Wilmington, Del. — The Delaware Department of Transportation (DelDOT) closed I-495 in both directions over the Christina River on Monday evening, June 2. Bridge 1-813, built in 1974, is 4,800 feet long with 38 spans. The bridge was last inspected in October 2012, and showed no deficiencies. Monday's inspection showed four of the 37 pairs of vertical support columns are tilted as much as four percent out of vertical alignment.
The closure is necessary to assure the safety of the motoring public," Transportation Secretary Shailen Bhatt said. "We fully understand the significant regional impact this closure will have on traffic and are working with our regional partners to do what we can to mitigate the situation. These steps will include adjusting signal timing, utilizing Delaware State Police where needed and designing a temporary traffic signal at Terminal Avenue."
Secretary Bhatt said he has assembled a team of experts from DelDOT, FHWA, engineering consulting firms, and the University of Delaware to investigate, monitor, and determine a path forward.
Tilt monitors were installed last evening to measure any further movement. Over a 12-hour period, the monitoring data from the tilt sensors was inconclusive as to whether additional movement has occurred.
AECOM, DelDOT's bridge design consultant and geotechnical experts, are working together to try to determine the potential causes for the rotation of the support columns. According to AECOM, their preliminary analysis shows the bridge can bear its own weight, but could exceed capacity under a full traffic load. This is why the bridge is closed.
Pennoni Associates has been inspecting the overall bridge and so far no other distress to the structure is evident.
While the investigation and monitoring continue, DelDOT is working with AECOM to design a temporary brace for the bridge, including shoring up and leveling the deck.
The bridge will remain closed indefinitely. DelDOT will be setting up a field office and providing frequent updates on the status of the closure. We are working with the Federal Highway Administration to determine if emergency relief funding is available.