Study to explore extension routes for Green Line

The MBTA took the first steps yesterday to extend the Green Line from Lechmere to West Medford, a $375 million expansion of the transit system that the state promised as a condition for undertaking the Big Dig.

A $391,000 study to be conducted by the firm Vanasse Hangen Brustlin of Watertown will spell out the possible routes and station stops of the 4.2-mile extension through Somerville, approved by the board of the Massachusetts Bay Transportation Authority. The study should be finished this year.

Somerville is more densely populated than Cambridge or Brookline yet has no light rail service, only one Red Line stop at Davis Square, buses, and commuter trains that pass through but don't stop, said Wig Zamore, a member of the Somerville Transit Equity Partnership.

The extension of the Green Line will go either alongside the Lowell commuter rail tracks to Washington Street, School Street, Lowell Street, Tufts University in Medford, and finally West Medford at Route 60; or along the Fitchburg commuter rail tracks to Union Square, and under a new tunnel under Prospect Hill to School Street.

Though the Green Line extension is among the state's legal obligations to expand the transit system as part of a 1990 pact giving the go-ahead to build the Big Dig, there are no firm funding plans for the project. Only the cost of the study is in the $2.5 billion, five-year capital spending plan the board approved yesterday.

While the Green Line extension is widely supported in Somerville, the T board got an earful yesterday about another expensive project that several Roxbury residents said they didn't want: the $760 million tunnel linking the current Silver Line bus service with Boylston Station and then South Station.

The Silver Line bus service can't replace the elevated Orange Line that ran down Washington Street until 1987, said Robert Terrell, a member of the Washington Street Corridor Coalition. The T should invest in turning the bus service into a light rail service like the Green Line, he said.

Instead, T planners have proposed connecting the bus service from Dudley Square to another line, expected to open later this year, that goes from South Station through the South Boston Waterfront and ultimately to Logan Airport. The connection would be made through a tunnel from Washington Street to Boylston Station, and then under Essex Street to South Station.

City Councilor Chuck Turner said the two projects -- the existing Silver Line and the waterfront portion of the Silver Line -- should be "uncoupled," because getting light rail service is more important than getting to the waterfront or to Logan for his constituents.

In other action yesterday, the T board approved a $1.2 billion budget request for 2005 that now goes to the state Legislature, and $238 million for independent contractors to operate The Ride, despite withering criticism from several users who testified yesterday that the paratransit service is often late and unreliable. In addition, the membership of the new 24-member Rider Oversight Committee was announced.

The committee, which the T agreed to form to hear customer grievances after the fare hike in January, consists of eight regular riders of subway or commuter rail, and representatives from advocacy groups.

Anthony Flint can be reached at flint@globe.com.