M23 junctions 8 to 10: smart motorway

Upgrading the 11 mile (18km) stretch of the M23 near Gatwick Airport, between junction 8 near Merstham and junction 10 at Copthorne, to an all-lane running smart motorway.

Region:  South East
Start date:  2017-18
Cost:  ¬£164 million
Status:  CURRENT
Type:  Major Scheme
End date:  2019-20
Programme:  Smart motorways

Have your say

We've introduced a new engagement tool where you can give your views on the project. Please click on the map below to add your comments about specific parts of the route.

Preview image of interactive map for what you would like to see improved along the M23 between Junction 8 and 10

Progress report

The consultation for the implementation of Variable Mandatory Speed limits between junctions 8 and 10, and the permanent 50mph speed limit on the westbound carriageway of the Gatwick Spur from the M23 junction 9 to 9a, was undertaken between 11 December 2017 and 15 January 2018. The summary of comments received and our responses can be found in the consultation report.

We can now announce the formal commencement of the scheme with our delivery partner, Kier.

We're regularly communicating with Surrey and West Sussex County Council and working closely with Gatwick Airport to issue joint communications when major work is taking place. The Smart Motorways Project can also be found on the Gatwick Airport App and web page.

Early environmental works are now completed. These have included vegetation and tree clearing along the verge. The clearance was undertaken to accommodate new retaining walls, environmental (noise) barriers, gantries and emergency areas as part of the scheme. All gantries are now in place, and technology is planned to be installed in the new year. Sound barriers are in situ with the exception of two areas where we are still undertaking works.

We are currently in the process of moving from the verge areas into the central reservation where we will be relaying drainage, installing the comms for the gantries and constructing a new central barrier.

What's next?

Starting at the end of February there will be a series of 56-hour weekend closures on the M23 between junction 8 Merstham and junction 10 Copthorne.

The works will begin on Friday 28 February and continue for the next four weekends. Full weekend closures will take place from 9pm on Friday and the M23 will reopen at 5am on Monday.

You can find out more information below - or you can view our weekend closure leaflet, and our map of the scheme.

  • Friday 28 February until Monday 2 March: Northbound junctions 10-8
  • Friday 6 March until Monday 9 March: Southbound junctions 8-10
  • Friday 13 March until Monday 16 March: Northbound junctions 10-8
  • Friday 20 March until Monday 23 March: Southbound junctions 8-10

The last weekend in March is a split weekend with a northbound closure from Friday night to Saturday night and a southbound closure the rest of the weekend:

  • 9pm Friday 27 March to 1am Sunday 29 March: Northbound junctions 10-8 (28 hours)
  • 1am Sunday 29 March to 5am Monday 30 March: Southbound junctions 8-10 (28 hours)

All closures will be subject to change and are weather dependent.

A fully signed diversion route will be in place to aid motorists with their journeys.

For more information contact 0300 123 5000, check this web page for regular updates or contact Carolyne Ferguson for more information.


Date Event
2016 ‚Äď March 2018 Design works
July 2018 Start of advanced works
September 2018 Start of main works
July 2019 Switch to central reservation
Spring 2020 Completion of main works

Community news

Over the next two years we'll be looking to help and support local community projects, along with our two chosen charities, Kent Air Ambulance and Neuro-Kinex Kids in Crawley, as well as supporting local schools and colleges with STEM work and apprentice/careers advice. We recently undertook a project for a local school to clear land so the children can plant in the spring and grow a sensory garden for the pupils to enjoy.

You can request to be placed on the weekly M23 junction 8 to 10 update regarding the scheme. To sign up for this email: M23J8_10smart@highwaysengland.co.uk

Why we need this scheme

The M23 is a crucial part of the UK strategic road network connecting Crawley and Gatwick Airport to the M25 motorway, routes into London and the rest of the UK. This stretch of the M23 is heavily used by traffic travelling to and from Gatwick Airport and between Brighton and London, especially during UK holiday periods. As a result safety, congestion and journey times are all key issues that need to be improved. As junction 9 of the M23 is the main access for traffic travelling to and from Gatwick Airport, this scheme is of particular local and national economic and political importance.


This scheme aims to:

  • reduce congestion by smoothing the flow of traffic to improve journey times and make them more reliable
  • facilitate economic growth within the region, by providing much-needed capacity on the motorway
  • maximise motorway capacity while maintaining safety

The scheme in detail

The proposed scheme will enable proactive management of the M23 carriageway, including the link roads from/to the M25 at junction 8, the spur to Gatwick Airport and to junction 10.

