The proposed bridge will be 409 metres long

Plans for the Barnstaple western bypass include a 2.7-kilometre (1.7-mile) stretch of new road and a 409-metre (447-yard) long bridge across the River Taw, to be known as the Downstream Bridge.

The proposals were put forward by Devon County Council to try to alleviate traffic congestion in the town.

Environmentalists argued the bridge would attract more vehicles into the area and clog up the roads even more.

Friends of the Earth (FoE) campaigners battled to stop the project by making a legal challenge at the Appeal Court last summer.

Barnstaple is notorious for its traffic congestion which is harming the economy of the town and the environment Brian Greenslade, Devon County Council

They said the scheme would disturb large numbers of seabirds on the Taw and Torridge Estuary, along with the habitat of endangered otters.

But the appeal was dismissed by three Appeal Court judges.

They then appealed to the House of Lords against a decision by the transport secretary to back the scheme following a public inquiry.

That has now been rejected and the council says work to build the bridge could start in October.

However, FoE plans to campaign against government funding of the project and is considering taking the matter to the European courts.

Devon County Council executive chairman Brian Greenslade welcomed the decision of the Lords.

"Barnstaple is notorious for its traffic congestion which is harming the economy of the town and the environment," he said.

"The building of the western bypass will allow the through traffic which currently has to come through Barnstaple to go around the town and relieve congestion in the town centre."