A rider waits to climb on the MBTA green line at the Lechmere station March 21. (Photo: Marc Levy)

A delay in opening Medford Branch stations on the green line subway extension project through Somerville also means a four-week shutdown in trolley service on the just-opened Union Square branch, the MBTA said Friday.

Shuttle buses will replace trains between Government Center and Union Square stations in both directions from Aug. 22 to Sept. 18 after passenger service along the Union Square branch began just March 21. The dates almost match a shutdown of the orange line.

“This is madness,” said state Rep. Mike Connolly, who serves East Cambridge and East Somerville, in a comprehensive thread posted to social media. “How can we shut down the northern green line at the same time as the orange line? As we’ve been grappling with the pending orange line shutdown, I’ve been thinking about how East Somerville constituents might consider using the Union Square or Lechmere Green Line stops as an alternative way to get into Boston – but now, those options won’t be available.”

The Medford branch lines – East Somerville, Gilman Square, Magoun Square, Ball Square and finally, in Medford, College Avenue – were expected to open in late summer but now are expected in late November.

Behind the delay are “a number of contributing factors,” the Massachusetts Bay Transportation Authority said in a Friday press release. The start date has “been affected by the availability of safety and operational support crews that were previously prioritized for GLX, but are now reallocated to other MBTA construction work, including in the MBTA’s response to the Federal Transit Administration’s Safety Management Inspection directives.”

That refers to the subway system as a whole being shifted to a less-frequent Saturday schedule after federal inspectors said June 15 that the agency had too few people to operate on weekday levels.

The slowing of green line station openings and shuttle buses along the Union Square branch allow for “final-phase construction elements” on the extension and to the East Cambridge Viaduct, but “this diversion in service is also necessary to allow for continued repairs to the Government Center Garage,” where several floors collapsed March 26, killing a construction worker.

Since then, the most notorious failing of the system involved an orange line train bursting into flames on a bridge over water. On Wednesday, the MBTA said it plans a 30-day shutdown of the entire line from Aug. 19 to Sept. 18 to “accelerate major track and maintenance work.” The orange line goes to Somerville’s Assembly Square and has stops in Charlestown at Sullivan Square that serves Somerville and at Community College that serves Cambridge’s North Point neighborhood.

The work will “allow for an overall rehabilitated system that is safe and efficient for employees and neighboring communities,” said Jamey Tesler, the state’s secretary of transportation.

The problems and the fixes affecting riders outraged officials.

“What an epic failure of leadership. How can we even be a transit leader, a climate leader or a world-class city without a functioning transit system?” Cambridge vice mayor Alanna Mallon asked via social media.

Even Assistant Speaker of the U.S. House of Representatives Katherine Clark, a Melrose resident, commented Wednesday on the orange line news: “It is outrageous that years of underinvestment have left the MBTA with this decision of last resort just to ensure basic safety for riders. This service disruption will upend the lives of those who have already been hit hardest by the pandemic and its economic fallout. There needs to be a clear, comprehensive plan for the tens of thousands of people who rely on the orange line every single day and significant investment in our public transit system to finally take it into the 21st century.”

Despite the steady pace of bad news, state transit officials were focused Friday on the benefits of the latest disappointment for riders on the green line.

“The temporary diversion of Union Branch riders onto shuttle buses will provide contractors with around-the-clock access to the tracks and overhead wire system, enabling them to safely and quickly complete work deemed critical to the opening of the new Medford Branch,” the MBTA said.