The consultancy was recognised at the International Road Federation's Global Road Achievement Awards for environmental mitigation on the A30 Bodmin to Indian Queens link.
The company worked with the Highways Agency and Alfred McAlpine on the scheme, which involved building 11.5km of dual carriageway with two junctions between the Indian Queens and Bodmin bypasses.
The route design was chosen to avoid Goss Moor, a special area of conservation crossed by the original road. Habitat was expanded and regenerated to support species such as the endangered marsh fritillary butterfly.
The road surface of the previous route has been replaced with facilities for walkers, cyclists and horse-riders. More than 6.5km of hedgerow has been added to mitigate noise.
Scott Wilson had to incorporate measures to minimise risk of flooding from the Fal and Camel rivers and ensure that groundwater flow was not diverted or accelerated because of the road.
The project also took local archaeological sites into account. The significant remains of a Bronze Age roundhouse were discovered during the construction of the road. Despite this the project was completed on time and on budget.
Scott Wilson highways director Paul Bracegirdle concluded: "This is a much-needed road that brings many improvements to the people of Cornwall."