25 June 2009
Train collision: Circuit anomaly likely suspect
The control system, the sensors, or the communications links are surfacing as the most likely culprits in a train wreck in Washington, D.C., that killed nine people.
Federal investigators found an anomaly in circuits near the site of Monday’s train collision.
The Wall Street Journal reported National Transportation Safety Board member Deborah Hersman disclosed that fact. She said five of six circuits running between the Takoma and Fort Totten stations in northeast Washington were working well, but tests on a 740-foot-long circuit showed ‘anomalies” that could be consistent with some kind of failure.
Transit agencies nationwide are keeping a close eye on events in Washington, because several of them use similar automatic-control systems. Under these systems, trains are essentially run by computers instead of human operators, though on-board drivers situated in the lead car have the ability to run the train manually and to apply brakes if necessary.
The control network depends upon accurate communication relays among sensing equipment stationed along the tracks, a centralized communications hub, and computers installed in trains.
Various forms of automatic train-control systems have been around for more than 25 years. Among the cities with systems similar to Washington’s are Philadelphia, San Francisco, and Miami, according to Greg Hull, director of security and operations at the American Public Transportation Association, a Washington trade group.
“In automatic mode, the function of the operator is to always be attentive to the track and conditions ahead,” Hull said.