Diversions, closures and speed restrictions

We're trying to minimise road closures and keep traffic flowing as much as possible while the improvements are carried out. Stay up to date with diversions, road closures and current restrictions on this page.

While it won't always be possible to completely avoid some short-term delays and congestion, we have looked at lots of different scenarios and outcomes to keep open as many lanes as we can. We are working closely with local authorities to keep traffic moving as much as possible during construction.

What you can expect to see:

The A1, A421 and A428 will mainly remain open for the duration of the works.

There will be occasional overnight closures and full weekend closures, when we'll need to connect the new and existing roads, build bridges, and unload sizeable items of equipment or materials.

We're committed to being a good neighbour - so we're working hard with our contractors to plan and phase the construction, to really minimise impacts to all road users and the local community.

Current closures

A421 weekend closure - June 2025

We are building the new embankments close to the A421 carriageway.

To work safely, the A421 will be closed in both directions between Renhold Interchange and Black Cat roundabout from 9pm Friday 27 to 5am Monday 30 June 2025. 

Diversion

We will divert traffic via the A603 at Cardington to A1 northbound at Sandy to the Black Cat roundabout.

See A421 diversion route map

Anglian Water is connecting new water mains near to the A1 northbound carriageway.

To work safely, the A1 northbound will be closed between Black Cat roundabout and Wyboston from 9pm Friday 4 to 5am Monday 7 July 2025.

Diversion

We will divert traffic off the A1 at Tempsford onto St Neots Road through Little Barford. Traffic will then head west on the A428 via St Neots and rejoin the A1 northbound at Wyboston.  

See A1 northbound diversion route map

We are making changes to the road layout at Black Cat roundabout, including the A1 southbound approach to the junction.

To work safely, the A1 southbound will be closed overnight between Wyboston and the Black Cat roundabout at the following times:

  • 9pm Tuesday 8 to 5am Wednesday 9 July 2025
  • 9pm Wednesday 9 to 5am Thursday 10 July 2025

Diversion

We will divert traffic off the A1 at Wyboston onto the A428 towards St Neots. Traffic will then head south on Barford Road before rejoining the A1 southbound at Tempsford.

See A1 southbound diversion route map

We're making changes to the road layout at Black Cat roundabout, including the A421 eastbound approach to the junction. 

To work safely, the A421 eastbound will be closed overnight between Renhold Interchange and Black Cat roundabout at the following times:

  • 9pm Tuesday 8 to 5am Wednesday 9 July 2025
  • 9pm Wednesday 9 to 5am Thursday 10 July 2025

Diversion 

We'll divert traffic off the A421 at Cardington onto the A603 towards Sandy, before taking the A1 northbound towards the Black Cat roundabout.

See A421 eastbound diversion route map

We're moving utilities, installing new drainage and kerbs on the A428 near Cambridge Road and at Eltisley.

To work safely, we'll close the A428 between Tithe Farm roundabout to Caxton Gibbet roundabout from 8pm Friday 11 to 6am Monday 14 July 2025.

Diversion

  • you'll be diverted along the A428 towards St Neots/A1
  • then continue north on A1 to Brampton Hut
  • return on A1 southbound to join A14 eastbound
  • leave the A14 at A1198 Ermine Street
  • follow diversion signs along A1198 to Caxton Gibbet roundabout.

A428 weekend closure diversion map.

We are sheet piling for the new bridge over the A1 northbound carriageway at Kelpie Marine.

Sheet piling is a method in bridge building where long, thin sheets of steel or other materials are driven into the ground to create a temporary or permanent wall that supports the soil and water during construction.

To work safely, the A1 northbound will be closed between Tempsford and the Black Cat roundabout from 6am Saturday 19 to 6am Monday 21 July 2025.

Diversion

We'll divert traffic off the A1 at Tempsford onto St Neots Road through Little Barford. Traffic will then head west on the A428 via St Neots and rejoin the A1 northbound at Wyboston. Traffic heading towards Bedford should use the A603 via Moggerhanger. 

See A1 northbound diversion route map

Please remember that closures can change at short notice. You can check the latest information on our daily closures page or find live travel information on our Traffic England site. Our travel alerts give details of live incidents on our network.

Give us your feedback

Use our A428 Black Cat to Caxton Gibbet improvements feedback tool to have your say.

This tool features an interactive map, allowing you to click on specific locations to leave targeted comments or provide general feedback.

ECHO is a one-way feedback tool, so if you'd like a response to your feedback you can email the project team at:info@a428.co.uk

Long term changes

Eltisley junction opens to traffic - from April 2025

As part of the construction of the new A421 dual carriageway between the Black Cat roundabout and Caxton Gibbet, 

We're making changes to to how drivers use the A428 at Eltisley:

  • we'll remove the B1040 north junction at St Ives Road
  • drivers will use two new roundabouts linked by a bridge crossing the new dual carriageway. 

