Investigators are expected Wednesday to start considering whether human error played a part in Tuesday's crash on U.S. 41, south of Terre Haute. Two investigators from the National Transportation Safety Board are expected to begin their own probe.
One likely subject of inquiry will be Larry Siples, 37, of Brazil, Ind., who was driving the tractor-trailer that crashed into a school bus as it stopped at a highway railroad crossing, sending it plowing into the back of another school bus.
A total of 57 students, 10 adult chaperones and two bus drivers, plus Siples, were treated at hospitals. Most of the injuries were not serious.
Siples, however, suffered internal injuries and was listed Tuesday in stable condition at Sullivan County Community Hospital. So far, state police investigators believe the brake lights on the first bus that was hit were working properly at the time of the accident.
The truck's brakes were operating, too, said officer John Evans of the state police Commercial Vehicle Enforcement Division.
"We can't find anything of the remains (of the truck) that contributed to (it) not being able to stop," Evans said. Investigators are awaiting the results of blood and urine tests conducted on all three drivers to determine if drugs or alcohol were factors in the crash.
Investigators will also try to determine how fast Siples was driving. The speedometer on the truck was stuck between 60-65 miles per hour after the crash, Evans said. But that's not always an accurate gauge of speed, he said.
State police will also try to determine if skidmarks left on the highway were from Siples' truck.