After Fatal Crash, Metro Still Wary of Computer-Controlled Trains
Wednesday, August 19, 2009
Metrorail passengers frustrated with jerkier rides and longer waits for trains after June's Red Line crash can expect those irritations to continue indefinitely as operators run every train in the system manually.
Metro does not have precise data on how much slower the system is moving, but spokeswoman Lisa Farbstein said trains controlled by operators tend to spend more time at station platforms and take more time to accelerate than do trains run by computers.
"You could lose a couple of minutes from one end [of a line] to the other," she said. "If it's 10 seconds between each station, it does add up."
In the weeks since the June 22 crash, in which nine people were killed and 80 were injured, top Metro officials have described continuous manual operation as a safety precaution. But federal investigators have said the automatic control system designed to prevent crashes can be problematic regardless of whether trains are operating under manual or automatic control. The NTSB has said that it appears that Metro's automatic train control system failed to detect a stopped train June 22 and that an approaching train did not receive a command to stop on the track between the Takoma and Fort Totten stations.
Manual control brings with it another set of problems. "Operating a train is a very repetitive task," said Elisa M. Nichols, a transit system safety consultant in Kensington. "You do the same thing all the time. There's complacency. [The operator] could be tired. He could be preoccupied. He could be taking medication. . . . There is nothing inherently unsafe about operating in manual mode, but you introduce more risk."
Metro General Manager John B. Catoe Jr. reiterated last week that trains will not run automatically again until he is satisfied that "all the aspects of what occurred on June 22 have been corrected."
That might take years. The National Transportation Safety Board is probably months away from issuing a final report on the cause of the accident, and making fixes that federal investigators have recommended, such as replacing the oldest cars in the fleet with more-crashworthy ones, would cost hundreds of millions of dollars that Metro does not have. In July, the NTSB urged Metro to install a real-time, continuous backup for the system. Metro began talks with vendors after the recommendation but does not have an estimate for what such a system would cost or how long it would take to install.
The idea behind staying on manual control is that operators will be more engaged in running the trains and can exercise their judgment if something goes wrong. But even with manual control, operators depend on the train control system to tell them how far ahead the next train is. In automatic, the computer sets the train's speed. In manual, the operator sets the speed but does so based on information the computer provides.
"So, inherently, the design problem that caused the accident, if that's what it was, is still present in the system," said Piers Connor, a train systems expert from England who has advised railways around the world. "There is a basic design fault which is inherent in the system, and they've got to design that out."
The amount of time a rider has to wait for a train varies more when the system is on manual. And, like a driver on a congested road, an operator must brake whenever the train ahead is going slower. That contributes to the jerkier rides across the system.
"The automatic train system itself is very precise," said Martin Schroeder, chief engineer for the American Public Transportation Association. "When you have humans trying to replicate that, with their hand on the throttle, it results in longer time between trains."
Because manual operation demands more concentration, the union that represents Metro's train operators is pushing to ensure that members get proper break times. The contract limits operator time at the controls to 5 hours and 45 minutes before requiring a 20-minute break.