National Highways estimated the upgrade scheme will cut journey times by 10 minutes each trip

National Highways has given an update on the UK’s most expensive road project, the A428 Black Cat to Caxton Gibbet improvements. More than two years into construction, a spokesperson for National Highways has confirmed that the route is on track to open in spring 2027.

The £1 billion upgrade aims to deliver a new 10-mile dual carriageway linking the A1 and A421 Black Cat roundabout in Bedfordshire with the A428 Caxton Gibbet roundabout in Cambridgeshire. National Highways is redeveloping the Caxton Gibbet roundabout into a two-level junction.

This will link the new A421 dual carriageway with the A428 and A1198. Traffic on the new dual carriageway will move over the junction using a flyover bridge.

One recent milestone in the construction included work beginning to lower the A1 by eight metres at Black Cat junction. This is described by National Highways as “the most complex element of the scheme”.

In February, 11 beams were lifted into place for the new flyover at Caxton Gibbet. Once complete, the bridge will carry the A421 over the junction, aiming to allow traffic to flow more freely.

National Highways said that the steel structure is now in place for the new 250-metre viaduct over the River Great Ouse. The bridge-like structure aims to allow smooth travel across the river.