This road project has now been completed. This page will be available for 24 months from the date of scheme completion, after which time you will only be able to access this information on The National Archive version of this page.

M25 Junctions 23-27: Smart Motorway

Project status:   Completed

Start date:   February 2013
End date:  November 2014

Type:   Major Scheme
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Major Scheme

Part of our programme of improvements (value >10m)

Cost:  £180 million (subject to final accounts)


Update - November 2014

The section of the M25 between junctions 23 and 27 is now running as a "smart" motorway. The hard shoulder has been converted for use as a permanent traffic lane. This, together with the introduction of enhanced on-road technology to manage traffic flow, will improve the reliability of journey times, providing a boost for businesses and the wider economy.

The new infrastructure and technology that has been added between junctions 23 and 27 includes:


  • 11 gantries that span both carriageways and 5 gantries that span one carriageway
  • 13 refuge areas
  • 26 emergency telephones
  • 79 overhead signals
  • 58 verge mounted signs
  • 57 CCTV cameras


 All Lane Running

As part of our smart motorway initiative, the new road layout for this section of the M25 will involve "all lane running". This means the hard shoul­der is permanently converted into a traffic lane on these sections of the motorway.

Instead of the hard shoulder you will see regularly spaced emergency refuge areas, each one with an emergency telephone. We have also installed CCTV cameras to help us spot incidents and deal with them as fast as possible. Put your hazard lights on to help us.

If you can't make it to an emergency refuge, the smart motorway technology lets us close any lane by displaying a red "X" on the gantries, moving traffic away from the incident and keeping it clear for emergency vehicles. Do not drive in a lane with a red "X" displayed over it.

All lane running increases the capacity of the motorway to reduce congestion and make your journey more reliable. It does this at a lower cost and with less disruption than a traditional widening scheme.


The ‘Get Smart’ campaign has been created to help road users understand the different driving environments, types of signs and signals they will see and what to do in the event of a breakdown when travelling on a smart motorway. Each of these key themes is easily identifiable through a series of icons that appear on the Agency’s website.


How do I find out more information?

For M25 scheme specific information follow the links:

M25 Junctions 5-7 http://​www​.highways​.gov​.uk/​r​o​a​d​s​/​r​o​a​d​-​p​r​o​j​e​c​t​s​/​m​2​5​-​j​u​n​c​t​i​o​n​s​-​5​-7/


You can find out more about smart motorways by visiting the Highways Agency webpage via the following link:



Or follow us on our Facebook page:



If you have any further queries please contact the Highways Agency Information Line by emailing ha_​info@​highways.​gsi.​gov.​uk or calling 0300 123 5000.



This area is now undergoing resurfacing works, please see:

http://​www​.highways​.gov​.uk/​r​o​a​d​s​/​r​o​a​d​-​p​r​o​j​e​c​t​s​/​M​2​5​-​J​u​n​c​t​i​o​n​s​-​2​3​-​t​o​-​2​7​-​R​e​s​u​r​f​a​c​i​ng- for more details.

Where was the project located?

Why was the scheme needed?

What work was carried out?

How did this benefit road users?

How do I find out more information ?

If you have any queries about this project you should contact the Highways Agency Information Line by emailing ha_​info@​highways.​gsi.​gov.​uk or calling 0300 123 5000.

Site office:

M25 Smart Motorway Improvement Works - Junctions 23 to 27
Sanska Balfour Beatty Joint Venture
London Colney, St Albans

Email: communityrelationsj2​3​-​2​7​.​m2​5​@​sbbjv.​co.​uk
Telephone: 01727 744933

The office is opened between 0700 and 1900 Monday to Friday, and 0700 and 1300 on Saturday, closed on Sunday. 

Details of scheduled roadworks are provided to help you plan your journey. Please note that works are weather- and resource- dependent and may need to be cancelled at short notice. This information is not updated in real time so please check Traffic England for current traffic conditions. Diversion timings are approximate and act as a guide only.

Will there be roadworks?

This section of the motorway is now completed and open for all lane running.  There are not any roadworks or lane closures.

Road Works

DateDurationDetailsAllow an Extra
Friday 7 November 2014 to Sunday 9 November 2014n/aThere are not any planned lane or slip road closures.n/a

How will you manage traffic?

There is no traffic management in place now that the scheme is fully open.

Will there be diversions?

Clearly signed diversions will be in place when road closures are necessary.

Public Information Exhibition12 & 13 October 2012
Public Consultation3 December 2012 to 21 January 2013
Start of worksFebruary 2013
Start of work on Central ReserveMid July 2013
CompletionBetween October & December 2014

Business Case

M25 Junctions 23 to 27 Managed Motorways - Business Case
Business Case - Information correct as at December 2010


M25 Junctions 23-27 Smart Motorway - Smart Motorways Leaflet
M25 Junctions 23-27 Smart Motorway - Get smart know your motorways
M25 Junctions 23-27 Managed Motorways - Closure Information Leaflet
M25 Junctions 23-27 Managed Motorways - Closure Information Leaflet - March 2013



M25 Junctions 23-27 Managed Motorways Newsletter No 3
Welcome to our third newsletter. Work to bring junctions 23 to 25 up to all lane running standard has been completed.
M25 Junctions 23-27 Managed Motorways Newsletter No 2
Welcome to our second newsletter. Since our last update, work to convert junctions 23 – 27 to a managed motorway has seen significant progress and is on target.
M25 Junctions 23-27 Managed Motorways Newsletter No 1
Welcome to the first report on progress to convert the M25 to a managed motorway between junctions 23 – 27.


M25 Junctions 23-27 Smart Motorways - Safety Project Control Framework Products
Safety Plan, Hazard Log Report and Safety Report for the M25 Junctions 23-27 Smart Motorways scheme.


M25 junction 23 to 27 Final Use Assessment
M25 junction 23 to 27 Final Use Assessment – Noise Insulation Regulations Assessment
M25 Junctions 23 to 27 Managed Motorways - Summary of Consultation Responses
Summary of Consultation Responses Managed Motorways – All Lanes Running M25 J23 to J27
M25 Junctions 23-27 Managed Motorways - Environmental Assessment Report
For a copy of the Environmental Assessment Report for this scheme please email the team