From 14 April 2025, we'll direct traffic on the A428 onto the new junction at Eltisley. 

Following this we'll: 

  • remove the closed section of A428 carriageway
  • build a new connection linking Cambridge Road (Eltisley) and the new southern roundabout. 

We expect to reopen Cambridge Road (Eltisley) in summer 2025. 

Eltisley junction layout from April 2025.

As we build the new dual carriageway between the Black Cat roundabout and Caxton Gibbet, we're changing  the A428 and A1199. 

From June, we'll redirect traffic on the A428 onto a new stretch of road.

On this new section, if you're driving towards Cambridge you'll use the newly built northern roundabout.

Then you'll take the A1198 southbound exit towards the existing Caxton Gibbet roundabout.

From there, you can either continue on the A1198 or rejoin the A428 towards Cambridge.

If you're driving towards St Neots,  follow the same route in the opposite direction. 

Once we've finished the switch, we'll remove the old section of the A428 before building the new dual carriageway. 

Caxton Gibbet route map.

We're changing  the A428 at Cambridge Road near St Neots.

From June, we'll redirect traffic on the A428 onto a new stretch of road.

On this new section, if you're heading towards Caxton Gibbet, follow the new route through the northern roundabout.

Then cross the bridge and continue through the southern roundabout to rejoin the A428.

If you're driving towards St Neots, follow the same route in the opposite direction. 

Once we've finished the switch, we'll remove the old section of the A428 before building the new dual carriageway. 

Cambridge Road, St Neots route map.

In January 2024, we made a temporary switch to the road layout at the Black Cat roundabout as we began work to upgrade the junction. This temporary layout has allowed traffic to continue to pass through the roundabout smoothly - removing the need to close any part of the road permanently.

The current road layout will be in place until spring 2025.

Please be assured that we take your feedback extremely seriously and have been monitoring the area constantly since implementation. We monitor via live CCTV, as well as multiple daily visits to site at various times of the day, in daylight as well as in the dark.

View temporary road layout map

Cycle, pedestrian and horse rider route closure, Caxton Gibbet

As part of our work, we need to close the cycleway, pedestrian and horse rider route (73/17) just north of the existing roundabout.

While these works take place, cyclists, pedestrians, and horse riders will be directed along a diversion route, running eastward along the A1198 Ermine Street, avoiding our worksites and rejoining the road at Brockley Road.

We estimate the diversion will make journeys longer by:

  • 5 minutes for cyclists
  • 15 minutes for walkers

View diversion route map

An upgraded route will open to cyclists, pedestrians, and horse riders in spring 2027.

From 8 July 2025, we'll close the northern section of the roundabout

This will temporarily stop road users travelling south on the A1 from the A421.

If you want to travel southbound on the A1, you have two options:

  • continue north on the A1 to Wyboston, then loop back southbound.
  • exit the A421 at Cardington, take the A603 towards Sandy.

We'll install a concrete barrier on the roundabout to separate A1 southbound traffic from other routes. This will prevent lane changes on the roundabout and help keep traffic flowing safely.

The approach from the A1 northbound remains unchanged.

Black Cat roundabout layout map.

Planning diversions, traffic management and speed limits 

We've monitored traffic volumes at 24 different locations ahead of construction. We'll continue monitoring it throughout construction.

Highest safe speed

We've assessed that a 40mph temporary speed limit is necessary to protect road users and our workforce.

The temporary speed limit allows junctions to operate at their normal capacity. This means we'll need fewer full road closures.

Carriageway and slip road closures

We've planned our work to keep road closures, diversions and road layout changes to a minimum.

As far as possible, we'll only use closures for for essential works, like demolition or major phasing changes.

We'll use static narrowed lanes and temporary alignments to maximise working space. This will help us keep the number of full closures as low as possible. For example, we'll keep two lanes open on the A421 eastbound when we start construction.

Later in construction, we'll use some of the newly constructed slip roads to keep the traffic moving. We'll use slip roads and link roads to create a temporary ‘large gyratory’ at the Black Cat while we build the new A1 underpass.

How we choose diversion routes

We're committed to giving you safe and suitable diversions around closures. We'll only use diversion routes that can take the type and volume of traffic that's being diverted.

Diversion routes will stick to major A roads on our road network, minimising rat running on local roads. We'll agree diversion routes with the relevant local authorities.

We must follow the diversions set out in the development consent order (which is like our planning permission). 

We'll reduce disruption by managing traffic with clear signs and advance warning.

 

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