A Union Pacific train plowed into a parade float Nov. 16 at a rail crossing in Midland, Texas, killing four wounded veterans and injuring 16 others.
The train was sailing down a controversial stretch of track at about 60 miles an hour.
Federal investigators said it was not speeding.
On board recording devices clocked the lead locomotive at 62 mph, a spokesman for the National Transportation Safety Board said. Investigators say that stretch of track, through the town of Midland, has a 70 mph limit.
The full-length train had about 80 cars that carried shipping containers, according to several news reports.
A witness told ABC News that sirens from the police cars in the parade may have drowned out the sound of the approaching train.
The veterans were on their way to a banquet in their honor at the time of the crash.
The train speed limit at the crossing was raised from 40 miles an hour in 2006, according to ABC News, who cited a Union Pacific official. NTSB investigators are checking to see if the gate was updated at that time, ABC reported.
Veterans and their wives were sitting in chairs on a flatbed semi-trailer. As the truck rolled slowly across the tracks, the crossing gates came down on the trailer, witnesses said. People jumped from the float. Two men pushed their wives off the trailer and were killed. Some veterans were disabled and could not get off the truck in time, according to news wire reports.