Opening timetable revealed for new A421 and Black Cat road improvements

Most of the long-awaited A421 improvement scheme will open in spring 2027, with the final section at Black Cat junction following later in the summer.

Drivers will be able to use most of the new A421 dual carriageway between Bedfordshire and Cambridgeshire from spring 2027, as National Highways prepares to open the majority of its major road improvement scheme.

The first phase will include the new 10-mile dual carriageway linking Black Cat junction with Caxton Gibbet, alongside several key junction upgrades designed to improve safety and reduce congestion.

Among the improvements opening next spring will be the new A421 flyover at Black Cat junction, dual carriageway access at the new Cambridge Road junction, and the fully upgraded Caxton Gibbet junction.

The final stage of the project – the new A1 underpass at Black Cat junction – is now expected to open in mid-summer 2027.

National Highways says the underpass is the most technically challenging part of the scheme. During construction, engineers uncovered a larger-than-expected number of previously unrecorded underground utility services, including water, gas and telecommunications infrastructure, which had to be safely relocated before work could continue.

The organisation said moving these essential services, much of which is carried out by utility companies, has delayed completion of the final phase.

By opening the scheme in stages, drivers will benefit sooner from improved journeys between Milton Keynes, Bedford, St Neots and Cambridge, while work continues on the remaining section.

Until the A1 underpass is complete, traffic on the A1 will continue to use the existing Black Cat roundabout. National Highways says it will confirm exact opening dates for both phases in early 2027.