The accident involved the derailment of seven cars of a freight train that was using the bridge to cross Mantua Creek. Some cars ended up in the water and there was a release of hazardous chemicals. 

The train was made up of two locomotives and 84 cars, seven of which derailed. Four tanks fell into the water and at least one containing vinyl chloride was breached.

The moveable bridge opens to allow the passage of water traffic. The crew has described to NTSB officials how the two locos and several cars cleared the bridge before the collapse. The train then went into an emergency braking application initiated by a loss of brake pressure.

NTSB’s latest briefing has discussed difficulties the train crew had with getting the signalling system to accept the codes needed for clearance to cross the bridge.