Ntsb, A Metro Critic, Takes Inquiry's Reins

After the 2004 crash, the NTSB issued an emergency directive taking transit officials to task for failing to train their operators adequately. The agency said the system never anticipated an accident in which a train would roll backward.

The Metro system was back under the NTSB's scrutiny after two incidents in 2006 that left three employees dead. In May of that year, a Red Line train struck and killed a mechanic who had been working on the automatic train control system at Dupont Circle. That November, a Yellow Line train fatally struck two track inspectors in Alexandria, Va.

Last year, the NTSB determined that Metro procedures did not require train operators to run their trains by hand or at slower speeds when workers were in the area. It found that transit system rules permitted workers on the tracks to ask that trains slow down but determined that train controllers discouraged such requests and that workers consequently seldom made such requests.

Hersman said Monday night that the NTSB had assigned nine investigators along with support personnel to the latest collision, the worst in the Metro's history, with at least six fatalities. She said the board would be assisted by other federal agencies, including the FBI's incident response team and the Transportation Security Administration.

Full NTSB investigations can take years to complete, but the agency often decides to issue preliminary findings and recommendations much sooner than that.

Transit administration and the NTSB are working together on the accident investigation, said Metro general manager John Catoe. He added that it was "very rare" for a fatal mass transit accident to occur.

Catoe wouldn't speculate on any kind of a cause. He said there was no indication of foul play.

Baltimore Sun reporter Andrea F. Siegel contributed to this article.