"Frankly, we may never know the answers," says George Black, the NTSB member who is chairing the hearing.
Investigators hope to find out whether truck driver John Stokes was trying to drive around the crossing gates and beat the oncoming train. Stokes is not testifying at the hearing. He told investigators soon after the crash that he didn't see the train approaching and that the warning bells, lights and gates didn't activate until after he was on the tracks.
Three people who were close enough to the accident to give investigators detailed testimony have come forward and are being re-questioned at the hearing. During the first day of testimony Monday, those eyewitnesses gave conflicting reports.
Luis Nieves, who says he was driving the second of two cars stopped behind the truck, said he saw warning lights and heard bells as the trucker drove through the railroad crossing. He said he also saw a crossing gate strike Stokes' truck as he tried to drive it around the barrier, shortly before it was hit by the train.
However, truck driver Aubrey Fosburgh, who was picking up cargo about 75 to 100 yards from the crash site, said the crossing gate was up when Stokes crossed the tracks, and that he never saw the gate go down.
Yesterday, John Sharkey, a communications and signals general manager for the railroad, testified that he investigated the crossing gate at the crash site and saw no markings indicating that it hit the truck.
The board has been unable to locate two people who other witnesses say were in a vehicle just behind the tractor-trailer loaded with steel that drove onto the grade crossing and caused the train to derail, killing 11 people.