Investigators look at 'anomalies' in D.C. metro track

WASHINGTON — Investigators are focusing on a stretch of track near the site of a deadly commuter train crash after finding abnormalities Wednesday in vital equipment that detects passing trains and transmits speed and stop commands.

The test results raised the possibility that trains passing through that stretch could have had trouble receiving signals to stop or slow down. Officials stopped short of saying whether the sensors were broken, refusing to elaborate on the "anomalies" that testers found.

"Whether trains are operated in automatic or manual, these circuits are vital," said Debbie Hersman of the National Transportation Safety Boards. "We're particularly interested in the speed commands that might be sent from that circuit when there's a train standing on that circuit."

Equipment along a 740-foot stretch failed to recognize a device that simulates the presence of a train during the tests, said Debbie Hersman of the National Transportation Safety Board, which is leading the investigation. Five other stretches of track, or circuits, in the area of the crash near the Maryland state line showed no problems.

Hersman wouldn't give specifics on what the "anomalies" were or whether investigators think they were occurring before the crash, saying more tests were needed. Investigators planned to test the track with a six-car train Wednesday night.

An engineering professor who's studied transportation safety said that if sensors failed on the track, it could have contributed to Monday's crash, which killed nine people. He emphasized, though, that catastrophic crashes usually can't be blamed on a single factor.

"If the sensors didn't work properly, it deprived (the train operator) of very vital information," said Najm Meshkati, professor of engineering at the University of Southern California. "She was the last layer of defense."

The deadliest crash in Metrorail's 33-year history occurred when a train plowed into another that was stopped. The moving train was operating in automatic mode, which means it was primarily controlled by a computer, though there is evidence the operator tried to slow it down. Since the crash, trains have been manually controlled as a precaution against computer problems.

Hersman said inspectors found 300 to 400 feet of markings on the rails, indicating some emergency braking took place before the crash. Hersman also has said the emergency brake control on the moving train was found pushed down, though it's not clear how or when that happened. The operator of the oncoming train was among the dead.