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NEW BEDFORD – Lost amid last week’s outcries about rising cost projections for South Coast Rail and the possibility of a new route through Middleboro, a state legislator said, was a proposal for widening a section of I-93 that could affect virtually all commuters south of Boston and create a public-private partnership on an interstate.



“I’ve been waiting for someone to say: ‘The (state) secretary of transportation just proposed a significant expansion of the Southeast Expressway,’” state Rep. Bill Straus, a Mattapoisett Democrat who chairs the legislature’s Joint Transportation Committee, said to The Standard- Times Editorial Board on Friday.



Straus was referring to MassDOT’s presentation June 27 to the MBTA Fiscal Management and Control Board. The presentation updated the board on progress — and new alternatives — for the long-awaited, highly debated South Coast Rail connection.



The headlines from the presentation were that costs for South Coast Rail through Stoughton could reach $3.4 billion, and as a result Mass-DOT and state legislators are considering whether to study a new route through Middleboro, via Taunton.



But also notable is that a potential benefit of a Middleboro route, according to the presentation, could be widening much of the I-93 section known as the Southeast Expressway, which stretches from the Braintree split at Route 3 to South Boston.



The expressway passes the Savin Hill MBTA station in Dorchester. Previous studies of a potential Middleboro route for South Coast Rail have cited a “pinch point” of congestion at Savin Hill, where the singletracked, Old Colony commuter rail line would limit MBTA service to SouthCoast.



Straus said last week though that an additional right-of-way corridor in the Dorchester area, identified in the past few months, could allow for double- tracking the commuter rail and expanding capacity.



MassDOT suggested last week that I-93 could be widened from eight lanes to 10, at the same time as commuter rail was expanded. The widened I-93 could include four lanes northbound, four southbound and two “managed lanes” in the middle.



Straus described the managed lanes as, “reversible hot lanes,” with tolls.



Commuters could choose whether to pay tolls to take the middle lanes, the direction of which would change according to rush hours. A private company that would help widen the interstate would collect revenue from the tolls, Straus said.



“Addressing (the) Savin Hill pinch point also lays groundwork for a public-private partnership project to address congestion on Route 3/Southeast Expressway,” MassDOT’s presentation states.



Part of the Southeast Expressway already uses a so-called “zipper lane,” but its use means one side of the interstate has fewer lanes during certain hours. Straus said the expansion would keep at least four lanes in each direction at all times.



“We would go from five lanes of flowing rush hour traffic to six, and always have four in the opposite direction,” he said.



Adding another commuter rail track at Savin Hill would push those tracks below ground, along with the two Braintree tracks on the T’s red line, according to a basic crosssection provided in MassDOT’s presentation.



The shallow tunnel for the Braintree and commuter rail tracks would be below the southbound lanes of I-93, meaning the expansion projects could occur at the same time and with the same digs, so to speak.



Straus said the idea remains “purely conceptual” — but could have big impacts.



“It benefits everyone who drives from the south, up to and including from Quincy and Braintree,” Straus said.



Mike Lawrence may be contacted at mlawrence@s-t.com.

