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
Please remember
Closures can change at short notice. For up to date information, check our daily closures page.
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
Cycle and footway closure, Caxton Gibbet
As part of our work, we need to close the cycleway and footway (73/17) just north of the existing roundabout.
A new route will open in Spring 2027.
Diversion
We'll put a diversion in place from Monday 8 July 2024.
The diversion will run 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
See a map of the cycleway and footway diversion.
Give us your feedback
Visit our A428 Black Cat to Caxton Gibbet improvements feedback tool to have your say. This tool includes an interactive map. You can click on a location to make a specific comment, or give us your 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
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.
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