MBTA’s General Manager Phil Eng had few answers to many questions surrounding track defects found on the brand-new Green Line Extension when he appeared before the agency’s board of directors.

A dramatic slowdown in service on the Green Line Extension to Medford, which opened for service just nine months ago, materialized last week.

Questioned by the MBTA’s Board of Directors Thursday, Eng said he could not explain why the rails had apparently narrowed. More than a dozen slow zones were imposed on the Medford and Union Square branches when it was discovered that the rail gauge or distance between the rails was too narrow — a narrowing that increases the risk of derailment for trains running at full speed.

“It certainly is unusual in terms of track to show a narrower condition,” Eng said at the Thursday meeting. “Obviously, as you're running trains, you would typically expect the gauge to widen.”

More than a dozen people eagerly gather around a green ribbon to cut at the opening ceremony.
Big names like then-Gov. Charlie Baker, Sens. Elizabeth Warren and Ed Markey, Rep. Katherine Clark, Somerville Mayor Katjana Ballantyne and Tufts mascot Jumbo the Elephant gathered at the Green Line’s Medford/Tufts station when it opened in December 2022.
Business Wire Courtesy of the MBTA

According to TransitMatters, which monitors T performance, trip lengths went from around 11 minutes between Tufts and Lechmere two weeks ago to around 16 minutes this week. Speeds have been reduced to as slow as three miles per hour in some sections.

MBTA spokesperson Joe Pesaturo says the speed restrictions on the Union Square branch will be eliminated by the time the branch reopens in two weeks, and that repairs to eliminate the speed restrictions on the Medford branch are continuing this week.

The MBTA continues to have significant problems with assessing the condition of its tracks. Recent reports found that Maintenance of Way workers, who have been responsible for checking for track defects, either didn’t understand their responsibilities or didn’t fulfill them. As a result, almost the entire system has had to be reinspected and the discovery of new and more widespread track defects is what has led to the persistent speed restrictions and slow zones which have plagued riders for the past year.

Eng said it appears the narrowed condition recently appeared, and that the GLX team is responsible for addressing the track condition and determining its cause.

“We need to investigate what took place between when the previous runs did not indicate any narrow gauge to the recent ones that resulted in the speed restrictions,” he said.

Robert Butler, who sits on the board of directors, asked Eng if there were any problems with the specifications for the track which resulted in them being too narrow. Eng suggested there might have been.

“I do need to look into that. I don’t want to without seeing the information myself, make too many assumptions,” he said.