A428 Upgrade

The A1, A421, and A428 around Black Cat roundabout (Bedfordshire) and Caxton Gibbet roundabout (Cambridgeshire) are well known for heavy traffic and frequent delays.

This scheme will provide a new 10-mile dual carriageway and upgrades to Black Cat and Caxton Gibbet junctions, meaning quicker, safer and more reliable journeys for thousands of road users every day.

The new dual carriageway will replace the only stretch of single carriageway between:

• the M1 near Milton Keynes
• the east coast ports of Harwich and Felixstowe

This will help give more access to jobs in Milton Keynes, Cambridge and everywhere in between.

Once complete, journeys at peak times are expected to be cut by 10 minutes. This will save businesses and road users an hour and a half in travel time over a working week.

This is the route of the new A421 dual carriageway:

Planning diversions, traffic management and speed limits 

What you can expect to see

The A1, A421, and A428 will mostly stay open while work is carried out.

There may be some overnight and full weekend closures from time to time, needed for important tasks like:

• connecting new and existing roads
• building bridges 
• delivering large pieces of equipment or materials.

Highest safe speed through roadworks

A temporary speed limit of 40mph is needed to keep both road users and our workers safe.

This reduced speed limit helps junctions function as usual, which avoids closing roads as often.