RICHMOND — The state will get a $10.8 million federal grant to help replace the deteriorated 80-year-old Richmond-Dresden bridge, two of Maine’s U.S. legislators said Monday.

Building a new bridge to replace the narrow swing bridge, which takes traffic across the Kennebec River on Route 197, is expected to cost about $25 million.

State Department of Transportation officials said work could start in 2013 and the new bridge could be ready for traffic in 2015.

The $10.8 million grant, combined with other federal money, is expected to pay for about half the cost of the project, with the state providing the other half.

Sen. Susan Collins, a Republican, and Rep. Chellie Pingree, a Democrat, announced the federal bridge funding in separate releases Monday. The competitive grant to Maine comes through the Transportation Investment Generating Economic Recovery, or TIGER, program.

Collins, who toured the bridge Dec. 2, said in a statement that she was alarmed by the deteriorated condition of the Richmond-Dresden bridge.

“It is an understatement to say that the time has come to replace and modernize this 80-year-old bridge, which is a critically important transportation link in this area,” Collins said.

Pingree said the bridge also is important to allow Coast Guard cutters and other large vessels to pass underneath on the Kennebec River.

The 1,239-foot bridge, also called the Maine Kennebec Bridge, was built in 1931. About 3,200 vehicles use it each day, according to state data.

State transportation officials looked into repairing the bridge or replacing it with a new low-level swing-span bridge, but rejected both options as too expensive.

Officials now plan to replace it with an upriver span high enough to allow boats to pass beneath. Exactly how high will be determined in consultation with the Coast Guard to make sure it is high enough to allow vessels used to break up ice in the river each spring to pass underneath.

Keith Edwards — 621-5647

kedwards@centralmaine.com