enlarge John Ewing/Staff Photographer

An arrow points motorists to a new Route 201 exit ramp that will allow southbound traffic to get back on I-295 below the construction without going through downtown Topsham.

enlarge John Ewing/Staff Photographer

A staging area off Interstate 295 in Richmond is busy with activity Thursday as workers prepare for the I-295 repaving project.

FOR MORE INFORMATION on the project, call (866) 319-9732 or go to www.mainedot.gov.

TOPSHAM — The clock on what transportation officials are calling Maine's biggest road-repair project in decades begins ticking at midnight Sunday.

That's when crews from Pike Industries Inc. will set up barricades, effectively shutting down 18 miles of southbound travel lanes on Interstate 295 between Gardiner and Topsham.

Pike Industries will then have until Aug. 30 to remove the top layer of concrete from the 36-year-old road, crush the bottom layer of concrete into a gravel-like substance and repave the road with more than 180,000 tons of blacktop.

The project is expected to affect thousands of commuters who use the interstate, as well as tourists visiting Maine at the height of the summer season.

"It's the Waldo-Hancock bridge of the road-building world for us," said Jim Hanley, spokesman for Pike Industries, referring to the new Penobscot Narrows Bridge in Prospect that opened in December 2006.

The concrete road, which opened in 1972, has deteriorated badly over the years. Rather than keeping one southbound lane open during the repair -- a process that might have stretched the project over three years -- the state Department of Transportation decided that finishing the job faster would be better, even if it meant closing the highway entirely.

"A project of this scope normally would have taken us three years," said Sterling Paul, the project's engineer. "We're going to do it in 10 weeks. It's going to be 10 weeks of craziness."

Incentives have been built into the $28.5 million contract that could pay Pike Industries up to $2 million if it finishes before the Aug. 30 deadline. Late penalties could also be imposed if the paving is delayed by lengthy periods of rain.

The work begins at 12:01 a.m. Monday in Gardiner when crews will erect barricades. Once the southbound lanes, entrances and exits have been blocked off, crews will arrive around 5 a.m. to begin removal of the top 3 inches of concrete from the existing highway.

By the middle of next week, another wave of construction crews will begin to crush the underlying concrete pavement. The road won't be paved until later.

Also on Monday morning, a new Route 201 exit ramp will open to allow southbound motorists to avoid downtown Topsham by getting on I-295 near the Topsham Fair Mall, before heading south to Freeport or Portland.

Route 201 cuts through the towns of Topsham, Bowdoin, Bowdoinham and Richmond, and is one of two alternate travel routes recommended by the state.

Brad Foley, director of safety for the MDOT, said the state plans to closely monitor Route 201 traffic, which is expected to increase from about 3,000 cars daily along that stretch to 13,000.

The MDOT has already installed signs, reflective road cones, a traffic light and mile markers with a mileage countdown to raise driver awareness.

The detour will add about 15 minutes to a commuter's trip, Foley estimated.

Bowdoinham Town Manager Kathy Durgin-Leighton said she has received so many inquiries about the project that she had a reminder about the start date posted on the town's Main Street message board.

Most of the town's residents commute to work outside Bowdoinham, she said.

"I would compare what we're going through to sitting on the edge of your seat. We're all just wondering what is going to happen," Durgin-Leighton said.

The other detour option for southbound motorists is the Maine Turnpike south from Augusta.

During construction, the Maine Turnpike Authority will offer free EZ passes to motorists affected by the project, but the passes must be returned by October.

Commuter Larry Niles, who currently travels daily from his home in Falmouth to his job in Augusta at the Family Planning Association of Maine, said the closure will be inconvenient and more costly for him.

Niles will still travel north on the interstate, but will be forced to take...