The scheme includes:

  • converting the hard shoulder to create a permanent fourth lane between junctions 8 and 10
  • converting the westbound hard shoulder along the spur to Gatwick Airport (towards Junction 9a) to create three permanent lanes
  • redefined junction layouts to accommodate the fourth lane - in particular we're creating a dedicated northbound slip road before junction 9 to minimise congestion as traffic leaves the motorway and heads towards Gatwick airport
  • new gantries with variable message signs, providing customers with better information
  • installing new electronic information signs, signals and CCTV cameras - these will be used to vary speed limits and manage traffic flow and incidents
  • installing 12 emergency areas to use in place of the hard shoulder which include emergency roadside telephones and CCTV cameras to improve emergency service response times
  • improving the central reserve and adding a reinforced barrier to improve safety
  • adding new noise barriers in built up areas
  • carriageway widening to provide new acceleration and deceleration lanes to our maintenance facility, Weatherhill Depot
  • creating a new emergency turn-around facility at Coopers Hill Road to minimise our response times to incidents

Environmental impact

We've considered the full range of environmental topics and found that there will be no significant long-term effects. Temporary effects during construction will be slight changes in views, construction noise, disruption to road users and some loss of habitat. The key issues we've considered are:

  • noise and vibration, air quality, ecology and visual impacts in relation to nearby housing
  • the Site of Special Scientific Interest between Mole Gate and Reigate Escarpment
  • protected species and habitats including bats, badgers and great crested newts
  • the setting of conservation areas and heritage assets such as Surrey Hills Area of Outstanding Natural Beauty
  • public rights of way

We've carried out surveys for protected species adjacent to the motorway. Mitigation work will be undertaken within Natural England licenses. The vegetation clearance has to be undertaken at certain times of the year to minimise disruption to wildlife.

We'll retain existing screening planting where possible and propose additional planting upon completion of the scheme to minimise views of the motorway and associated equipment. Much of the M23 between junction 8 and 10 is either in a cutting or on an embankment, so to provide sufficient structural integrity to the new running lane significant earthworks are necessary. We've tried to minimise vegetation clearance, but in some areas it's not always possible.

We're installing new environmental barriers to minimise noise effects. A plan showing the location of the existing and new barriers will be provided in due course. The plans will show the length and the height of the new barriers. The type of barrier being used for this scheme is absorptive as this type takes in noise, reducing the noise energy that reaches residents.

The new lanes (termed lanes 1 and 4) will have low noise pavement. The existing lanes are in good condition and don't require resurfacing as part of this scheme. We'll resurface these lanes when the condition of pavement falls below our required standards.

Project media files and documents

There are no images for this project

Project timeline

Planned roadworks

Roadworks and Events for England

The latest incident information for England's motorway and trunk routes provided by Highways England

Location : The M23 southbound between junctions J8 and J10 . Reason : Roadworks. Status : Currently Active. Period : expect disruption until 06:00 on 30 March 2020. Lanes Closed : All lanes are closed.
Posted: March 27, 2020, 9:08 pm
Location : The M23 northbound between junctions J10 and J8 . Reason : Roadworks. Status : Currently Active. Period : expect disruption until 02:00 on 29 March 2020. Lanes Closed : All lanes are closed.
Posted: March 27, 2020, 8:26 pm
Location : The M25 anticlockwise between junctions J6 and J5 . Reason : Emergency barrier repairs. Status : Currently Active. Period : from 17:13 on 6 January 2020 to 00:01 on 30 May 2020. Lanes Closed : There are lane closures.
Posted: March 24, 2020, 11:00 am
Location : The M23 southbound exit slip at junction J11 . Lane Closures : Lane two will be closed. Reason : Road repairs are planned. Status : Pending. Schedule : From 06:00 on 3 April 2020 to 20:00 on 5 April 2020. Lanes Closed : There will be one of two lanes closed.
Posted: March 24, 2020, 11:00 am
Location : The A23 northbound exit slip to the A264 . Lane Closures : Lane two will be closed. Reason : Road repairs are planned. Status : Pending. Schedule : From 06:00 on 3 April 2020 to 20:00 on 5 April 2020. Lanes Closed : There will be one of three lanes closed.
Posted: March 24, 2020, 11:00 am


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