A New York subway train derailed earlier this week, injuring thirty-four riders and striking fear into the hearts of subway riders who had believed their biggest concern was subway delays, not injury or death on the way to work.

Thankfully, after only two days, and without even having to conduct a lengthy, troublesome, expensive investigation, the Metropolitan Transit Authority has solved the case, found the cause, identified the culprits and fired them: “Subway officials blamed the derailment on human error and suspended the two supervisors without pay.”

Case closed. Right?

Not so fast. As avid readers of Confined Space understand, resolving safety issues is not as simple as finding a couple of workers to blame and getting rid of them. Because if you don’t identify the root causes of a problem, everyone may feel a lot better for a while, but the problem will inevitably repeat itself.

Resolving safety issues is not as simple as finding a couple of workers to blame and getting rid of them

In this case, the immediate cause of the incident was a leftover 13-foot piece of rail that was left in the tracks to be picked up later and taken to a rail yard. But the MTA’s new chairman, Joseph J. Lhota, argued that rules had been broken. Although storing equipment between the tracks was a common practice in the railroad industry in order to make repairs more quickly, the rules say that any piece of rail less than 19 feet 6 inches must be removed.

According to Lhota, it’s simple: “The rules are the rules, and they didn’t follow the rules.”

Not everyone agreed:

New York City’s subway has for decades stored such equipment in the tracks, using a rail spike to fasten the rails to the wooden railroad ties, said John Samuelsen, the president of Transport Workers Union Local 100, which represents subway workers. The rails are left in the tracks until a train can pick them up and take them to a rail yard — a decision that is made high above the level of subway workers.

“The decision not to have the rail collected by a work train was a decision by management,” Mr. Samuelsen said. “It is oversimplifying the tragedy by calling it just human error on the part of the supervisors.”

Note that the fired workers were supervisors and Local 100 doesn’t represent them. But Michael Carrube, president of the Subway Surface Supervisors Association, which does represent the two suspended supervisors, agreed: “It’s horrendous to point the finger and take someone out of service prior to the completion of the full investigation.”

Blaming workers instead of identifying the real causes of incidents has a long an dishonorable history, highlighted by the 2005 Texas City BP explosion that killed 15 workers and was initially blamed on “surprising and deeply disturbing” mistakes by refinery workers, to another New York transit incident in 2003 in which a supervisor was blamed and fired — as well as the cases I’ve written about more recently.

What we have here is a common phenomenon in “blame the worker” stories: a rule on the books that is rarely or never followed, but no one is punished for not following the rule until a major incident occurs. The other problem that we have here is a failure to do a root cause analysis that will get us beyond blaming the worker for the immediate cause of the incident.

Crucial to any root cause investigation is one word: “Why?” Investigators need to keep asking “why?” until the root causes are identified. For example, why didn’t workers follow the rule about not leaving short pieces of rack on the track? Were they lazy and incompetent? Were the rules normally followed to the letter, or were they generally ignored or circumvented?

You don’t restore confidence in the system if you lose the confidence of the system’s employees by blaming them for an potentially deadly incident without conducting a thorough investigation.

The problem with labeling the cause of incidents like this as “human error” is that it leads to the assumption that you can just replace the workers who didn’t follow the rules with different, perhaps more conscientious, less error-prone workers, and everything will be fine. But if you do that without identifying and changing the underlying cause — in this case the fact that no one apparently followed the rules in the book — the exact same thing will happen to the next group of workers faced with the same situation.

So what’s the truth? What’s the real cause? Who knows? We don’t know for certain whether Lhota is correct in blaming the workers, or whether the union is correct in saying that everyone followed the unwritten rule that management ultimately decides when rails are left on the track and when they’re picked up. The only thing we do know at this point is that there hasn’t been any investigation yet and it’s way too early to come to any conclusions that reflexively blame the workers for something that may have been caused by more systemic problems.

According to the Times, “Mr. Lhota, who was named chairman last week, said he was working to restore confidence in the system.”

Well good luck with that. You don’t restore confidence in the system if you lose the confidence of the system’s employees by blaming them for an potentially deadly incident without conducting a thorough investigation.