SALEM — The state is moving forward with millions of dollars in construction contracts for the Interstate 93 widening project.

“We’re going to do a lot of work in the next three years,” said Project Manager Peter Stamnas of New Hampshire Department of Transportation.

Stamnas presented selectmen with a progress report at their May 21 meeting.

The projects will widen 20 miles of I-93 and modernize five exits, including Exits 2 and 3. Construction crews will work on 43 bridges, including 19 on the “red list” and build 21 new spans. In addition to five miles of noise-barrier walls, three new park-and-rides will be created.

Mainline priority contracts to create three lanes in each direction from Exit 3 south are expected to be completed by 2016. Stamas estimated the cost at $342 million. About $209 million is under contract or complete, he said.

Capacity improvement projects along the corridor will start in 2015 and be done by 2020.

The projects are in the state 10-year plan. Recent funding from the Legislature and the decision to issue $115 million in new GARVEE bonds made it possible to move forward.

Active construction includes a $37 million project at the Exit 5 interchange, a $12 million contract for work on the Exit 3 southbound bridges over Routes 111 and 111A, and ongoing work at Exit 1 costing about $32 million.

Exit 1 should be completed by 2013, Stamnas said.

Upcoming work centers on Exits 2 and 3.

A $40 million contract was bid this month to widen 1.5 miles of the highway, replace two “red list” bridges and widen an eight-lane section of Pelham Road between Stiles and policy. A temporary bridge will be used and entry points for the southbound ramps will be reversed during construction and should be complete in 2015.

The switch is being done to minimize disruptions to commuters and keep traffic flowing through the work area, Stamnas said.

“I think Exit 2 is going to be a challenge, there’s no doubt about that,” Stamnas said.

Exit 3 work consists of two contracts. A $42 million contract will bid in July to reconstruct three miles of southbound lanes, shift 1.25 miles of Route 111 north with the bypassed portion ending in a cul-de-sac at Castleton, and reconstruct the southbound onramp by 2016.

A second contract for $37 million will reconstruct two miles of northbound lanes and ramps, relocate a half mile of Route 111A west, stopping at the intersection of Route 111 near the existing northbound off ramp, and complete Exit 3 work. That contract is expected to bid in September 2013, and work should be finished in 2016.

Overall, Stamnas said he was pleased with how work is progressing.

“There’s a lot going on out here,” Stamnas said. “Things are changing daily.”