BOSTON - Huge parts of the Green Line closed starting Monday, replaced by yellow Yankee shuttle buses riding through the city.

At the same time, along the exposed outdoor track along the B and E lines, crews were seen repairing and replacing track.

The green line closure is the early phase of the T's ambitious year-long plan to eliminate all slow zones along the entire system.

While the T did announce the diversion, which temporarily closes from North Station to Kenmore, Babcock Street, and Heath Street, many riders seemed utterly confused when they had to switch to shuttle buses Monday.

"Every week they have a new thing to close the stations. Now I am late for work," one woman exclaimed. 

"It's been a little rough," another added.

While navigating the shuttle buses can be confusing, people form MBTA watchdog agencies say the short yet painful diversions are actually a good sign.

"Generally speaking, this is not as catastrophic as it could be," said Stacy Thompson of LivableStreets Alliance. 

Thompson referenced the T's successful closure of parts of the Red Line recently which eliminated nine slow zones. 

"What we saw with the recent Red Line shutdown is that under the leadership of the new general manager, the T can actually fix things," she said.

Thompson said she feels like new leadership under General Manager Phillip Eng is slowly starting to return confidence in the MBTA.

"People who ride the system consistently have seen that it is getting better, that things are moving a little more smoothly. It's easier to get information," she said.

Plus, short yet efficient closures are a better alternative to a monthlong disruption like the Orange Line shutdown, she said.

"I would say that Phil Eng is using a scalpel instead of a sledgehammer," Thompson explained. 

"So, under his leadership, they are doing small sections of track at a time. Maybe it's a 3 day or 5 day or 10 day shutdown, really focusing, making sure the work is done well, and then you see immediate improvements."