MARIETTA — Workers have started the process of building a new, $11.2 million bridge at Canton Road over Cobb Parkway, a project that is expected to take more than two years to complete.

Work on the project, which is being paid for with state and federal funds, started Aug. 8 and is expected to continue until March 2014, said Mark McKinnon, spokesman for the Georgia Department of Transportation.

The GDOT evaluates its bridges every year, and the current Canton Road bridge has reached the point that it needed to be replaced, he said.

“You don’t want them to get to a level where they’re not safe,” McKinnon said. “We try to stay ahead of the curve.”

McKinnon said the road and railroad bridges have been worn down by industrial truck traffic over the years.

The bridges have also caused problems on Cobb Parkway, also known as U.S. Highway 41, because it narrows the road and leaves only 13 feet for trucks to squeeze under, said Dan McDuff, deputy director for Cobb DOT.

“You can see it’s been hit many, many times,” he said. “The new bridge will be very good from a safety standpoint.”

The new bridge will give at least 17 feet of clearance, McDuff said.

The old bridges, which were built in 1938, are “past the point” of needing replacement, he said.

“Part of the problem is the bridges are structurally deficient,” he said. “They need to be replaced because they are in really bad shape.”

The bridges recently received a deficiency rating of 15.5 out of 100, McDuff said.

“That doesn’t mean it’s unsafe, but it really means it’s beyond repair,” he said.

The project will also mean a new Georgia Northeastern Railroad bridge and a redesign of Industrial Park Drive at Cobb Parkway, McKinnon said.

“They’ll make that intersection a little easier to navigate,” he said.

Workers for C.W. Matthews of Marietta, who was awarded the contract for the project, are currently clearing brush to prepare for the larger work, McKinnon said.

“I imagine they’ll be pretty heavy into construction by early next year,” he said.

And once construction picks up, that means traffic could slow down. McKinnon said drivers on Canton Road will be most affected, but there could be delays on Cobb Parkway as well.

“They don’t like to work directly over moving traffic,” McKinnon said.

The new bridge will be “nicer and newer,” though Canton Road will not be widened for the project. But McKinnon said the wait will be worth it.

“Folks, just be patient with us through the construction phase,” he asked. “I think they will be pleased with the final product.”