In a reversal, Gov. Maura Healey’s administration has announced that the Green Line Extension will actually not be shut down for six weeks in the middle of summer, delaying repairs on a deteriorating Somerville bridge until September.

The change comes as the Sumner Tunnel closure went into effect on Wednesday, wreaking havoc on traffic around the region.

The announcement also comes after a group of Somerville state representatives wrote to state officials about their concerns regarding the Green Line Extension shutdown.

Last week, the MBTA said Green Line train service between Lechmere and Union Square stations would be suspended for 42 days from July 18 to Aug. 28. This planned service disruption was because of repair work by MassDOT on the Route 28 Squires Bridge, which crosses over tracks near Union Square station.

But now, that repair work will be pushed until September.

“The Healey-Driscoll Administration is postponing construction on the Squire Bridge until September 2023,” Karissa Hand, a spokesperson for the governor, said in a statement on Wednesday.

“Green Line service will not be suspended between Union Square and Lechmere from July 18-August 28, 2023,” Hand added.

MassDOT crews inspected the bridge over the weekend, and determined it was safe to delay repairs until September “so that the closure does not occur at the same time as the Sumner Tunnel closure and to allow appropriate time to explore mitigation options and communicate with the public,” the governor’s spokesperson said.

“The administration is grateful for the feedback we received from local officials and community members and will maintain close communication as we work to reschedule the Squire Bridge construction,” Hand said.

On Monday, the Somerville state reps wrote a letter to MassDOT Secretary Gina Fiandaca, the MBTA board and MBTA GM Phillip Eng about the pending shutdown.

The state reps said they were concerned that the alternative travel bus options would not be enough during the six-week service disruption.

“Thank you to the Healey-Driscoll Administration for responding to our advocacy in support of transit equity for Union Square,” state Rep. Mike Connolly tweeted on Wednesday after the news broke about the change in plans. “I am hopeful this extra time will give MassDOT and the MBTA an opportunity to improve the plans for the Squires Bridge repairs.”

MassDOT needs to repair deteriorating steel on McGrath Highway’s Squires Bridge, which will ultimately impact the Green Line service in September.