Experts say they are unsure anything struck the windscreen of an Amtrak train minutes before a deadly derailment in Philadelphia, in another twist to the investigation as the national network restarted its service to New York.
The National Transportation Safety Board has not ruled out the possibility an object may have struck the windscreen but is not certain the train was hit at all before the May 12 derailment, which killed eight people and injured more than 200 others.
FBI agents performed forensic work on a grapefruit-sized fracture on the left side of the windscreen and the NTSB said it found no evidence of any damage that could have been caused by a firearm.
The developments have raised new questions about the events leading up to the derailment, including a conversation an assistant conductor told investigators she heard between the Amtrak engineer and a regional engineer minutes before the train speeded up and went off the rails at a curve.
The assistant conductor said she heard the regional train engineer say he had been “hit by a rock or shot at” and she thought she heard the Amtrak engineer say his train had also been struck.
The NTSB said the regional train engineer recalled no such conversation and investigators listened to the dispatch tape and heard no communications from the Amtrak engineer to the railway’s dispatch centre to say that something had struck the train.
The Southeastern Pennsylvania Transportation Authority said it did not know what caused the damage to its train that night.
Investigators have focused on the acceleration of the Amtrak train as it approached the curve, reaching 106mph as it entered a 50mph stretch and slowing down only slightly before the crash.
Amtrak engineer Brandon Bostian, among those injured, has told authorities he does not recall anything in the few minutes before the derailment.
The NTSB said it could be a year before it determineed the probable cause of the derailment.