WMATA removes 4000-series railcars in safety concern

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Written by: Ben Vient, Managing Editor
Washington Metropolitan Area Transit Authority (WMATA) General Manager/CEO Paul J. Wiedefeld ordered on November 17 the immediate removal from service of all 4000-series railcars from the lead position of trains following the identification of a potential safety concern involving the vehicle's automatic train control (ATC) system that could result in a "false indication" to a train operator going undetected.

Metro says its "ATC system keeps trains properly spaced and a safe distance from other trains by displaying "speed commands" on a control panel in the operator's cab. When operating in "manual mode," the train operator responds to the speed commands, which indicate the train's maximum authorized speed relative to the train's location and distance from other trains. Train operators receive "zero speed commands" -- indicated by a double zero -- when the train is not authorized to move (i.e. the equivalent of a "stop signal")."

Metro railcar engineers believe the potential exists for an undetectable failure of the 4000-series ATC system control board that could result in improper speed commands being given to a train when a 4000-series car is in the lead position, though they say they believe the potential to be remote.

"Today's action is being taken in an abundance of caution and, while we believe that the risk is small, it is a risk I am unwilling to take," Wiedefeld said. "Everything we do here is going to put safety first, no matter what."

Based on a preliminary investigation initiated today, Metro says "it appears that the 4000-series railcar manufacturer recommends annual testing as a way to mitigate the risk of a false indication. Such testing is not currently done at Metro."

Metro reports it may consider "bellying" 4000-series cars in the center of trains -- similar to 1000-series cars: "The ATC issue identified today is not a risk when the 4000-series cars are not in the lead position."

Metro says "the 4000-series is the smallest and least reliable of Metro's six "legacy" fleets." There are 41 married pairs of 4000-series cars currently in active service, and Metro was already considering retiring all of them by the end of 2017. Metro may further accelerate the 4000-series retirement in light of this newly identified issue.

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