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Escalators used by Metro have history of trouble
Metro's chronic escalator outages prompted interim General Manager Richard Sarles to initiate an independent audit in June of the moving staircases and of elevators.
The assessment by the firm Vertical Transportation Excellence (VTX) covered 30 escalators and nine elevators at the Bethesda, Dupont Circle, Woodley Park and Foggy Bottom stations. The company found a pattern of brake problems.
"All escalator brakes have questionable stopping performance," the VTX audit says. It also found "brake pads worn beyond usable life expectancy and out of adjustment which could result in a unit freewheeling to stop."
Most of the escalators inspected were Westinghouse Modular 100s.
The audit recommended that Metro improve its brake testing and maintenance.
That audit, as well as the discovery of faulty brakes after the L'Enfant Plaza accident and also at the Gallery Place-Chinatown station, led Metro to launch an inspection Nov. 4 of all of its escalator brakes, a review that uncovered scores of other brakes in need of replacement or repair.
A preliminary investigation of the L'Enfant Plaza incident, which occurred as the transit agency experienced record ridership Oct. 30 for the Jon Stewart-Stephen Colbert rally on the Mall, found that the brakes failed to hold the escalator in place after the crowd of passengers on it increased the escalator's speed and caused its motors to shut down.
The increase in speed, known as an "overspeed fault," happens when an escalator starts moving at a rate 10 percent greater than its normal speed.
That triggers a shutdown in power to the motors and the brakes, which are applied when the power goes off.
But two of the escalator's three brakes were compromised. One had worn pads, and the other had oil on the brake shoe, according to Metro.
The result: The escalator slid downward for 18 seconds, as passengers ran off or spilled into a pile at the bottom.
Experts said that worn brakes can occur in all escalators but that the design of the Westinghouse escalator could exacerbate them because it is more difficult to maintain.