NTSB Identifies Signal Failure in DC Crash
WASHINGTON — The National Transportation Safety Board (NTSB) has issued nine safety recommendations, six of which are urgent, as part of its investigation into the collision between two Washington Metropolitan Area Transit Authority (WMATA) trains on June 22, 2009. The trains crashed on the Red Line near the Fort Totten station in Washington. The NTSB’s recommendations address concerns about the safety of train control systems that use audio frequency track circuits, authorities said. As part of its investigation, the NTSB said it discovered that a failure occurred in which a spurious signal generated by a track circuit module transmitter mimicked