M25 Junctions 23-27: Smart Motorway

Project status:   Current

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.

What is happening?

We have developed proposals to provide smart motorway (previously known as managed motorways) on the M25 between junctions 23 and 27. Smart motorways help relieve congestion by using technology to vary speed limits. They also allow the hard shoulder to be used as a running lane to create additional capacity. They deliver these benefits at a significantly lower cost than conventional motorway widening and with less impact on the environment during construction.

Find out more about smart motorways.

When and where is this happening?

This scheme is complete.

Why is this happening and what will it cost?

The M25 is one of Europe's busiest motorways, handling around 200,000 vehicles every day. It is at the core of our network and is suffering from increasing congestion levels and journey times. We need to manage traffic flows better and to help achieve this we have already widened the carriageways from junctions 16 to 23, and from junctions 27 to 30, from 3 to 4 lanes in each direction.

The Secretary of State decided that this section of motorway could be improved by the introduction of a system to replace the hard shoulder with a fourth running lane (otherwise known as Smart Motorways - All Lanes Running).

Our aim is to provide the minimum amount of improvements necessary to deliver the safe operation of smart motorways.

Widening of the M25 is one of the recommendations of the Orbit Multi Modal Study which reported in November 2002. The study was tasked with addressing the problems of the M25 motorway and the orbital transport corridor around London. The study involved widespread public consultation and looked at the current problems and potential solutions to them. The report recommended that most of the dual 3 lane sections of the M25 should generally be widened to dual 4 lanes. The other sections to be widened were:

M25 Jct 16 to 23 (M40 - A1 (M)) - 21.8 miles (35 kilometres) - CompletedM25 Jct 27 to 30 (M11 - Dartford) - 14.3 miles (23 kilometres) - CompletedM25 Jct 5 to 7 (Sevenoaks to Redhill) - 12.2 miles (16 kilometres)M25 Jct 1b to 3 (Dartford - M20) - 3.1 miles (5 kilometres) - Completed

* The estimated outturn cost of £195 million was approved by the Secretary of State in November 2012 prior to the start of construction. The current forecasted cost for this scheme is £180 million as at the end of November 2014 (subject to Final Accounts).

How will the scheme be carried out?

A number of cameras, information signs and signals on gantries will be installed as part of the improvement scheme. As the scheme design progresses we will provide more information on the location of these features. Using our knowledge of operating the M42 and M6 managed motorway schemes we have developed the smart motorway concept. These developments include permanently converting the hard should to a running lane and developing the design so that schemes will have:

  • Fewer overhead gantries which span the whole motorway.
  • Fewer signals over each lane and more verge mounting signing.
  • Comprehensive CCTV cameras – although there will no longer be the need for the dedicated cameras and operating systems required for opening and closing the hard shoulder.

Signs and signals will still be used to inform drivers of conditions on the network and when variable speed limits are in place.

What are the benefits?

This project will relieve congestion and smooth the flow of the traffic, improving safety and journey times. These benefits will also support economic development in the region.

We already have evidence of the benefits that a smart motorway scheme can bring. The first smart motorway scheme opened to traffic on the M42 motorway in 2006. Recent analysis of the data gathered since opening has found that journey time reliability improved by 22 per cent and reduced emissions by up to 10 per cent due to traffic flowing more smoothly.

In addition, personal injury accidents have reduced by more than half (55.7%) since hard shoulder running was introduced. There was also an overall reduction in the severity of accidents with zero fatalities and fewer seriously injured.

How do I find out more information ?

More information will be posted on this project page as it becomes available. You can subscribe to be alerted when updates are made.

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. 

Making Part 1 Claims

Part 1 claims for the M25 junctions 23 to 27 Smart Motorway Scheme will be processed by the National Part 1 Claims Team in Bedford. Find out more about Part 1 claims.

Part 1 claims submitted in respect of the M25 Junctions 16 to 23 and junctions 27 to 30 schemes are being managed by the Design Build Finance and Operate (DBFO) company Connect Plus. All requests for further information relating to Part I claims on these schemes should therefore be directed to Connect Plus who can be contacted at Connect Plus House, St Albans, South Mimms, Potters Bar EN6 3NP or by telephone on 02033 868500. The contact for Part I claims at Connect Plus is John Worsfold.

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 at:M25J23toJ27MM@highways.gsi.gov.uk