Diversions planned for A1 Black Cat roundabout

The works will eventually create an A421 flyover bridge at Black Cat

Motorists are being warned to prepare for diversions and closures on a busy A1 roundabout as part of a £1bn road scheme.

National Highways said construction work on the route between the Black Cat roundabout in Bedfordshire and Caxton Gibbet in Cambridgeshire would "step up" on Tuesday.

The northern section of the roundabout will be closed so a new A421 flyover bridge can be built, and the A1 carriageway can be lowered.

Paul Salmon, senior project manager at National Highways, said: "We're asking people to be prepared and follow the signage as they approach the roundabout."

Mr Salmon said the 10-mile (16km) dual carriageway scheme was making "good progress" and on track to be open in spring 2027.

"We understand that any change to this busy junction impacts drivers," he said.

What is changing?

From Tuesday, drivers heading eastbound on the A421 towards Black Cat will only be able to take the A1 northbound exit.

Those heading south will be diverted via Wyboston, or will have to exit the A421 at Cardington and take the A603 towards Sandy.

The A1 southbound approach will also have a reduced number of lanes, with a concrete barrier to separate traffic from other routes.

There is no change to traffic heading along the A1 northbound.

Later this summer, a link between the A421 eastbound and A1 will open.

National Highways said the scheme, when finished, will cut peak-time journeys by 10 minutes.

It gave further information about next week's diversions and closures on its website.