As for the periodic failures of the detection equipment, Mr. Catoe said analysis after the accident showed that the failures were “a few seconds” long and would not have been easily noticed by controllers in the system’s control center.  The safety board’s announcement was not entirely a surprise, given its statement last week that investigators had found “anomalies” in one circuit, or stretch of track, in the area near the crash. Equipment along each circuit receives signals that generate speed commands for the trains.  In subsequent testing over the weekend, the train-detection system “intermittently failed,” the safety agency said.  The crash was the deadliest in the history of the Metro system, which links the District of Columbia with the Maryland and Virginia suburbs. The Metro system opened in 1976, and, while it is young by the standards of some big-city transit systems, some transportation experts have said that much of its equipment is outmoded or becoming so.  City officials and leaders of the transit system said last week that a lack of money was the main reason the Metro had not heeded federal warnings to phase out older train cars. Despite financing problems, they said, they did put out requests for proposals for replacement cars.  Metro’s 1,150-car fleet includes 300 of the 1000-series cars, built in the 1970s. The average age of cars in the system is 19.3 years. Officials have said that replacing them would cost almost $1 billion.  Metro officials say revenue from fares and advertising do not come close to covering the costs of the transit system. The Metro agency appeals every year to the District of Columbia, Virginia and Maryland for money, a situation that makes long-term planning difficult.
Equipment that is supposed to detect stopped trains on Washington’s Metro system was repaired five days before a deadly derailment, the National Transportation Safety Board said.