NTSB: Crew members' sleep likely cause of train collision

The National Transportation Safety Board (NTSB) has determined that two Union Pacific Railroad trains collided in Texas in September 2015 because the crew of one train was likely asleep before the accident occurred, the agency announced this week.

Contributing to the incident near Texarkana, Texas, was the lack of a functioning positive train control system, according to the NTSB's accident brief.

The incident occurred at 12:34 a.m. on Sept. 8, 2015, when a westbound UP train collided into the side of a northbound UP train. The striking train had been traveling west on the Pine Bluff subdivision's main track, while the other train had been traveling north on the Little Rock subdivision.

The trains collided at a diamond crossing of the two subdivisions. Two locomotives of the striking train derailed and seven cars of the struck train derailed. The lead locomotive of the striking train spilled about 4,000 gallons of diesel fuel.

The engineer and conductor of the striking train sustained minor injuries. Neither crew member on the other train was injured.

NTSB officials determined that the probable cause of the accident was the failure of the westbound train crew members to respond to wayside signal indications that required them to slow and stop the train before reaching the Texarkana interlocking.

The crew members could not provide NTSB investigators with detailed recollections for a period of time right before the collision, according to the NTSB report.

"The NTSB believes that both UP crew members [of the striking train] experienced independent fatigue-induced disengagement that caused them to fall asleep while operating the train," the report stated