The Maine Turnpike Authority voted Thursday to widen a portion of the highway that runs from Exit 44 in Scarborough to just north of Exit 48 in Portland.
It would be the first phase of a two-phase project to increase the capacity of the turnpike as it carries traffic through the western portions of South Portland and Portland.
The second phase of the project would add a third lane in each direction from Exit 48 north to either Exit 52, the spur to Route 1 in Falmouth, or Exit 53, serving West Falmouth.
A spokesperson from the Turnpike Authority said that the first phase is estimated to cost between $140 million and $160 million. There is no cost estimate for phase two yet.
The Thursday vote followed an assessment by Turnpike Authority consultants of alternatives to widening, such as public transit, and whether those could handle the increase in traffic in the region. The consultants concluded that adding the third lane would be cost effective, could be funded, and built relatively quickly.
At the Turnpike Authority meeting, Executive Director Peter Mills recommended that, even with the widening, the Authority continue to look at proposals that would preserve the extra capacity.
Mills said the highway corridor from Biddeford to Portland, and possibly north to Gray, might host a successful bus service. "It's got to prove itself out. It's got to have goals.” Mills said. But, he went on, “the preliminary indications, from the study that we've just been through, are it should work."
Updated September 7, 2018 10:07 a.m. with updated cost estimates.