A DESPERATELY-NEEDED £17m bypass is finally set to be built in Merseyside – four decades after it was first proposed.

The Switch Island to Thornton bypass, aiming to relieve congestion in residential streets in Netherton and Thornton, got the green light yesterday as part of a £1.5bn package for roads.

Transport Secretary Philip Hammond listed the 4.2km project among eight top priorities the Department for Transport (DfT) was “committed” to building over the next four years.

But work will not start for at least two years because of a £600m backlog of existing local transport schemes still to be completed.

Sefton Council has also been told to slim down the cost of the bypass in order to deliver a “best and final offer”, a process identical to the cautious go-ahead for the Mersey Gateway project at Widnes.

However, an aide to Mr Hammond told the Daily Post: “This scheme is good value for money and we want it to go ahead. We are committed to it.” A funding package will be revealed in January.

The new road would connect the Switch Island M57 and M58 interchange with the A565 to Crosby, relieving Green Lane and Lydiate Lane of thousands of cars and lorries daily.

Measures such as lower speed limits, cameras, traffic islands and mini-roundabouts are expected to be introduced in the surrounding streets.

The project has been under consideration for 40 years – and was given the green light under Labour earlier this year – before the coalition Government froze all local transport schemes.