Federal safety investigators believe a false signal may have led to the fatal June Metro crash and issued “urgent” warnings for subways and railroads nationwide to inspect their tracks.
The National Transportation Safety Board said it found problems with an audio signaling system for controlling trains that may have caused two Red Line trains to crash on June 22, killing nine people and injuring dozens.
“Our findings so far indicate a pressing need to issue these recommendations to immediately address safety glitches we have found that could lead to another tragic accident,” NTSB Chairwoman Deborah Hersman said in a written statement.
The investigators said that equipment dating to the 1970s when the Red Line was built sent a “spurious signal” that mimicked audio frequencies sent by the rail operating system. That false signal fooled an automatic train safety system into thinking a section of track outside the Fort Totten station was empty.
On the day of the crash a train running automatically slammed into another train stopped on that section of track. The operator pulled the emergency brake but she was killed, as were eight of her passengers.
It’s not clear how many other transit systems and railroads use audio frequency signaling systems like Metro, as neither the Federal Transit Administration, nor the Federal Railroad Administration had firm numbers late Tuesday.
The railroad regulators estimated that only a small proportion of the nearly 700 railroads the agency oversees use such signaling systems. Still, the administration said it plans to help any railroad with those systems find solutions.
The FTA, meanwhile, sent a letter Tuesday night to all the transit systems as a preliminary warning until it can survey them to find out which use similar systems.
The NTSB sent the warning letters with nine recommendations to Metro, the Federal Transit Administration, the Federal Railroad Administration and Alstom Signaling that manufactured the equipment for Metro. The board can make recommendations but not force agencies to follow them.
It’s not clear how many other transit systems and railroads use audio frequency signaling systems like Metro, as neither the Federal Transit Administration, nor the Federal Railroad Administration had firm numbers late Tuesday.
The railroad regulators estimated that only a small proportion of the nearly 700 railroads the agency oversees use such signaling systems. Still, the administration said it plans to help any railroad with those systems find solutions.
The FTA, meanwhile, sent a letter Tuesday night to all the transit systems as a preliminary warning until it can survey them to find out which use similar systems.
The NTSB sent the warning letters with nine recommendations to Metro, the Federal Transit Administration, the Federal Railroad Administration and Alstom Signaling that manufactured the equipment for Metro. The board can make recommendations but not force agencies to follow them.
The board urged every rail system to inspect their signaling system if they use similar audio frequency track circuits to control trains. They also said those agencies and companies need to build systems to assess those controls periodically.
Metro General Manager John Catoe said that his agency “began to do so weeks ago.”
The transit agency is working both with the manufacturers to fix the problems and an outside company to build a system to find the problems in real time.
The federal board, however, said it has not finalized its investigation into the crash, nor found the probable cause of it.
“The NTSB has identified a symptom of the problem with the track circuit, but not a root cause or a solution,” Catoe said. “We will continue to cooperate with the NTSB and respond quickly in hope that they can identify a root cause or causes that will allow us to put steps in place to prevent this from happening again.”
