I-495 remains closed in both directions over the Christina River from Terminal Avenue to 12th Street. following a bridge inspection that showed four of the 37 pairs of vertical support columns had tilted as much as four percent out of alignment.
No timetable has been established for a reopening of the bridge as engineers look for a cause. Published reports on Wednesday indicated that dirt left in the area by a contractor may have contributed to the shifting of support columns.
DelDOT issued the following on Wednesday:
After 36 hours of monitoring through tilt sensors on the bridge’s support columns, there has been no significant movement of the columns (less than .02 degrees). The bridge is currently stable, but we still do not know what is going on below the surface; therefore, subsurface investigations are underway.
Because we do not fully know what is going on under the surface, we are investigating a range of options that design around the root causes of the current condition, including the potential soft soils around the base of the piers, corrosion at the steel piles, and compressible soils.
DelDOT has assembled the project team and contractor to explore strategies to get the bridge temporarily supported to restore traffic safely as soon as possible. The soil removal operations that began Monday night will continue until all soil has been removed adjacent to the bridge. The group will continue to gather information about the dimensions of the pile and possible involvement. While it is still too early to reach conclusions, our current priority is to remove the soil. DelDOT began securing the work site and fencing will be installed Thursday morning.
Traffic congestion declined on Wednesday as travelers found other routes. DelDOT’s Traffic Section has completed the design of the temporary traffic signal at the I-495 northbound ramp at Terminal Avenue. June 4, 2014
Transportation Secretary Shailen Bhatt said DelDOT has assembled a team of experts from DelDOT, FHWA, engineering consulting firms, and the University of Delaware.
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.
DelDOT will be setting up a field office and providing t updates on the status of the closure. The agency is also working with the Federal Highway Administration to determine if emergency relief funding is available.
