M25 junction 23

Improving junction 23 of the M25 by increasing capacity.

Start date August 2019

End date October 2021

Cost £7.5 million

Latest updates

09 December 2021

Scheme now complete

We are pleased to announce that work at junction 23 is now complete.

The £7.5m upgrade at the junction, which connects the M25 with the A1(M) sees the widening of the southbound A1 entry slip road to provide a two-lane entry onto the southbound A1 which will ease congestion and improve safety.

The upgrade also sees a new footway for pedestrians from the BP service station to the existing footway.
As well as improving safety, the transformation has made the junction safer and easier for drivers and also includes an upgrade of the traffic signal timings to improve flow through the junction.

A new lane at the Bignells Corner exit from South Mimms services, with a widening of the M25 westbound exit slip road to accommodate an additional lane has made the layout more intuitive as drivers approach the junction. This has created a more free-flowing and safer network in the area around the junction, helping to accommodate local traffic and improving safety for users, including those using the junction to travel to and from the M25 and wider destinations in the UK.
11 March 2021

Bignells Corner update

Since the beginning of 2021, we have completed work to reinstate a new drainage channel, install new kerbs and resurface sections of the roundabout carriageway. We have also finished installing new utility channels and street lighting at Bignells Corner.

Current activities are being done whilst closing lane two on the inbound carriageway, and lane one on the outbound carriageway overnight.

Continued periods of cold and wet weather throughout January and February meant we were unable to carry out some of our planned resurfacing work of Bignells Corner.

To complete this work, we will be closing the road over seven nights starting from Monday 8 March (between 10pm and 5am). A clearly signed diversion will be in place via junction 22 of the M25 and the B556 to Bignells Corner.

If you would like to subscribe to our monthly newsletter, please contact JIP@CONNECTPLUSM25.CO.UK

Sign up for updates to this scheme page.
13 November 2020

Overall works over 80% complete

Works around the junction have recently seen the removal of the temporary safety barriers on the M25 anti-clockwise exit slip road returning to three narrow traffic lanes. This will help increase capacity when approaching the roundabout. Sheet piling works on the A1 southbound entry slip offside verge are now also complete.

Works at Bignells Corner have currently been suspended for the safety of the travelling public and our workforce, due to an increase in non-compliance with traffic management. Our teams are currently working to find the safest solution to completing the works within this area as efficiently as possible, and plan to continue works in this location starting in late November.

Our works over the coming month look to complete the widening works on the A1 southbound entry slip road, recommence our works at Bignells corner and prepare for planned resurfacing works around the junction.

If you could like to subscribe to our monthly newsletter please email us: JIP@CONNECTPLUSM25.CO.UK

Sign up for updates to this scheme webpage.
26 May 2020

Works at Bignells Corner gets under way

We’re bringing our planned works at Bignells Corner forward and will be carrying out some of these shifts between 8am and 5pm until June. To allow us to undertake these works safely, the full closure of the outbound dual carriageway to the junction 23 circulatory will be required. At least one traffic lane will be re-opened at the end of each shift. Lanes may remain closed outside of working hours for the safety of road users.

Traffic counts will be undertaken daily and should traffic levels start to increase towards normal levels, works will be reverted to overnight shifts.

If you could like to subscribe to our monthly newsletter please contact JIP@CONNECTPLUSM25.CO.UK

If you would like to be notified when we update this scheme webpage please sign up here.

Coronavirus (Covid-19)

Our current priority is to play our part in keeping the country safe, whilst supporting the movement of essential supplies, services and people who cannot work from home. We are following the government’s policy, which advises that construction activity should continue where it can be done safely. All our sites have strict safeguarding measures, in line with Public Health England guidance, to prevent the spread of Covid-19 and protect workers and the public.
12 May 2020
Work completed so far

Works completed or underway since the start of the scheme in August 2019.

A1 southbound nearside:
- Sheet piled retaining wall has been completed
- Drainage works have been completed
- Ductwork for new lighting has been installed
- Surface water channel has been completed
- Pavement works are currently underway
A1 southbound offside:

Vegetation clearance has been completed

Gyratory opposite M25 anti-clockwise exit slip road:
- Drainage has been completed
- Ductwork for signals has been completed
- Works are currently underway on new signage and landscaping
M25 anti-clockwise exit slip road:
- Sheet piled retaining wall and reinforced concrete capping beam have been completed
- Drainage has been completed
- Street lighting and traffic signal ducting has been completed
- Pavement construction is currently underway
Bignells Corner:
- Site clearance has been completed
- Temporary street lighting has been installed
- Earthworks for pavement on nearside and offside is currently underway

See more updates

Project information

Work will see widening of the A1 southbound merge slip road to provide a two-lane entry to the A1 south and a new footway for pedestrians from the BP service station to the existing footway adjacent to the roundabout.

The scheme incudes an upgrade to the traffic signal timings to improve traffic flow through the junction. There will be a new lane at the Bignells Corner exit from South Mimms services with widening of the M25 westbound exit slip road to accommodate an additional lane on the approach to the junction to reduce congestion.

The M25 junction 23 is controlled by traffic signals, and is where the M25, A1, A1(M) and A1081 meet. Junction 23 is operating over its design capacity, which leads to congestion, queuing traffic and journey delays during peak hours. The junction 23 scheme also provides for safety improvements within its design as well as a more free-ﬂowing network with reduced congestion and more reliable journey times.