The National Transportation Safety Board (NTSB) says the electrical system designed to prevent Washington, D.C., Metro trains from crashing was inadequate and called on the U.S. Federal Transit Administration (FTA) to install a real-time, continuous backup that would notify train operators of potential problems and halt trains when necessary. In addition, NTSB recommended that the FTA advise other transit agencies that use similar automated systems that they must have adequate safety redundancy and confirm that those agencies take the required action to guarantee that the backups are deployed. NTSB found that the June 22 fatal crash of two commuter trains demonstrated the vulnerability of Metro’s train control system to a single-point failure. The system depends on track circuits to maintain a safe distance between trains, using audio frequencies transmitted between the train and the rails. Federal investigators and Metro officials said the track circuit where the collision took place was intermittently unable to detect a train following the replacement of a key component five days earlier. It was the probe’s conclusion that Metro had “no automatic monitoring” that would identify and immediately report that a train was no longer being detected, while communication between the train operators and downtown controllers in Metro’s operations control center did not take place prior to the crash. The track circuit has continued to malfunction despite the replacement of all its components, and Metro Board Chairman Jim Graham called on the NTSB to find out why. The NTSB said additional software or circuitry could be created to spot problems in real time and inform workers when such problems are detected, while Metro said that there currently are no commercially available systems that could give the FTA the kind of advisories recommended by the board. “We will be developing a new system that will be specifically tailored to Metro,” Metro officials said.
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