After the April 18 wreck, the train's engineer told investigators he had seen a misalignment of track just ahead and was trying to apply the brakes when the force of the derailment threw him against the cab wall. Four passengers were killed, 36 people were seriously injured, and more than 100 suffered minor injuries.

The National Transportation Safety Board investigators' reports offered no conclusions. Much of the investigation has focused on the condition of the track, which is owned by CSX.

A CSX coal train passed over the track just before the Auto Train took the curve, and that crew told NSTB investigators that they noticed no roughness or irregularity.

But the engineer and assistant engineer of Amtrak's Silver Meteor, which passed over the same area a day earlier, said the track "seemed to be out of line" and caused their engine to rock.

"Both crew members indicated that they mentioned it out loud to each other but didn't believe that it was serious enough to report to the train dispatcher," the report said.