Investigators Find Failed Sensing Circuit Near Crash

SILVER SPRING, Md. (WUSA) -- You deal with blind spots in your car. Now investigators are trying to figure out if an electronic blind spot led to the Metro crash that killed nine people.

Engineers from the National Transportation Safety Board are looking closely at the computerized control relays embedded in the tracks. The system is designed as a fail safe to stop any train that comes within 12-hundred feet of another.

The question now: could the stopped train have been sitting in a blind spot where a 740 foot long electronic circuit had failed.

There are six of these electronic circuits between Takoma and Fort Totten. Five of them have checked out. But a sixth circuit near the crash has problems. Investigators on Wednesday night brought in a six car train to travel that section of track to see if that failed circuit is long enough to hide a stopped train.

The Safety Board says Metro worked on that circuit within the last month. And worked on it last year as well. These electronic relays have been a recurring problem for Metro for years.