Investigators with the National Transportation Safety Board said Wednesday they had found design flaws in the bridge's gusset plates, which helped tie the steel beams together.

NPR: Officials Warn of Possible Flaw in Nation's Bridges

Dorgan also cited an in-depth study of the bridge's fatigue potential conducted from 2004 to 2007 that recommended two alternatives for the bridge's future -- to add steel plates to reinforce critical parts of the bridge or to conduct thorough inspections of the wells inside the box to determine whether there were cracks.

CNN: Bridge collapse probe focuses on unexplained shift

The scheme would see volunteers patrol the town's bridge, where there is a 17.5 tonne weight limit, to record the registration plates of any offending vehicles.

BBC: Bath lorry ban could impact Bradford-on-Avon