A DISABLED RED LINE TRAIN wreaked havoc with the rush hour commute Thursday night, but you’d never know it from reading the next day’s MBTA performance dashboard.

The online dashboard indicated reliability, or on-time performance, overall on the Red Line Thursday was 92 percent – 94 percent during peak travel times and 92 percent off-peak. On-time performance for the subway system as a whole was 86 percent on Thursday.

Asked about the apparent discrepancy between the dashboard numbers and the long waiting periods on train platforms, T officials said they discovered a glitch with the performance database that caused the Red Line numbers to be much rosier than they actually were. Indeed, the glitch had the effect of tossing out the Red Line’s worst performance of the day.

Laurel Paget-Seekins, director of research and analysis at the T, said when the performance database didn’t see trains moving for more than 30 minutes in the train-tracking system it couldn’t tell whether the data was missing or the trains weren’t running. Lacking that information, the automated system removed that gap in calculating the dashboard’s reliability metric, eliminating the delays associated with the rush-hour snafu and making the numbers look a lot better than they actually were.

Paget-Seekins said the glitch was noticed Friday morning and her staff manually compiled the information needed to correct the numbers. The new data indicate on-time performance overall on the Red Line Thursday was 83 percent, not 92 percent. The peak number was 73 percent instead of 94 percent, and the off-peak number was 91 percent, only 1 point down from the earlier reported 92 percent. For the subway system as a whole, on-time performance Thursday was 83 percent instead of 86 percent.

The MBTA’s target for on-time subway performance is 90 percent.

According to an MBTA spokesman, the Red Line began experiencing problems Thursday night at 5:42 p.m., when a southbound train lost power just outside of Charles/MGH Station. Efforts to restore power failed, so at 6:15 p.m. another train was brought in to push the disabled train into the station so passengers could be offloaded. At 6:26 p.m., the disabled train was pushed toward Cabot Yard in South Boston to get it off the mainline so regular service could resume.

The T updated its Thursday performance dashboard information late Friday afternoon. Officials said they  will manually correct any problems that arise in the future and work on ways to improve the automated calculation.

T officials say they haven’t experienced an unusually high number of breakdowns this past week, but the breakdowns that have occurred have come at the absolute worst times – typically at rush hour. On Wednesday, for example, a Red Line train became disabled at 5:46 p.m. at South Station.

“Battered by a major snow storm and the coldest stretch of weather in a century, the aging subway cars took a beating last week,” a T spokesman said in an email on Friday. “T personnel will continue to do everything they can to keep these decades-old trains operating in a reliable manner until they are replaced with the new trains.”

A new fleet of Orange and Red Line cars are being built for the MBTA and the first vehicles are expected to enter service on the Orange Line later this year.

One reply on “Glitch boosted numbers on MBTA dashboard”

  1. the automated system removed that gap in calculating the dashboard’s reliability metric
    If you do something like this, you gotta footnote your data so people know.

    Above and beyond that, is the MBTA’s “goal” to have one train in every ten be 44 minutes late? That’s what a 90% goal on a “dashboard” means, and I suggest data weighting. 5 minutes and 44 minutes are not the same thing.

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