Silver Line expansion to Chelsea planned

Governor Deval Patrick is expected to announce Wednesday morning that the MBTA Silver Line will be extended to East Boston and Chelsea, with a prospective opening date in late 2016.

The plan to expand the bus rapid transit line, mulled in transportation planning circles for years, is meant to connect the burgeoning Seaport District with Chelsea and East Boston, communities historically underserved by public transit.

Patrick’s announcement, which he is expected to make during a speech in Chelsea, comes as he continues to outline plans to spend money for transportation investments earmarked by state legislators earlier this year.

The new stretch of the Silver Line, which could carry as many as 9,000 passengers per day, is expected to cost $82.5 million, according to Patrick’s office. Of that sum, $20 million will be spent to relocate the Chelsea commuter rail station from 6th Street to a site two blocks away on Everett Avenue, which will allow the station to accommodate both trains and Silver Line buses.

“Bringing Silver Line service to Chelsea will provide an even more convenient and cost-effective route for its residents and neighbors to connect with the vibrant opportunity growing in the Seaport District and the City of Boston,” said Richard A. Davey, the state’s transportation secretary.

Patrick’s office estimates that the Silver Line extension would deliver commuters from the Seaport District to Chelsea in 15 to 19 minutes — a considerable improvement on the current public transit options. The 111 bus, which runs between Chelsea and Haymarket Station, is overcrowded and can take more than an hour.

The extension has been under community review for months, and has been lauded by some transportation advocates who view bus rapid transit as an improvement over regular bus service without the high costs of building a new subway line.

“This extension of the Silver Line will have an enormously beneficial effect on Chelsea,” said Marc Draisen, executive director of the Metropolitan Area Planning Council .

The Silver Line route in South Boston will remain the same as it continues on to Airport Station, skipping over the airport terminals. Then, the bus will travel along a bypass road that is currently open to taxis, trucks, and commercial vehicles, crossing the Chelsea Street Bridge before entering a newly constructed busway.