Overnight Closures Announced on £1m-a-Day A421 Upgrade

National Highways has confirmed a fresh series of overnight closures as work continues on its major A421/A428 improvement scheme, a project reported to be costing around £1M per day.

The A421 westbound between the Black Cat junction and Renhold Interchange in Bedfordshire will be closed from 21:00 on Friday until 05:00 on Monday, 23 February. The closure will allow contractors to install ground-strengthening columns designed to stabilise embankments and supporting structures.

A signed diversion will direct drivers south via the A1, then along the A603 towards Bedford, before rejoining the A421 westbound at the Cardington Interchange.

Further overnight closures are planned for the A421 eastbound between Renhold Interchange and Black Cat junction from Monday, 23 February to Saturday, 28 February, operating nightly between 21:00 and 05:00. Diversions will be in place during these periods.

Major dual carriageway scheme

The works form part of a wider project to construct a new 10-mile dual carriageway linking the Black Cat roundabout in Bedfordshire with the Caxton Gibbet roundabout in Cambridgeshire. The scheme is intended to ease congestion along the busy A428 corridor and improve journey reliability across the region.

In January, a 100-tonne crane was used to lift beams into position for a new 200m viaduct spanning the River Great Ouse and Little Barford Road, with much of the operation carried out overnight under floodlights.

The scheme passed its halfway point last year and remains on track to open to traffic in spring 2027.