Track sensors to be inspected in wake of US crash

WASHINGTON (AP) — The Washington-area mass transit system will inspect every stretch of its tracks as U.S. government investigators work to determine whether problems found with a signaling system in one area could have contributed to this week's crash that killed nine people.

Metro General Manager John Catoe also said Thursday the agency will start rearranging its trains to put the oldest and structurally weakest rail cars in the middle, instead of at the ends, where they are more vulnerable.

Catoe said he ordered inspections of all 3,000 circuits, or sections beneath the track that include a signaling system. The signals provide critical information to passing trains such as when to stop or slow down. Tests by the National Transportation Safety Board indicated a problem with one of the circuits in the area of Monday's crash.

Officials said they wanted to take measures immediately and not wait until the NTSB completes its accident investigation.

"We have to act and we're taking action," Catoe said. He said Metro hoped to conclude its inspections in a couple of weeks, if not sooner.

Tests by the NTSB on Wednesday raised the possibility that trains passing through a 740-foot (225-meter) stretch where the collision occurred could have had trouble receiving signals to stop or slow down. Officials stopped short of saying whether the circuit was broken, refusing to elaborate on the "anomalies" that testers found. Five other stretches of track in the area of the crash near the Maryland state line showed no problems.

"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."

Investigators were planning to test the track with a six-car train.

An engineering professor who has studied transportation safety said that if sensors failed on the track, it could have contributed to Monday's crash. 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. The operator, he said, "was the last layer of defense."

Since the crash, the NTSB has also criticized Metro for failing to revamp or replace its 1000-series rail cars after previous warnings by the agency. The striking train, which sustained most of the damage in Monday's crash, was made up of those cars, which date back to the 1970s. The cars are not as good at withstanding crashes as later models.

Catoe insisted Thursday that the cars were safe, but said the agency was in the process of putting the 1000-series cars in the middle of trains, and not on the ends, as an added precaution. Metro spokeswoman Lisa Farbstein said later it would not be possible to make that change in every case, but the agency will do it where it can.

Copyright 2009 The Associated Press.