The Maine Department of Transportation is preparing to seek bids for a project that will make numerous changes along a 1.73-mile section of U.S. Route 1A in Hampden, including replacing the Grist Mill Bridge over Souadabscook Stream and adding a sidewalk to the west side of the road.

In two years, the runners, dogwalkers and other pedestrians of Hampden will have a new way to get around town: almost 2 miles of fresh sidewalk stretching along the west side of Route 1A from Western Avenue to Mountainview Drive.

That’s some of the good news about the upcoming changes, according to Town Manager Jim Chandler. The new sidewalk will connect with an existing sidewalk that already comes in from Bangor on U.S. Route 1A.

“It’s going to give the citizens of Hampden a continuous sidewalk,” he said. “There’s a huge advantage to that.”

Now for the bad news. Until the work is done, the project that’s being led and largely funded by the Maine Department of Transportation will create headaches for local drivers.

“You’re going to need a helicopter to get around Hampden,” Chandler has been telling residents, as a joke. Actually, he said, “It’s not going to be that bad,” but it will be “huge.”

Besides leaving a new sidewalk and a grassy esplanade along what’s now a narrow shoulder along 1A, the 1.73-mile project will also repave the road and upgrade its drainage. At the same time, the town will take advantage of the roadwork to make its own water and sewer upgrades.

More dramatically, the Maine DOT project will also replace the Grist Mill Bridge that now carries 1A over Souabadscook Stream.

The project, which went out to bid in late March, is scheduled to be mostly completed by the fall of 2020, though some final paving may happen in spring 2021, according to Rhobe Moulton, a senior project manager for Maine DOT.

It’s not clear how local drivers will be affected by the large project, as Maine DOT has not yet put together a plan for managing traffic, but detours could be required while the bridge is being replaced.

To minimize the disruptions for local families and school bus drivers, Maine DOT is requiring that the contractor wait until school lets out for the summer to start replacing the bridge, either this summer or in the summer of 2020, Moulton said. The replacement bridge would then have to be completed before the middle of the following November.

“We have told them we would prefer that be done in the summer months,” Chandler said.

When the bridge is going in, traffic may need to be detoured along Coldbrook Road and Western Avenue to U.S. Route 202, Chandler said.

Maine DOT will pay an estimated $5.9 million for the project, while Hampden voters have authorized up to $1.2 million to be spent on it. The town is responsible for providing 10 percent of the funding for the road repairs, but is paying on its own for the sewer and water upgrades, Chandler said.

It’s one of several state road projects planned for Hampden in the coming year. The agency plans to replace or improve several other bridges, including ones that carry Interstate 95 over Souadabscook Stream and Emerson Mills Road.

Maine DOT is planning to hold a meeting about those bridge projects at 6 p.m. on April 18 at the Hampden Municipal Building.