CHICAGO – A sensor for an automatic braking system was too close to the end of the track to prevent a crash at Chicago's O'Hare International Airport, according to a preliminary federal report released Monday.
The National Transportation Safety Board's one-page analysis of the dramatic March 24 crash at the airport's underground station said the Chicago Transit Authority train was traveling at 26 mph when it passed a "trip stop" that activated the emergency braking system.
"Due to the train speed, the distance from the fixed trip stop to the track bumper post was too short to stop the train," according to the report.
More than 30 people were injured when the train slammed into the bumper at the end of the line, hopped onto the platform and scaled an escalator, causing $9.1 million in damage. Authorities have said the timing of the crash, which happened just before 3 a.m., limited the number of injuries because so few people were on the typically busy platform and escalator.
In a statement Monday, the CTA said has taken steps to improve safety, lowering the speed limit for trains entering the O'Hare station to 15 mph. The transit agency also moved the trip stop further back to increase stopping distance.
The driver told NTSB investigators she dozed off in the minutes before the before the crash and had done so on another occasion in February when she overshot another station platform. She had been operating trains for only two months and was an extra-board employee, which means she filled in for other drivers who called in sick or were on vacation.
Her union has said she worked a lot of overtime and was exhausted, a sentiment echoed Monday by the NTSB. The federal agency said the operator had worked nearly 60 hours in the previous week and was working her third-consecutive night shift.
"She told investigators that she had inadequate sleep," the night before the crash, according to the report.
The CTA fired the operator on Friday.
Transit officials said they don't believe her work schedule played a role in the crash, but announced a series of changes that the agency said will make its scheduling guidelines some of the most stringent among the nation's large transit operations.
The investigation into the crash is continuing.