Federal investigators looking into the fatal subway collision in Washington turned up an anomaly today in the Metro's early waning system.
A 740-foot circuit, or segment of track, did not check out in tests near Monday's collision site between the Takoma and Fort Totten stations.
It's too early to draw conclusions, National Transportation Safety Board agents say. But they are probing whether the defects in the signal systems contributed to the crash that killed nine and injured 80 commuters during Monday's evening rush.
"Their plan is to follow up on the testing today and bring in a six-car train and see what kind of information they get from the circuitry at that point," said Debbie Hersman, a member of the National Transportation Safety Board.
An onboard computer, apparently in operation at the time of the crash, is programmed to prevent trains from getting closer than 1,200 feet.
Inspectors also reported bluing on the track some 300 to 400 feet prior to the point of collision. It indicates that "some emergency braking might have taken place," Ms. Hersman said.
Passengers on the moving six-car train had reported no sign of braking before impact. The collision drove the standing six-car train 7 feet down the track, NTSB inspectors said.
Inspectors also surveyed businesses in the area to see if any had surveillance cameras that could be helpful in the investigation, but did not find any. But they are urging witnesses, survivors, or anyone with video to contact 866-328-6347.
Federal investigators also recovered a number of cellphones from the accident site and are looking into whether any of them belonged to the operator of the moving train, Jeanice McMillan, who was killed in the accident.
Investigation of a fatal crash between a commuter train and a Union Pacific freight train in the Chatsworth district of Los Angeles in September 2008 turned up evidence that the driver had been texting friends on a cellphone at the moment of impact. Along with work history, medical records, and drug testing, cellphone use is now a routine part of any investigation.
"Most investigations take 12 to 15 months. It's early and nothing is ruled out, says NTSB spokeswoman Bridget Serchak.