M3 Junctions 2-4a: Smart Motorway

Project status:   Current

Start date:   Autumn 2014
End date:  Main Works Winter 2016

Type:   Major Scheme
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Major Scheme

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

Cost:  Between £138 million and £198 million


Emergency closure

Please see the Road Works section of the Journey Impacts page


M3 J2-4a Smart Motorway Public Information Exhibitions

Thank you to everyone who attended the M3 J2-4a Smart Motorway Public Information Exhibitions which took place on Friday 17 October and Saturday 18 October. A copy of the display boards used at these events can be found on the Publications tab.

For people that attended the exhibition, but did not have time to complete the Customer Feedback Questionnaire, the questionnaire is available to complete online here.

If you have any further queries regarding the scheme, please email the M3 Project Team directly using the following email address: M3​Junction2​to4​aSmartMotorways@​highways.​gsi.​gov.​uk


M3 J2-4a Smart Motorway Scheme Mobilisation

Further to the announcement made by the Government on 8 July 2014 regarding the future of the M3 junction 2 – 4a Smart Motorway scheme, the Highways Agency would like to advise that the required mobilisation works, ahead of construction, are due to commence the beginning of August 2014.

The mobilisation work will consist of:

• The installation of temporary CCTV and SPECS cameras and Comms work.

• Hard shoulder strengthening works.

• Minor surfacing works along the entry/exit slip roads.

• The setting up of site compounds and recovery bases.


What is happening?

We propose to improve the M3 by making it a "smart motorway" between junctions 2 and 4a (13.4 miles / 21.6km). Smart motorways help relieve congestion by using technology to control traffic flows and assist in the management of incidents and providing information to road users. They deliver these benefits at a significantly lower cost than conventional motorway widening and with less impact on the environment during construction. This will be achieved by converting the existing hard shoulder to a permanent running lane. Find out more about Smart Motorways.

We are aware of concerns being raised by residents living close to the project route regarding possible noise and visual intrusion issues. These concerns have been noted and are being considered as part of the project's ongoing development and design.

When and where is this happening?

In the November 2011 autumn statement, the Chancellor announced that the M3 junction’s 2-4a smart motorway (formerly known as managed motorway) scheme would be prepared for construction before 2015. The 2012 Budget confirmed the start of work for this scheme to be in financial year 2013/14, subject to the outcome of statutory processes. Since then, the Prime Minister announced that this scheme would be one of four schemes to be included in a pilot to significantly reduce the delivery time of road schemes.

Why is this happening and what will it cost?

The M3 between J2 and J4a experiences high traffic flows during both peak periods (am and pm) and has a higher than average accident rate.

The March 2008 ' Advanced motorway signalling and traffic management feasibility study' identified this motorway link as a priority for the provision of additional capacity and ministers agreed that smart motorways, as an alternative to widening, should be investigated.

The estimated cost of this scheme is in the range of £138 million and £198 million

How will the scheme be carried out?

Smart motorway schemes have been in operation for a few years on the strategic network e.g.M42 and the concept together with their benefits is better understood. Further improvements have been made to the original concept and 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 camera coverage – although there will no longer be the need for dedicated cameras to open and close the hard shoulder.

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.

The feasibility study for the M3 identified a single option which will allow vehicles run on the Hard Shoulder on the M3 J2-J4a without Through Junction Running (TJR). This option is being further developed to ensure best Value for Money and minimal environmental impact can be achieved. The design is being further developed to ensure best Value for Money with minimal environmental impact.

The scheme will comprise the following elements:

  • MIDAS Queue protection technology
  • CCTV coverage
  • MS4 information signs
  • Lane specific speed signals at certain locations
  • Variable speed limits
  • Speed enforcement
  • Permanent hard shoulder usage as a running lane
  • Emergency refuge areas with emergency telephones
  • Low noise road surfacing (at locations where resurfacing is likely to be required as part of the project)

What are the benefits?

This project will:

  • relieve congestion
  • smooth the flow of the traffic
  • improving safety and reduce serious accidents
  • improve journey times
  • provide better information to road users

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.

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?

Yes, roadworks will be needed accross the scheme.


Emergency closure

Please see Road Works below

Road Works

DateDurationDetailsAllow an Extra
Wednesday 21 January 20159pm - 5.30amEastbound M3 junction 4a to junction 3 full carriage way closure, including junction 4 and junction 4a eastbound entry slip road30 minutes
Thursday 22 January 20159pm - 5.30amEastbound M3 junction 4a to junction 3 full carriage way closure, including junction 4 and junction 4a eastbound entry slip road30 minutes
Friday 23 January 201510pm - 6amEastbound M3 junction 4a to junction 3 full carriage way closure, including junction 4 and junction 4a eastbound entry slip road30 minutes

How will you manage traffic?

We will continue to provide 3 lanes of traffic in both directions utilising both narrow lanes and a contraflow where appropriate.

Will there be diversions?

We will endeavour to keep full closures to a minimum where we are able. However, some closures will be required at night with clearly signed diversion routes in place.

Business Case

M3 Junctions 2-4a Managed Motorway Business Case
Business Case - Information correct as at December 2010


M3 Junctions 2-4a Smart Motorway Environmental Assessment Report
The purpose of the Environmental Assessment Report (EAR) is to assess whether or not significant environmental effects would be likely to occur as a result of construction and/or operation of the Scheme.


M3 J2-4a Public Information Exhibition - presentation
M3 J2-4a Public Information Exhibition - presentation



M1 Junctions 28 to 35a Air Quality Mitigation Summary of Consultation Responses
Responses to the consultation on proposal to introduce a maximum mandatory 60mph speed limit on the M1 between junction 28 and 35a.
M3 Junctions 2-4a Managed Motorway Statutory Instrument Consultation Report
M3 Junctions 2-4a Managed Motorway - Response to the Consultation Report - September 2013