Tunnel closures have halted Green Line and Orange Line service through Haymarket.

IN ANNOUNCING the shutdown of subway service running through the tunnels underneath the Government Center parking garage, the MBTA laid out ways for riders to get where they need to go but ultimately concluded the smart move may be not getting on the T at all.

“Because of expected delays as buses navigate downtown streets, the MBTA also encourages commuters directly impacted by the tunnel closures to consider working from home while diversions are in place, if they are able to do so,” the transit authority said.

The tunnel closures on the Orange and Green lines were prompted by the partial collapse on Saturday of the Government Center Garage, which is in the process of being demolished to make way for life sciences labs. Peter Monsini of South Easton died when a piece of heavy machinery he was operating fell several flights when the floor beneath him gave out.

The tunnel closures mean the Orange Line is cut into two parts, with the stops between North Station and Back Bay closed.  For the Green Line, stops between North Station and Government Center are shut down. The T launched shuttle bus service between North Station and Government Center, and suggested alternative routes for some travelers, but also advised that remaining at home may be the best alternative.

T officials said they expect the tunnels to be closed for several days as engineers examine the tunnels to determine whether they are safe.

If the tunnels remain closed this weekend, significant chunks of the MBTA could end up being offline unless scheduled repair work is canceled. MBTA General Manager Steve Poftak announced last week that the Blue Line would be closing between Government Center and Maverick Station for track replacement from April 2 until April 14.

The T is also planning to shut down the Red Line between Harvard and Alewife this coming weekend and the following weekend to make repairs.

Ari Ofsevit, a transit activist, tweeted out his concerns about what could happen if the tunnels underneath Government Center garage are not cleared for service soon. “If the Government Center garage isn’t remedied by this weekend, we basically won’t have a subway system,” he wrote.

Bruce Mohl oversees the production of content and edits reports, along with carrying out his own reporting with a particular focus on transportation, energy, and climate issues. He previously worked...