Members of Dorset County Council's cabinet gave their backing to the scheme which is designed to ease congestion around Weymouth.

The 3.75km (2.3m) stretch of carriageway is aimed at tackling traffic jams along the A354 from Weymouth to Dorchester and the A353.

Compulsory purchase orders will now be made for the required land.

The council aims to start work on the road in January 2008, with the project due to be completed in 2011.

Protesters have claimed the road will have a major adverse impact on the environment.