press.
An Associated Press analysis of more than 600,000 bridges last year showed that more than 65,000 were classified as “structurally deficient” and more than 20,000 as “fracture critical.” Of those, nearly 8,000 were both – a combination of red flags that experts say indicate significant disrepair and similar risk of collapse.
The now-closed Delaware bridge was classified as “fracture critical.” A bridge is deemed that when it doesn’t have redundant protections and is at risk of collapse if a single, vital component fails.
A section of a Washington state bridge collapsed last year when it was struck by a truck with an oversize load, sending a car and pickup truck into the water. Three people were rescued.
In 2007, a bridge that collapsed in Minneapolis fell during rush hour, killing 13 people and injuring more than 100.
