Motorists are being advised “to be prepared” as the road layout at Bedfordshire’s Black Cat roundabout will change next week.  National Highways is moving to the next stage of construction on the A428 Black Cat to Caxton Gibbet Improvements.  

From Tuesday 8 July 2025, the northern section of the Black Cat roundabout will be closed to allow for construction of the new A421 flyover bridge and lowering of the A1 carriageway.  

As part of National Highways scheme, the roundabout will be transformed into a three-tier junction. Through a new purpose-built cutting, A1 traffic will flow freely below ground, while A421 traffic will travel over the junction on a new flyover. Local roads will remain at ground level, making it easy to connect between routes. 

Once complete, journeys at peak times are expected to be cut by 10 minutes, saving businesses and road users an hour and a half over a working week. 

Paul Salmon, National Highways Senior Project Manager, said: 

“We’re making good progress across the scheme and remain on track to open the new 10-mile dual carriageway and junction upgrades in spring 2027.  

“With this road layout change, our construction work at Black Cat roundabout will step up as we begin the complex process of lowering the A1 carriageway and building the new A421 flyover bridge. We understand that any change to this busy junction impacts drivers, so we’re asking people to be prepared and follow the signage as they approach the roundabout next week.” 

Changes at Black Cat roundabout from Tuesday 8 July 2025: 

• A421 eastbound traffic will only be able to use the A1 northbound exit. Drivers wishing to travel southbound are to continue north on the A1 to Wyboston then loop back southbound, or exit the A421 at Cardington and take the A603 towards Sandy.  
• The A1 southbound approach will be reduced to three lanes. A concrete barrier will be installed to separate traffic on the A1 southbound with other routes to ensure vehicles stay in their lane while using the roundabout.  
• There will be no change to traffic on the A1 northbound. 

The traffic lights on the A1 southbound approach will also be removed when the northern section of the roundabout closes. This will reduce congestion and improve the flow of traffic through the roundabout. 

The northern section of the roundabout will remain closed until spring 2027, when the entire scheme is expected to be complete. 

In the coming months, further changes to the road layout will be introduced as new links open. Later this summer, the A421 eastbound to A1 free-flow link will open, allowing for seamless movement between the two roads. 

(Pic: National Highways)