Federal investigators with the U.S. National Transportation Safety Board (NTSB) say a train control system, which should have prevented the deadly Washington, D.C., Metrorail accident on June 22 in which nine people were killed, failed in a test conducted on June 25th. In a simulation performed by the NTSB investigators, a train was positioned in the same location as the train that was rear-ended. The system failed to detect the position of the parked train. Investigators did not say what caused the malfunction or whether the system failure was the cause of the crash. However, the test results confirm earlier findings of “anomalies” in an electrical track circuit in the crash area. The results of the simulation indicate that the oncoming train may not have received information that a train was stopped ahead. The steel rails show evidence that the operator of the moving train activated the emergency brakes before the crash. If the train protection system is working correctly, when one train enters a buffer zone between trains the computer will deploy the breaks on the train and force it to stop. During the past decade Metro has had problems with components in its signal system. In 1999, the agency discovered that critical relays were failing prematurely. The relays transmit the signals that automatically control speed, braking, and switches. All Metro trains will be operated manually, instead of by the onboard computers, until an inspection of all 3,000 track circuits has been completed, which could take several weeks.
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Tags: System
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