THE MBTA reported on Wednesday that all of the slow zones on the Green Line extension have been removed – good news that was surprisingly buried in a MassDOT press release about repairs being completed early on the Squires Bridge in Somerville.

The T has taken a lot of heat for 3 mile-per-hour slow zones on roughly a mile of track on the Green Line extension, which is less than a year old. T officials blamed the slow zones on track rails that were too close together, a defect discovered during inspections on September 13 and 14.

To remedy the problem, crews working in the early morning hours widened the rails where the tracks were too narrow and repaired rail ties in the areas where widening took place.  No rails were replaced.

T officials said they are still working to identify what caused the narrowing of the tracks in the first place.

Phillip Eng, the T’s general manager, told the transit authority’s board of directors late last month that the Green Line extension rails passed inspections when the line opened in 2022 and in subsequent inspections. He said it was unusual for tracks to narrow during use; usually, he said, tracks widen from use.

“It is not typical, but I wouldn’t say it’s impossible,” he told the board last month. “I need to find out more about how this came about.”

One of his top aides, Douglas Connett, the T’s new chief of infrastructure, said at the same board meeting that he believed the original work laying the Green Line extension tracks didn’t meet construction standards, meaning it was installed improperly.

The removal of the slow zones was announced in a Massachusetts Department of Transportation press release reporting that repairs to the Squires Bridge were completed in 25 days instead of the 42 originally planned.

The Squires Bridge carries traffic from Route 28/McGrath Highway over the Union Square branch of the Green Line extension, which required the line to be shut down during the bridge work. That allowed T repair crews to repair the track on that stretch of the line, while repairs to the still operating branch to Tufts had to be done in the early morning hours.

The MassDOT press release said the work on the Squires Bridge was wrapped up on Tuesday, which allowed the MBTA to run a test train under the bridge Wednesday morning and resume service after the test train encountered no problems.

“In keeping with our commitment last month to expedite track repair work during the Squires Bridge project, the MBTA has removed all of the Green Line speed restrictions on both the Union Station branch and the Medford/Tufts Station branch,” the MassDOT press release quoted Eng as saying. “Green Line trains today are traveling at regular line speeds on both branches.”

An MBTA spokeswoman did not respond when asked why the news about elimination of slow zones on the Green Line extension was contained in a MassDOT press release on the Squires Bridge repairs. The news about the elimination of the slow zones was first reported by State House News Service.