In just eight days, one of the most heavily traveled roads in Maine will be closed to traffic for more than seven months.

The Maine Department of Transportation will use the shutdown period to rebuild the Bath Route 1 Viaduct at an estimated cost of $12 million.

The two-lane elevated highway, which allows traffic to avoid Bath’s downtown and the Bath Iron Works shipyard, won’t reopen until Memorial Day 2017 at the earliest.

Construction work will go on around the clock seven days a week, but the state promises the disruption will be worth the wait. The new Viaduct has been designed to last 100 years.

“Those in the immediate area should expect noise, vibration, dust and truck traffic at any time. Work has been scheduled for a time of year when most have their windows closed, so that may help. We recognize this is unwelcome, but it is unavoidable,” the MDOT said in a mailing sent to local residents and businesses this fall.

“Working day and night shortens the total duration of the project dramatically. When it’s done, it won’t have to be repeated for many decades. So we ask for your patience and understanding,” the DOT statement concludes.

The closure will take effect Oct. 11, the day after Columbus Day.

Since 1958, the Route 1 Viaduct has carried vehicles over downtown Bath, past the giant cranes that tower over the BIW shipyard, and over the Central Maine and Quebec Maine Railway lines that run underneath the elevated road.

During construction, Route 1 traffic will be diverted to the ground-level Leeman Highway and Commercial Street to get around the project site.

The state is not trying to gloss over the impact of the project, admitting in statements on the project website that construction work will cause traffic delays. More than 18,000 vehicles travel over the Route 1 Viaduct daily, heading north over the Kennebec River to Woolwich and Wiscasset or south to destinations in the Brunswick area.

The state is also being careful to reassure business owners that the city’s downtown will be accessible. “Access to historic downtown Bath will be maintained and all businesses will be open throughout the project,” the MDOT says on its website.

Once the project is completed, the new highway’s highest point will be about 30 feet above the streets underneath it. The Viaduct will be a quarter-mile long and will run from High Street to the Sagadahoc Bridge on the Kennebec River.

During construction, the state is warning motorists to be aware of changing traffic patterns, signs and flaggers. Detour routes may vary and most of the detours will occur overnight between 7 p.m. and 6 a.m.

The state replaced the surface of the Viaduct in 2006 in hopes of extending the life of the structure for 10 years.

In late April of this year, the MDOT closed the Viaduct to perform work on the aging road’s guardrail a few weeks after an SUV crashed through a section and plummeted to the road below.

Reed & Reed Construction of Woolwich was awarded the contract to rebuild the Viaduct.

For updates on the project, go to MaineDot.gov.