STEVE LeBLANCBOSTON (AP) â¿¿ Massachusetts has closed a $100 million deal that includes the purchase of nearly 40 miles of rail lines from CSX Transportation as part of a plan to build a commuter rail link from Boston to Fall River and New Bedford. Gov. Deval Patrick said Thursday that construction on the commuter rail will begin this summer with the rebuilding of three freight bridges in the New Bedford area. That work is expected to create 200 to 300 jobs and should be completed by early 2012, Patrick said. It's being funded with a $20 million federal grant and $1.7 million in state money. Under the deal, the state has acquired track running from Cotley Junction in Taunton to Fall River and New Bedford. The state now controls the tracks and will be able to run passenger trains once the South Coast line begins operation, officials said. It also includes the purchase of about 8 miles of track in the Allston-Brighton area of Boston. The deal is the latest in a series of steps needed to turn the estimated $1.4 billion rail project into a reality, Patrick said. Another big step should come this fall, when the Army Corps of Engineers is expected to make recommendations for their preferred path for the rail link, Patrick said. That recommendation had initially been expected earlier this year. Officials have long touted a rail link between Boston and the South Coast as a way to curb suburban sprawl, cut greenhouse gas emissions and revitalize the region's economy. Despite a series of false starts by past governors, Patrick said he's committed to seeing the project through. "We are going to deliver this project and all its economic benefits," he said. U.S. Sen. John Kerry said the state's congressional delegation is also committed to obtaining the federal dollars needed for construction of the rail link. The project will raise property values and lure employers to an area which has struggled with high unemployment, he said.