NTSB official Mark Rosekind said the train was traveling at 62 mph at the time of the crash, short of the 70 mph speed limit. The speed limit was raised from 40 mph in 2006 to improve efficiency for passenger trains, Union Pacific spokeswoman Raquel Espinoza said.
NTSB investigators have not determined if the gate and other protective measures were updated when the speed limit was raised, Rosekind said. The agency plans to test signals for abnormalities Saturday.
Investigators also found the train's emergency brakes were applied before the accident.
Cameras were on both the lead car of the Union Pacific train and a sheriff's vehicle that was trailing the flatbed truck, Rosekind said. That footage could provide a fuller picture of what happened.
The veterans were on their way to a banquet in their honor at the time of the crash. Their float was inching across a railroad track in Midland when the crossing gates began to lower. Some of those aboard the float jumped off before the train seemed to appear out of nowhere and crashed into the flatbed truck.
In all, four veterans of Iraq and Afghanistan were killed and 16 people were injured. Killed were Marine Chief Warrant Officer 3 Gary Stouffer, 37; Army Sgt. Maj. Lawrence Boivin, 47; Army Sgt. Joshua Michael, 34; and Army Sgt. Maj. William Lubbers, 43.
Five people remained hospitalized early Saturday. In Midland, three people were in stable condition and one in critical. None of the injuries are life-threatening, said Marcy Madrid, a hospital spokeswoman. A fifth person, who had been transferred to a hospital in nearby Lubbock shortly after the accident, is in serious condition.
The Associated Press contributed to this report.