Investigators focus on D.C. track; stations reopen

WASHINGTON — Commuter rail tracks in the nation's capital are studded with devices that detect passing trains and tell them when to stop or slow down. But those devices on the stretch of track near where nine people were killed in a train crash didn't pass tests by investigators.

Metro reopened two stations Thursday that had been closed since the crash, but only for morning and afternoon rush hour. Trains were running along just one track, leaving the side damaged in the crash closed and under investigation.

The tests Wednesday 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 Board. "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 the testing device, Hersman said. 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, although there is evidence the operator tried to slow it down. Since the crash, trains have been manually controlled as a precaution against computer problems.