Work on the Heysham to M6 Link Road will begin in the New Year after protesters failed at the final hurdle.
One last attempt by campaigners Transport Solutions for Lancaster and Morecambe (TSLM) to stop the road was thrown out by the Court of Appeal.
Lancashire County Council can now start to build the £124.5m road to link a remodelled Junction 34 of the M6 motorway with the Heysham bypass, and aim to have it open by June 2016.
The road will run through parts of Halton and Torrisholme, and will include new slip roads, a new bridge over the River Lune and a 600 space park and ride site.
County Councillor John Fillis, cabinet member for highways and transport, said: “We’ve always been confident of the case for the link road, which is widely supported by local people and businesses, and I couldn’t be more pleased that we can now get on with building it.
“Whilst I’m very satisfied at the strong judgement in our favour, I’m also extremely frustrated that objectors have cost the people of Lancashire an extra £2.6m by pursuing what amount to no more than delaying tactics.
David Gate from TSLM said the legal system had “failed the local community and common sense.”
“Our case against the road remains strong, persuasive and reasonable,” said Mr Gate.
“This failure of public policy has produced an expensive, destructive and ultimately useless new road.”
David Morris, MP for Morecambe and Lunesdale, said: “The road will be a much needed asset to the local community and will provide an economic boost.”