Footage from a security camera at the Federal Center SW Metro station captured a fire that happened on the tracks. The fire was caused by an arcing insulator. (WMATA)

A YEAR ago, as federal investigators tried to unravel the smoke incident in a Metro subway tunnel that killed one passenger and sickened dozens of others, it emerged that the transit agency’s Rail Operations Control Center was riddled with problems ranging from inadequate training to antiquated computer software.

Now comes word that the same control center, based in Landover, failed to notice or take timely action Thursday after a fire and an explosion — yes, an explosion — on the tracks at the Federal Center SW station. Despite the fact that the fiery blast propelled metal and ceramic shrapnel onto the tracks and platform about two seconds after a train had left the station, Metro personnel at Federal Center SW shrugged off the incident and the control center did nothing for hours, even after inspectors requested a power shutdown so they could examine the damage.

For passengers wondering what it means that Metro’s “safety culture” is in tatters, last week’s incident at Federal Center SW is illustrative. It is also proof that the National Transportation Safety Board was not exaggerating when it criticized Metro last week for not having learned lessons from past accidents, including fatal ones.

One question is whether Metro has replaced the software at the control center, which until recently generated such an incessant stream of alarms about smoke and other incidents that subway controllers simply tuned them out. We asked Metro; no answer yet.

Another question is whether Metro has initiated disciplinary action as a result of recent serious mishaps, including the sluggish response at Federal Center SW. According to Paul J. Wiedefeld, Metro’s general manager, neither the operations supervisor at the station nor control center personnel were at first aware of the extent of the explosion or the resulting hazard and assumed it was nothing more than a routine (for Metro) mishap.

That’s astonishing. How could the supervisor on the scene have failed to detect the aftermath of an explosion that left shrapnel on the tracks and platform, or shrugged off the event? That lapse enabled trains with passengers to continue traveling over the tracks for hours, until a second smoke event — evidently caused by debris from the morning’s explosion — finally prompted the control center to allow power to be cut along the track.

The complacency of Metro’s initial response, which may have endangered lives, should not be shrugged off. Notwithstanding the agency’s cumbersome procedures for disciplining employees, Mr. Wiedefeld must act in order to send a credible message of accountability to the system’s labor force and passengers.

The general manager, who took up his position five months ago, should also insist on streamlined disciplinary procedures as part of the new contract with Metro’s main transit workers union. The current contract expires at the end of June , and negotiations on a new one are set to begin in coming weeks.

Mr. Wiedefeld, like his predecessor, Richard Sarles, has promised aggressive action — in Mr. Wiedefeld’s case, a year-long maintenance blitz that will cause major disruptions — to restore Metro to a state of good repair. But as the Federal Transit Administration has noted, his plan “does not fully tackle many of the serious safety issues facing the system.” An overhaul in Metro’s culture is what’s needed; that begins with accountability.