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 updates
Overnight closures on A1, A421 and Black Cat roundabout
As we continue with our work to upgrade Black Cat roundabout, the next step will be to install safety barriers, continue clearing the site of obstacles and carry out maintenance on CCTV cameras. These works will ensure that traffic can continue to use the A1, A421 and the Black Cat roundabout safely during construction.
The work will take place over three nights:
Thursday 25 April (1 night), 9pm to 5am
A421 westbound, Black Cat roundabout to Renhold
All traffic will divert via A1 southbound, A603 at Sandy then via Moggerhanger and rejoin the A421 at Cardington.
Bedford Road between Roxton Garden Centre and Black Cat roundabout
All traffic will divert via Roxton Road, Staploe Road, Bushmead Road to Eaton Socon and then south on the Great North Road (B1428) to Wyboston.
Friday 26 April (1 night), 9pm to 5am
A421 Eastbound, Renhold to Black Cat roundabout
Eastbound and local traffic heading to A1 southbound will use the A603 at Cardington then via Moggerhanger to Sandy and rejoin A1 southbound.
A1 Northbound Black Cat roundabout to Wyboston
A1 Northbound traffic will travel southbound on the A1 and follow the diversion via the A505, A1198 and A428 to rejoin the A1 at Wyboston.
Saturday 27 April (1 night), 9pm to 5am
A1 Northbound, Sandy to Black Cat roundabout
A1 Northbound traffic will use the A603 at Sandy then via Moggerhanger and rejoin the A421 at Cardington.
Overnight closures of A1198 Ermine Street South (Caxton Gibbet)
We will be closing A1198 Ermine Street South between Caxton Gibbet roundabout and the Stay Inn Hotel (CB23 3PB) overnight from Monday 29 April to Friday 3 May, 9pm - 5am.
The closure is to allow us to create a safe working environment so our operatives can carry out vegetation clearance.
Diversion route
From Caxton Gibbet roundabout, traffic will be diverted along the A428 westbound towards St Ives Road (B1040).
From the A1198 St Ives Road, traffic will be diverted along the B1040 and turn left onto the A428 eastbound and travel towards Caxton Gibbet roundabout.
During the road closures, local access to residential properties will be maintained.
A428 overnight closures
Before we can begin working on the new junction and slip roads at Cambridge Road in mid-May, we need to install a 40mph speed restriction, roadworks signs, safety barriers, narrow lanes, speed cameras and CCTV on the A428.
For safety reasons the works will be carried out under overnight closures at the following locations:
- Wyboston roundabout to Cambridge Road roundabout - Thursday 9 – Friday 10 May, 8pm – 5am.
- Cambridge Road roundabout to Caxton Gibbet roundabout - Monday 13 – Wednesday 15 May, 8pm – 5am.
Once complete, the narrow lanes will be in place until spring 2025 and will allow additional space at the side of the road to provide a safer working environment for our workforce to upgrade the junction at Cambridge Road.
Diversion route
Westbound traffic will use the A1198 north then A14 west, at Brampton Hut A1 south then at Wyboston west on A428. Eastbound traffic will use the same route in reverse.
New layout on Black Cat roundabout
There has been a switch of the layout on the Black Cat roundabout, and the A421 Westbound (Towards Bedford/MK). These changes are essential to facilitate the construction of the scheme without closing any part of the road permanently, therefore trying to reduce ongoing disruption.
We have since added lane lines for traffic to follow. The inside lane for All Routes, predominately for A421 West and Roxton. The outside lane for A1N Only, continues around the roundabout. If you find yourself in the wrong lane, please continue around the roundabout, rather than move in front of vehicles heading toward the A421 West (Bedford/MK).
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.
The junction is extremely complex to manage due to the many points of entry and exit and the multiple lanes available, this is exacerbated as we are making a change to a layout which customers have become used to over several years. We need to allow a period for customers to become familiar with the new layout and for them to adjust to the new arrangement.
However, we are constantly working on other possible measures or layout adjustments which may need to be implemented if the familiarity does not come. We do not want to make any situation potentially worse for our customers, whilst relying on driver behaviour to support the latest layout.
What you will see
- 40mph speed restriction - will start approximately 1.2 miles on the approach to the Black Cat roundabout
- Speed cameras will be in operation to enforce the 40mph speed restriction
- Narrow lanes on A421 on approach to A1 Black Cat
- Temporary road realignment markings
- Workspace safety barriers and roadwork signs
- Vegetation clearance
Vegetation clearance
We will be carrying out vegetation clearance along our roadside verges ready for the start of the construction works later this year. This activity at times may be noisy, and we’d like to apologise in advance for any disturbance caused.
Please remember:
- To plan your journey accordingly.
- Traffic approaching the closure location shortly it begins is likely to be subject to the diversion while the closure is put in place.
- We always try to stick to timings, however these closures may be amended due to poor weather or operational reasons.
- You can get real-time traffic information via www.trafficengland.com.
How do we plan diversions, road closures and speed limits?
We have monitored traffic volumes at 24 different locations in advance of construction and will continue to monitor it throughout the construction period. Click on some of the headings below to find out how we'll keep traffic moving during construction.
- We've carried out a ‘highest safe speed' assessment to work out the highest, safest speed you can travel through the roadworks.
- Our assessment found that a 40mph temporary speed limit is necessary to protect the road user and workforce for works to be carried out safely.
- The temporary speed limit means junctions can operate under normal capacity, resulting in a lower number of full road closures.
- The speed limit of 40mph means the temporary barriers and narrow lane systems are safer for all road users.
- We have planned construction so there are minimum road closures, diversions and road layout changes to reduce confusion.
- Road closures will be minimised as much as possible to only essential works, such as demolition works or major phasing changes.
- We will use static narrowed lanes and temporary alignments to maximise the construction work areas and keep the number of full closures as low as possible. For example, we will keep two lanes open on the A421 eastbound when we move into construction.
- At later stages in the construction we will use some of the newly constructed slip roads to keep the traffic moving: we will use slip roads and link roads to create a temporary ‘large gyratory’ at the Black Cat while the new A1 underpass is constructed.
- The A1 will be kept open as much as possible, although it is expected that A1 closures will be needed to allow the safe construction of parts of the new road. These may require a combination of weekday night closures, weekend night closures and full weekend closures.
- We have a commitment to you the road user to provide a safe and suitable diversion route around a closure.
- We will only use diversion routes that can take the type and volume of traffic that is being diverted.
- The diversion routes will stick to major A roads on our road network to minimise rat running through local villages and on local roads.
- We have to follow the diversions which are set out in the development consent order (which is like our planning permission).
- We aim to reduce disruption in your lives by managing the traffic with clear signage and advance warning.
- By standardising the way we do this, we can provide safer and more reliable journeys for you, resulting in familiarity along unfamiliar routes.
- All diversion routes are agreed with the relevant local authorities.
Managing traffic flow during construction
Our visualisation shows how we’ll keep the traffic moving while we build the new Black Cat junction.
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