State set to endorse 3 railway projects

State environmental officials plan to announce today that they have endorsed a revised list of transit pledges to offset increased air pollution from the Big Dig, setting in motion three major projects that could change the way people travel in the Boston area.

Officials from the state Department of Environmental Protection say the new list will double Boston's air quality gains, reduce more air pollution for each dollar spent, and encourage transit-friendly residential and commercial development.

The revised list, which was proposed by transportation officials in May, continues to be hotly debated and is the focus of a lawsuit filed by environmental advocates, with a second suit being launched.

The environmental agency's endorsement allows the Massachusetts Bay Transportation Authority to extend Green Line service to both West Medford and to Union Square in Somerville by 2014; to add stations and improve service on the Fairmount commuter rail line by 2011; and to add at least 1,000 parking spaces at commuter rail stations in the Boston area by 2011.

''These three projects, and particularly the Fairmount and Green Line projects, are enormously powerful transit commitments," said Douglas I. Foy, secretary of Commonwealth development. ''We will do our best to get them on the ground immediately."

The Department of Environmental Protection will hold public hearings next month and receive comments through Jan. 3 before making its decision official.

The decision by the Department of Environmental Protection is a blow to supporters of three projects left off the revised list, including restoration of trolley service on the Arborway line in Jamaica Plain and a subway connection between the T's Red and Blue lines near Charles/MGH station.

''We feel like transit riders in the urban core are being sacrificed in a cynical maneuver by the Commonwealth to walk away from longstanding commitments," said Phil Warburg, president of the Conservation Law Foundation, which received the original transit commitments from the state in 1990 after the group threatened to file a lawsuit to stop the $14.6 billion Big Dig highway project.

''We have no more confidence that these substitute measures will be implemented than the measures that the Commonwealth has abandoned," he added.

The Conservation Law Foundation sued the state in March, arguing that the state is not living up to its full transit promises. Last week, Partners HealthCare and its affiliate Massachusetts General Hospital said they plan to file a separate lawsuit against the state over the Red-Blue connector.

Foy said both the Arborway line and the Red-Blue connector will remain on the state's priority list of potential transit projects, saying the latter ''clearly has merit."

''The state will proceed full speed, and the lawsuits will do what the lawsuits will do," said Foy, who helped negotiate the original list when he was president of the Conservation Law Foundation.

The Department of Environmental Protection's 66-page report on the transit commitments, obtained by the Globe, includes a provision that gives the MBTA and the state an additional three years' leeway to finish the projects.

State officials say they are committed to spending $770 million on the projects and said they are assured the projects will receive state and federal funding. In March, Governor Mitt Romney introduced a 20-year, $31 billion transportation plan under which the state takes over the construction costs of major MBTA projects.

The Department of Environmental Protection did not approve one of the transit projects announced in May: the doubling of service on the Worcester-Boston commuter rail line. But it is still on a long list of possible future projects, Foy said.

The largest of the planned projects would be the Green Line branches to Union Square in Somerville and to West Medford, which would be similar to the Green Line branches in Boston, Brookline, and Newton. At an estimated $559 million, it would be one of the largest MBTA expansions since the mid-1980s.

The state also plans to spend nearly $100 million to build four stations -- at Newmarket, Four Corners, Talbot Avenue, and Blue Hill Avenue -- along the long-neglected Fairmount Line. For decades, commuter trains have rumbled through Hyde Park, Mattapan, and Dorchester, but a limited number of station stops made it difficult for residents of those neighborhoods to ride the line. T officials project that ridership would jump from 2,800 per day now to about 7,300 daily once the four stations are built.

Foy said the expanded Fairmount service could turn an hourlong bus ride from Hyde Park and Dorchester into downtown Boston into a 12- to 15-minute trip.

''Simply put, this is a much better package than what was envisioned a decade and a half ago," Transportation Secretary John Cogliano said in a press release. ''Times and technology change, and these revised commitments reflect that fact. This proposal enhances transit options in the Boston metro area, while adhering to strict air quality standards."

The Department of Environmental Protection report says, for instance, that the Red-Blue connector would cost nearly $264 million to build and would remove 16 kilograms per day of hydrocarbons from the air and 190 kilograms of carbon monoxide.

By comparison, the report says, the Green Line extension to West Medford and Union Square has a construction cost of $459 million, but would result in a far larger air pollution reduction of 83 kilograms per day of hydrocarbons and 1,016 kilograms per day of carbon monoxide.

All told, the report said, the revised list of projects would reduce hydrocarbons by 100 kilograms a day and carbon monoxide by about 1,200 kilograms a day, compared with about 45 kilograms of hydrocarbons and 543 kilograms of carbon monoxide for the three projects left off the list.

Environmental Protection Commissioner Robert W. Golledge Jr. said the list should not be viewed as final.

He said that if the state continues to face delays in the projects, new or revised projects could be required.