Mobile County will start work Wednesday on its second roundabout, which is expected to ease congestion at the intersection of Three Notch Road, Dawes Lane and the Dawes Lane Extension.

The $536,000 intersection project for the one-lane roundabout will take up to seven months to complete. Detours will be in place and motorists are asked to exercise caution in the area.

Mobile County was the first county in the state to receive federal money for construction of a roundabout under the High Risk Rural Road Program. It led to the construction of the roundabout at Grelot and Cody Roads, which was installed in 2010.

The county sought funding for the Three Notch and Dawes intersection to reduce the numbers of right angle crashes that have occurred there and will receive federal assistance from the Federal Highway Safety Administration.

The roundabout can eliminate right angle and head-on crashes because traffic will flow in one direction.

At the same time, the configuration forces a reduction in speed and eliminates the delays associated with stop-and-start traffic that occurs at a signalized intersection.

According to stats from the Federal Highway Administration of the U.S. Department of Transportation, roundabouts have delivered a 67 to 80 percent reduction in fatalities or incapacitating injuries and a 35 percent reduction in all crashes.