I-495 bridge in Delaware closed due to tilting columns

The I-495 bridge over the Christina River was closed after it was discovered columns were tilting. (AP Photo)

DOVER, Del. (AP) - The I-495 bridge in Delaware that was closed because of concerns over stability won't reopen anytime soon, the state's transportation secretary said Tuesday, with the shutdown causing traffic headaches for motorists along the East Coast.

Engineers believe the Interstate 495 bridge over the Christina River is stable enough to support itself. But they're concerned opening it to traffic could overload the bridge that has four columns that are tilting, state Transportation Secretary Shailen Bhatt said in an interview Tuesday with The Associated Press.

"It's not going to be open anytime soon," Bhatt said.

The emergency closure created heavier-than-normal traffic conditions for motorists on a major East Coast artery, Interstate 95, though no major problems were reported. The bridge normally carries about 90,000 vehicles a day, routing traffic around Wilmington and freight trucks to the port of Wilmington. The closing forces more traffic onto I-95, which runs through downtown Wilmington, and already is heavily congested during the morning and afternoon rush hours.

Workers placed sensors on the four columns Monday to help engineers determine whether they are still shifting. Crews have excavated around some columns and were checking soil beneath the columns.

Delaware officials put up message boards and were working with their counterparts in surrounding states to help get the word out.

"We're basically letting from Florida to Maine know that this issue is going on in Delaware so that trucking interests can be made aware," Bhatt said Monday evening. "You can't take 90,000 vehicles and just shift them onto 95 and not expect to have an impact."

Bhatt suggested that motorists traveling south from New York stay on the New Jersey Turnpike rather than getting on I-95. They should cross into Delaware over the Delaware Memorial Bridge south of Wilmington and then get back on I-95. Similarly, motorists traveling north can stay on I-95 through Wilmington or take Interstate 295 into New Jersey and bypass northern Delaware.

Officials said I-495 is closed northbound at Terminal Avenue, which leads to the port. Southbound traffic ends at the Pennsylvania state line, with traffic diverted onto I-95. Southbound port traffic is being directed to I-295 east and then to Delaware 9 north to the port.

Officials said the four columns on the south bank of the river are tilted by as much as 2.4 degrees, or 4 percent, from vertical. The bridge will be closed until officials can determine what caused the tilt and what must be done to address it.

"The whole bridge will be re-inspected," said Rob McCleary, chief engineer for the Delaware Department of Transportation.

Delaware transportation officials said the agency got a report late Friday from an engineering firm working on an unrelated project about a possible bridge problem and dispatched an inspection team Monday morning.

"It didn't come to us as like an emergency call," Bhatt said, explaining why a team wasn't sent earlier.

Officials said the main span of the bridge over the water is considered "fracture critical," meaning that failure of one element could result in failure of the entire bridge, which consists of a concrete deck on steel beams supported by 37 reinforced concrete columns. However, the tilting columns in question support a different area of the 38-span bridge.

Built in 1974, the bridge is scheduled for inspection every two years and was last examined in October 2012.