ONLY DAYS after Metro's chief executive pledged to shake up the subway system -- with special attention to the accident-prone Red Line -- a train wreck in a tunnel between the Woodley Park and Cleveland Park stations sent passengers fleeing for their lives yesterday. Were it not for the swift heroics of one train operator, passengers noted, the crash could have been deadly. Calvert Sawyers, 58, a 26-year Metro employee, looked up and spotted the lights of another train rolling toward his -- at a speed that would reach 30 mph.

Mr. Sawyers said he immediately opened the doors of Train 105, which was poised to head into the tunnel, got out on the platform and shouted, "Everybody off this train as fast as possible. Run if you have to!" Passengers made it a point later to praise the shaken conductor, noting that he stayed to make sure everyone evacuated with dispatch. The runaway train, No. 703, which had no passengers, then slammed into the stopped train, hurtling up and over the stationary train with enough force to land on its roof. The crash sheared the aluminum shell off one car. Everyone reportedly was spared serious injury, although a number of riders were treated at hospitals for bumps and bruises.

Something -- and it will be up to the National Transportation Safety Board to find out -- failed seriously on a line plagued by breakdowns. What happened to the braking mechanisms? The Red Line is the oldest in the system, but that doesn't excuse a thing. Given Metro's administrative and equipment troubles, a wary public needs to know as much as possible about what's going wrong. Was human error -- either along the rails or in the management chain -- a factor? What new safety measures are in the offing and when? As we said in this space just yesterday, regaining public confidence requires vigorous, immediate efforts. The crash makes remedial measures all the more urgent. Every inch of track, every piece of equipment and every safety-check procedure in the books need review.