The MBTA's Red Line — its busiest — sees just 72 percent of its trains arrive within a minute of schedule and accounts for $1.5 billion of the T's $7.3 billion state-of-good-repair backlog.
That information was presented to the T's fiscal control board Monday as part of a line-by-line look at the system aimed at giving the recently created board a clear picture of the state of T operations.
The report also showed that the line, which accounts for 22 percent of all T ridership, is regularly over capacity at major stops during the morning commute -- including at Broadway, South Station, Central Square and Harvard.
The presentation came on the same day that Red Line commuters waited through lengthy delays attributed to weekend work to replace some of the track that runs on the Longfellow Bridge.
"For the first 48 hours or so, we impose a 10 mile per hour speed restriction on the train operations," T General Manager Frank DePaola said during Monday's meeting. "So that going through there, if there's any shifting or small settlement of the ties into the ballast, there's no issues related to the train operation."
That speed limit caused severe delays in both directions during the Monday morning commute.
DePaola said he was hopeful that trains would be able to move at normal speeds by the Tuesday morning, but said that would depend on an assessment made by T officials after the Monday evening rush. He said that after similar work a week before, trains had been able to resume normal operations by Tuesday morning.
"If everything looks good we should be able to lift the speed restriction this evening," DePaola said.