ANY ORGANIZATION is bound to have a few bad apples in its workforce. But the revelation that nearly half of the employees who inspect Metro’s tracks were lackadaisical, even negligent, about their critical work suggests a department that is rotten to the core. So it is about time that officials took aggressive action to stamp out malfeasance that places the public’s safety in jeopardy.

Investigation into the July derailment of a Silver Line train revealed what officials characterized as a pattern of fabrication and negligence by nearly half of the agency’s 60-person track inspection department. Six employees were fired, six more will be subject to pending terminations or suspensions, and a total of 28 workers received disciplinary action. The misconduct went back as far as three years and extended beyond the rank and file to supervisors.

There were thankfully only minor injuries when a train derailed at the start of the morning rush on July 29, but it snarled service for much of the day and closed the East Falls Church station for days. Repairs cost about $860,000. That inspectors, as was determined by the National Transportation Safety Board, knew about flaws in the tracks for as long as a year before the derailment is damning and frightening. So too is the response of the head of Metro’s largest union, who offered weak excuses. “There are a lot of nuances here,” said Jackie Jeter, president of Amalgamated Transit Union Local 689, who, according to Adam Tuss of NBC Washington, also said the union will “probably” fight the disciplinary action.

There is nothing nuanced about the sad state of the Metro system or the part played by a poorly motivated labor force and lax management. If there is an encouraging sign, it is in the forthright actions taken by General Manager Paul J. Wiedefeld, who took over Metro leadership about a year ago. By firing the workers, referring the matter to federal prosecutors for possible legal action and laying it all out for the public, he is doing what his predecessors failed to do. Instead of just giving lip service to safety, he is taking it seriously and sending a message about the urgent need for a cultural change.