Investigators in northeast Washington, D.C., Tuesday at the site of the deadliest accident in Metro history began examining why systems designed to keep trains safe failed Monday evening at the height of rush hour.
With nine people dead and 76 sent to area hospitals -- some of whom are critically injured -- the accident site remained a rescue scene Tuesday, with a crane and cadaver dogs brought in to find people who were possibly still trapped on the trains.
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Today investigators said the two trains that collided were likely being run by computers that control speed and braking. Officials said Metro trains travel above sensors along the rail that can automatically detect when trains are getting too close to one another. The computerized systems stops them from coming within 1,200 feet of each other, and investigators need to find out why it didn't work.
"What causes us concern the most is the fact that this was not supposed to happen," said Jackie Jeter, president of Amalgamated Transit Union Local 689 today. "There are safety mechanisms that are on place on the trains to prevent this type of accident. And, for me, as president of the union and as a train operator, I have to wonder why didn't those safety mechanisms kick in and prevent it."
It's still not clear whether the crash was the result of an operator error, a train malfunction, or a problem in the computer system.
"It's much too early to speculate as to what actually happened," former National Transportation Safety Board investigator Barry Sweedler said, adding that investigators will take a close look at the automatic train controls.
Sweedler also said train recorders will provide insight into what happened as the information is evaluated over the next few days. The train that was hit had several recorders on it, but the one that collided into it didn't have any.
No matter what caused the accident, passengers traveling in the approaching train were in an older car that did not protect them as well as it should have.
In 1996, a Metro train of the same series failed to stop and crashed into an unoccupied train in what the NTSB called "catastrophic failure." After the crash the NTSB recommended a comprehensive evaluation of the cars. In 2002, D.C. Metro declined to make any changes. A similar crash took place in 2004, and the NTSB reiterated its warnings.
"In 2006 [the NTSB] asked them to look at old cars," Deborah Hersman, the NTSB investigator for Monday's crash, told "GMA" today. "They did not retrofit the cars to the standard the safety board was looking for."
Hersman emphasized that the NTSB's role was to make recommendations, and that it was up to local and federal authorities to decide whether to act based on those recommendations.
"The Safety Board is in the business of investigating accidents and making recommendations," Hersman said. "The safety board is going to be looking very closely to what has been done."