Photos by Kelli Raboy.

Equipment designed to detect track problems alerted Metro employees to the dangerous condition that led to a train derailing last month, but an employee deleted the information by mistake, according to a report from WMATA on the incident.

According to the report, the Track Geometry Vehicle spits out warnings as it rolls over the tracks if it detects any problems. The worst kind, like this one, are “Level Black.”

However, the machine also reports “Level Black” sometimes when there’s no problem at all. For example, when it goes over a switch, the track geometry there isn’t the same as on straight track, and there will be innocuous warnings. Or a curve is supposed to have a little extra room. A human operator is supposed to interpret the raw data and decide where there need to be repairs.

In this case, the operator made a mistake, and deleted this “Level Black” from his report while keeping in several others which got fixed. The system still stored all of the raw data, but there was no process where anyone else would compare the operator’s list of repairs against the original raw data. Therefore, his mistake meant that nobody else saw the problem, either.

The operator in question and his supervisor both resigned, according to WAMU’s Martin di Caro, and other employees may face discipline.

This problem is different from, but sounds somewhat similar to, one of the problems before the 2009 Red Line crash. There, the signal system would regularly report errors, but so many that workers started ignoring them. After all, nothing had been wrong the last few thousand times that error popped up. Until, that is, something was very wrong.

There, they were ignoring real errors thinking they were normal. Here, the official protocol was to ignore some errors of this type. But it seems like a dangerous situation in any case when staff get used to ignoring errors.

Operators have a list of places where there are exceptions in the system.

Both humans and computers will look at the track data more closely

To deal with this, Metro is adding processes where a supervisor will review the report with the operator after the run and compare it to the raw data. That way, it’s less likely (though still possible) for a real problem to get ignored.

Just doing that sounds risky, since if the Track Geometry Vehicle regularly spits out “Level Black” errors that both the operator and supervisor are supposed to ignore, it’s very easy for them to just get used to ignoring them and gloss over a real one once in a while by mistake.

That’s why it’s nice to see in the report that Metro is also working to write computer code that can know about the usual spots where not-really-errors crop up. If a specific switch or joint always gives the same error, and that error is actually not a problem at all, then rather than reporting one every time which the operator is trained to delete, maybe the system should report it differently, so that the real Level Black errors stick out more.

Metro will also remind staff that the automated machines are supposed to only supplement, not replace, the visual inspections that also happen. It’s easy to stop paying such close attention if you’ve got a machine that can do it, but the machine can fail.

Metro’s track geometry vehicle.

This report is welcome

We’ve been complaining for some time that WMATA top officials just say “we’ve got this” and don’t share much information publicly. This report is much more forthcoming about the details of what’s going on, and while that’s no substitute for having avoided the problem in the first place, at least being open about the findings now is a positive step.

To continue to build trust, riders deserve to also hear more in the future about how well some of these efforts are going. Many of these findings relate to building the “safety culture” that former General Manager Rich Sarles was supposedly instituting.

The public needs some more assurances about how a safety culture is being built, as it happens. We all can hope Metro actually does build up that safety culture and make these processes succeed; given WMATA’s low level of public confidence, continuing to provide more information can help people actually believe it.

David Alpert created Greater Greater Washington in 2008 and was its executive director until 2020. He formerly worked in tech and has lived in the Boston, San Francisco Bay, and New York metro areas in addition to Washington, DC. He lives with his wife and two children in Dupont Circle.