Concrete barriers on Maryland’s bridges and overpasses are not strong enough to withstand impact from large commercial vehicles, traffic safety advocates said.

Police and federal transportation officials Monday were continuing their investigation of the Bay Bridge crash, which killed 57-year-old John Robert Short, of Willards, seriously injured two others and stranded thousands of motorists for hours. The crash left a 15-foot gap in the concrete barrier — which safety advocates said are designed only to accommodate passenger vehicles — that protects motorists from a 30-foot drop to the Bay.