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.

Diversions, closures and speed restrictions

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.
Traffic officer carrying a cone next to a van

Current updates

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. 

Upcoming works: Central reservation works

We will be reconstructing the existing central reservation into a running lane – this means we will keep two lanes open on the A421 eastbound when we move into construction.

This work will start from Monday 30 October 2023 until mid-January 2024 and our working hours will be 7:30am to 5pm. Your journey will not be affected, as we will be maintaining two lanes of traffic in both directions on the A421.

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.

Highest safe speed
  • 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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