Costs of junction improvements to allow extra train services have spiralled to £600m.

MPs and rail campaigners have been calling for extra tracks at Ely North junction, whose layout causes a major bottleneck on the region’s rail network.

Lines from all four points of the compass meet at Queen Adelaide, north of the city.

Proposals which began as a £35m junction upgrade a decade ago now include improvements to crossings, bridges and Ely station.

Network Rail says extra measures are needed because the original scheme will not permit more frequent trains to run between King’s Lynn and London or the east - west routes.

Chancellor Rishi Sunak pledged to spend more than £600bn on rail, roads, affordable housing, broadband and research over the five-year Parliament in last week’s budget.

There are hopes Ely North could be included. But South West Norfolk MP Elizabeth Truss, who has campaigned for improvements since she was elected in 2010, said “The project first started at £35m now they’re saying it’s £600m. There’s too much gold plating on the project and we want to get back to basics.”

North West Norfolk MP James Wild said: “We sat down with the rail minister last month and he gets the need for it. He wants to get Network Rail, the MPs and the train operating companies in a room and work out what’s actually needed.”

A Network Rail spokesman said: “We are absolutely committed to improving the railway for our passengers and to drive and support economic growth. The scheme originally put forward was to double the junction at Ely but this wouldn’t release the additional services the rail users and local communities need.

“A far wider range of interventions is required including layout changes at Ely station, improvements to bridges, power upgrades and improvements to level crossings, in order to fully meet demands. We will put this forward to the Department for Transport in the Spring.”

There are three level crossings in less than a mile of road, where the lines divide at Queen Adelaide.

Around 5,000 vehicles a day use the road through the village. But housing developments are expected to increase traffic to an estimated 8,000 a day.

Officials say a new bridge or underpass will be needed, as more frequent trains will increase the amount of times the crossings are closed, causing gridlock otherwise.