COMMUTERS TO BE PUT IN A JAM

Comm. Ave. project to affect all modes of travel

Drivers, train riders and straphangers could face nearly three weeks of hell on wheels beginning tomorrow as the state launches an $82 million replacement of the Commonwealth Avenue Bridge — with dire warnings of traffic jams on the Mass Pike and Green Line shutdowns.

“This is going to be disruptive and it’s going to be painful,” said Chris Dempsey, director of Transportation for Massachusetts, a coalition of organizations warning commuters of the project’s potential to worsen commutes.

The massive project is slated to launch tomorrow night at 9 p.m., and run into the early morning of Aug. 14, as crews begin work replacing the concrete and steal beams that carry Commonwealth Avenue over Interstate 90.

The project is set to be done in two phases, first this summer and then again next year, snarling car, train, trolley, bicycle and pedestrian traffic.

“I can’t think of (a project) in recent memory that is going to be touching so many different modes” of transportation, Dempsey said. “You have trolleys and you have buses and people crossing the river on the B.U. bridge. It really does touch everything.”

Worse still, the daunting undertaking will send ripple effects across the city, not seen since the Big Dig, including:

• Lane closures on the Pike come Friday night with the highway cut to just two lanes both ways from Allston to as far away as the Seaport. I-90 will be sliced to just one lane on weekday and weekend nights. Jonathan Gulliver, MassDOT’s acting highway administrator, said drivers could face up to an additional 40-minute delay at times.

“I will tell you,” Gulliver said at an early July press conference, “there is not a single person in the department that can recall a project that will have this widespread of impact.”

• Commonwealth Avenue will shut down between Kenmore Square and Packard’s Corner — the intersection of Commonwealth and Brighton avenues — to all cars, except for T buses, replacement shuttles and emergency vehicles, from Thursday night through Aug. 14; and

• The Green Line’s B branch will be replaced by shuttle buses from Babcock Street to Blandford Street throughout construction. On a typical weekday, 27,000 people ride the B branch, according to MBTA spokesman Joe Pesaturo, and the transit agency is readying 32 buses during peak hours to help move them along.

“There will be very significant disruptions affecting all modes of transportation ... but certainly the most disrupted will be the Pike driver,” said Mary Connaughton, a former member of the nowdefunct Massachusetts Turnpike Authority Board who’s now at the Pioneer Institute. “If there’s ever a time to buy a commuter rail pass, it’s now.”

With train tracks running under the bridge, even commuter rail won’t be spared. During this weekend and next, the Framingham/ Worcester train line will end at Brighton’s Boston Landing station, where riders can take shuttle buses to the Green Line’s D branch to make it downtown.

The only exception will be for service for Boston Red Sox games this Saturday and Sunday, as well Aug. 5 and Aug. 6. The T will run service from Boston Landing to the Yawkey Station three hours before the start of each game; the train will head outbound 30 minutes after the last out.

The rest of the time it will be every commuter for themselves.