In an urgent recommendation made in July, the National Transportation Safety Board (NTSB) urged the Washington Metropolitan Area Transit Authority (Metro) to install backup safety technology to its automated train control system following June's fatal crash involving two Metro trains.
"While the NTSB is still in the very early stages of its investigation into this tragic accident here in our nation's capital, we have concerns about the failure of [Metro's] train control system to prevent this collision," said Mark V. Rosenker, the NTSB's acting chairman.
With the investigation continuing, Metro officials have begun searching for vendors with expertise in backup safety technology for the automated train system, but a timetable for its deployment is undetermined because of the uniqueness of such a system.
"What the NTSB recommended is not something that you can buy at the hardware and install on your computer system. It would have to be something that would be tailor-made and built from scratch," said Metro Public Affairs Specialist, Steven Taubenkibel.
The accident, which occurred on June 22 when one Red Line train plowed into the rear of another stopped on the track, killed nine people and is the first Metro crash in 33 years. The NTSB has focused its investigation on a faulty circuit on the tracks that is part of the automated system for the trains. That circuit periodically lost its ability to detect trains after June 17, the day the part was replaced, the NTSB said July 1. Further testing showed that the circuit was still faulty even after it was again replaced. Although the problem can be replicated, investigators have not been able to isolate the specific cause.
The NTSB has agreed to allow Metro to initiate an independent panel of experts in signal systems through the American Public Transportation Association before its investigation has been completed. This effort will include an independent review of critical components such as signals and circuitry. The final findings will not only be important to Metro, but also to transit agencies across the nation, especially for those that use the same or a similar type of system.
Service on the Red Line was immediately impacted, but had begun to run at almost full strength by early July. Metro also took further preventive measures, including running its trains manually until further notice and inspecting all 3,000 of its track circuits throughout the rail system.
"We are running daily computerized tests on all of our circuits and everything else seems OK but, be that as it may, we're not going back to automatic as of yet," said Taubenkibel.
Metro is also looking to replace its Series 1000 railcars, which were involved in the accident, as soon as possible once specific funding is identified and available, according to Taubenkibel. In the meantime, the Series 1000 railcars were placed in the center of its trainsets.
As part of its recommendation, the NTSB also urged the FTA to advise all transit operators with automated train monitoring systems to evaluate safety redundancy. Taubenkibel explained that it will probably take some time until the NTSB's investigation yields results.
"We are cooperating with the NTSB. They have not completed their investigation, they're still at the scene and still doing their tests of circuits in the area as well as gathering additional data as part of their investigation," he said. "As long as they are out there, of course, we will cooperate with them, and we know it will take several months to possibly a year before they determine a final cause."