The Framingham-Worcester line is the only commuter rail line operated by CSX. It is heavily traveled by freight trains, which can impede service on commuter trains. CSX controls dispatching for the entire line from Selkirk, N.Y.

The line stretches from Union Station in Worcester to South Station in Boston, with 15 stops in between.

Delays are the result of many factors, Mr. Farmelant said. He said wet leaves sometimes stick to railroad tracks and make them slippery, causing trains to slow down. But he attributed most delays this year to the extensive track work.

"The big issue with the fall was the massive tie replacement project that CSX undertook," he said. "Obviously this is important work that needs to be accomplished to keep the system in good order. They were doing overnight work that was supposed to be done before the morning commute, but it was impacting the morning commute," he said, especially between Labor Day and mid-October.

"Their intention was to minimize impact, but they created greater impact."

MBTA spokesman Joseph P. Pesaturo said on-time performance on the entire commuter rail system is the lowest it has been in years and called the figures discouraging, but said the MBTA is working with the MBCR to improve performance.

"One of the most challenging lines for us is the Framingham-Worcester line," he said.

The MBTA last week launched an e-mail and text message alert system that notifies commuters of delays on subway and commuter trains. The pilot program will be limited to 3,000 people and will continue for about five weeks before the program is made available to all commuters. More than 2,400 people have signed up to receive alerts, Mr. Pesaturo said.

Contact Priyanka Dayal by e-mail at pdayal@telegram.com