(AP) Federal highway officials have determined that a large dirt pile dumped near an interstate bridge in Delaware caused several supporting columns to tilt.
Federal officials said in a letter to state officials last week that the Interstate 495 bridge over the Christina River in Wilmington appears to have been properly maintained and inspected, and that the damage amounted to "a catastrophic failure from an external cause."
The letter was among the information that state transportation officials provided during a joint legislative hearing Wednesday regarding the closure of the bridge and plans to repair it.
The bridge is a key bypass for East Coast travelers. It has been closed since June 2 after engineers determined that bridge support columns were leaning.