WASHINGTON (AP) — One of the first sources of information officials investigating an Amtrak train that derailed in Philadelphia will turn to is the train's event data recorder, also known as its "black box."

The nondescript metal container records train speed, throttle position, whether the brakes were applied and what degree of pressure was used, and whether the horn was sounded, said Bob Chipkevich, a former head of railroad accident investigations for the National Transportation Safety Board.

Emergency personnel gather near the scene of a deadly train wreck, Wednesday. (AP Photo/Mel Evans)

"NTSB will certainly go into this accident investigation with an open mind," he said. "They'll look at all the factors that could have contributed to it."

If the train had a forward-facing video camera on the exterior of the cab, which many trains do, that may also yield key evidence such as whether anything was on the tracks before the derailment or whether there were kinks in the track caused by excessive heat, he said. The video cameras often record sound as well. Investigators can determine if there was broken track by the sound a train's wheels make as they cross the track, he said.

Other areas investigators will examine are the track structure, including the condition of the rails and rail ties, and the inspection history of the track. The mechanical condition of the cars will be examined, including the wheels and the axles. Investigators will also examine how well — or how poorly — the cars withstood the crash. And they'll also look at how passengers were injured and whether there are any design components of the cars or lack of safety features that contributed to those injuries.

Amtrak Train 188, a Northeast Regional, was traveling from Washington to New York Tuesday night when it left the track as it navigated a curve in the working-class Port Richmond section of Philadelphia, scattering all seven cars, including the engine. At least six people were killed and 200 injured.


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