Riders are being redirected to shuttle buses, adding time and uncertainty to daily routines. Haley Serene, who relies on the MBTA to get to and from school, said the disruption has made it difficult to find the quickest route to class, with her commute taking up to an additional half-hour.

"Every other day, there's a shuttle bus right here. Now, there's a shuttle bus right there. It's just a lot of confusion," Serene said.

Micael Moreno, who travels from Brighton to UMass Boston, reported similar delays. "It adds like, 20 to 30 more minutes," Moreno said. While frustrated, Moreno acknowledged that the timing could be worse. "At least climate isn't that crazy right now," he said, referring to the work happening now rather than during the winter.

The disruption is also being felt beyond the Green Line. Mac Carvalho, owner and CEO of My Authentic Colors, recorded cellphone video Saturday evening showing what he described as unusually crowded conditions on the Orange Line near Boston's Jamaica Plain neighborhood.

"It was just strange to me that going off the Orange Line, it was that crowded, and I don't even think my video even captured how crowded it was," Carvalho said. He shared the video to warn other commuters about possible packed trains. "If you're someone who's like me, who doesn't love crowds, who feels like being packed in like sardines is a lot and you can't handle it, just as a heads up, like, 'This is what's happening, maybe seek alternate routes,'" he said.

Michael Nevin, who was affected by the disruption, questioned why more of the construction could not take place on weekends. "It makes more sense to do it on the weekends, when people aren't relying on it to get to work, but it's going to happen at some point," Nevin conceded.

Others are taking a more understanding approach. Candy Schwartz, a regular MBTA commuter, said she doesn't mind the shuttles. "There's a ton of work that needs to be done on the Green Line, on my Green Line, and they're trying to do it as best as they can without disrupting life," Schwartz said.

The MBTA is advising passengers to allow extra time for their journeys and anticipate delays of at least 25 minutes while shuttle buses replace portions of regular train service. The signal upgrades are part of ongoing efforts to improve reliability on the aging Green Line, which serves tens of thousands of riders daily.

The shutdown comes as the MBTA continues to grapple with infrastructure needs across its system. For riders like Serene and Moreno, the weeklong disruption is a temporary but frustrating hurdle, while others like Schwartz see it as a necessary step toward a better transit network.