A reconstruction project began Tuesday that will close the heavily traveled Route 1 viaduct in Bath for nearly eight months.

Drivers going north and south will be diverted to the ground-level Leeman Highway and Commercial Street to get around the construction site as the Maine Department of Transportation rebuilds the viaduct at an estimated cost of $12 million. The work will be done around the clock, seven days a week, and will cause traffic delays.

More than 18,000 vehicles travel daily over the viaduct, which allows traffic to avoid Bath’s downtown and the Bath Iron Works shipyard. However, the city’s downtown and businesses will remain accessible for those who want to go there.

“Access to historic downtown Bath will be maintained and all businesses will be open throughout the project,” the MDOT says on its website.

When the project is complete, MDOT says the viaduct will have:

• Improved sidewalks, crosswalks, signage, lighting and guardrails

• Improved appearance. The city of Bath will make landscaping improvements as the project is completed.

• A design less conducive to pigeons roosting under the viaduct.

• Drainage improvements, with separation of storm water runoff from the city sewer system.

The viaduct will reopen on Memorial Day 2017 at the earliest, according to MDOT.