DC Metro signal problems chronic, safety board says

Malfunction is found in area of fatal June crash

By Nafeesa Syeed
Associated Press / July 24, 2009

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WASHINGTON - The signaling system that detects a train on the tracks of Washington’s transit system has been having problems for a year and a half in the area of the crash that killed nine, federal investigators said yesterday.

The National Transportation Safety Board said records show that the system on the track circuit had been intermittently malfunctioning, whether a train was present or not, since a piece of equipment was replaced in December 2007.

The equipment, known as an impedance bond, communicates information such as speed and distance between the tracks, trains, and operations control center. Investigators said earlier this month that a similar piece of equipment at the other end of the same stretch of track had been replaced five days before the June 22 crash and failed periodically before it.

The NTSB is looking to see whether any reports from the past 18 months or records from train operators might have noted problems with the circuit. “Anomalies’’ also have been found on other circuits, the board said, and investigators are trying to find out whether the problems are similar to those near the accident site.

Federal investigators said they also are working to determine whether other factors could have interfered with the automatic train-control system, such as system upgrades and changes.

John Catoe, Metro general manager, said initial sample tests of rush-hour trains from December 2007 until last month when the other impedance bond was replaced do not indicate the circuit failed to detect trains.

“The circuit appears to have been doing the job of detecting trains,’’ Catoe said. He likened the intermittent malfunctioning to lights dimming and then brightening. He said Metro is reviewing all data to ensure the circuit always properly detected trains.

He said Metro checked all of its 3,000 circuits after the accident and found that three had problems; two were in a railyard and the other was in use in the system.

Catoe said recent blips that have been found in circuits do not resemble the magnitude of the track circuit problem found near the accident. But he said the agency has stepped up daily maintenance, with two to four circuits possibly being investigated each day.

Nine people were killed and more than 70 injured when a train slammed into another train stopped on the tracks near the Maryland state line. Catoe said trains will continue to run manually until investigators determine the cause of the accident and the transit system makes improvements and implements its backup system.