Trains on the Framingham-Worcester commuter rail line this year have performed worse than trains on every other commuter line, with only 78 percent arriving on time.

For the month of November, on-time performance for trains on the line was 57 percent, compared to 69 percent for trains across the entire system.

Trains are considered late if they arrive more than five minutes after their scheduled arrival time.

"Historically the Framingham-Worcester line has performed the worst and continues to perform well below the overall system," said Scott Farmelant, a spokesman for the Massachusetts Bay Commuter Railroad Co. MBCR manages the commuter rail system for the Massachusetts Bay Transportation Authority.

CSX, the corporation that owns the tracks on which commuter trains travel between Worcester and Boston, spent almost a year replacing 33,000 rail ties on the line. The maintenance work was scheduled to be done at night, when commuter trains don't travel. Still, the work seems to have backed up commuter trains during peak hours.

CSX spokesman Robert Sullivan said the track work was done at night so it would have the least effect on commuters.