The MBTA has announced an unprecedented move to shut down an entire rapid transit line so they can make badly needed repairs to tracks, signals and power systems. The Orange Line closure begins Aug. 19.

Gov. Charlie Baker says the work that can be done during the 30-day closure would require five years if it were done just during overnight hours and on weekends, which traditionally has been the MBTA's practice. During the extensive overhaul, up to 200 buses will be deployed to transport passengers along the route. They will also be encouraged to take commuter rail and work at home, if possible.

Everyone agrees the shutdown will be greatly disruptive for the approximately 100,000 riders who depend on the Orange Line daily, but not all public transit advocates agree the temporary closure is a good thing. Some are concerned about the environmental impact of more buses and cars on the roads. Others worry the replacement shuttle buses won't be sufficient at transporting all of the line's regular passengers.

Staci Rubin, vice president of Environmental Justice at the Conservation Law Foundation, thinks the shutdown is a bad idea, stating it will add to Boston’s air pollution and congestion problems.

“Replacing fully electric subway cars with pollution-emitting buses is a huge problem … we're adding diesel emissions, which are exacerbating air quality ... and we're contributing to our congestion problem in Greater Boston," she said. "So we're really doing the opposite of what we should be doing at a time when we're trying to just get people to choose the T over their car.”

Rubin also said the 30-day closure is "unacceptable."

"It's awful that the MBTA has gotten to this point where they have to shut down an entire line just to maintain our tracks and infrastructure," she said.

The advocacy organization Transit Matters issued a statement complaining about the suddenness of the announcement: “The short notice of this announcement shows a lack of respect for riders. The quality of the T’s communications to riders throughout this effort, as well as the quality of its mitigation efforts, will be major tests for the agency.”

The organization also has concerns about the shuttle bus alternative.

“We are concerned that replacement shuttle buses have not functioned well during past diversions. Too often they were stuck in traffic, hopelessly delayed, and woefully insufficient to replace rail transit service," the statement read.

Stacy Thompson, executive director of the Livable Streets Alliance, agrees the 30-day shutdown will speed along repairs, but she too is concerned about the bus shuttles. Not the need for designated bus lanes to help them avoid traffic, butwhat I think might be more important is making sure that there's enough space for those shuttles to line up for people to wait if it's hot out or if it's raining. Is there cover provided? Is there a place to sit for older adults? These are practical needs.”

And Thompson says coordinating the 200 buses involved in the shuttle operation is a huge task that will require cooperation of not only Boston officials, but every municipality served by the Orange Line from Oak Grove to Jamaica Plain.

Thompson recognizes the 30-day shutdown is a big gamble.

“I’m going to remain optimistic and hopeful that they're taking a chance because they believe they can do it," Thompson said. "And I would encourage the public to also be hopeful about this move right now … I haven't seen another transit agency in the country take action like this. They've been put in a terrible position, but they're also taking on a Herculean feat. And I really hope it pays off. A lot is at stake.”

Produced with assistance from the Public Media Journalists Association Editor Corps funded by the Corporation for Public Broadcasting, a private corporation funded by the American people.