M3 junctions 9 to 14: smart motorway

We’re upgrading the M3 between junction 9 (Winchester/A34 interchange) and junction 14 (M27 Southampton interchange) to an all-lane running smart motorway. The scheme will link to the forthcoming smart motorway on the M27.

Start date Started
End date 2023-24
Cost £139 million

Latest updates

  • 24 June 2022

    Central reservation work starts soon

    Junctions 12-14

    We’ve been changing the road layout between junctions 12-14 before we begin safety barrier improvement works. This has involved removing existing road markings and installing temporary metal barriers to protect our workforce and the travelling public.

    From early July 2022, we plan to start work in the central reservation between these two junctions. We aim to carry out these works during the day between 8am and 6pm on weekdays and 8am to 1pm on Saturdays.

    Occasional work on Sundays may be required.  

    This will involve removing the old metal safety barriers and lighting columns, cutting and breaking the road surface, digging trenches, drainage work, laying the foundations for the new concrete central reservation, construction of new concrete central reservation itself and sections of re-surfacing.

    There may also be occasions where work needs to be carried out overnight, when lane and/or carriageway closures are less disruptive. If this happens, work will be carried out 7pm to 7am weekdays and 6pm to 8am Saturdays and Sundays

    Junctions 9-12

    From mid-July, we will begin preparation works between junctions 9 and 12. We expect this to last about 8 weeks.

    Work will be carried out overnight between 7pm to 7am weekdays and 6pm to 8am Saturdays and Sundays when traffic levels are at their lowest.

    Thank you for your understanding and patience whilst we carry out this work.

    Read more in our latest newsletter

  • 23 May 2022

    Safety barrier improvements – June 2022

    The M3 junction 9 to 14 all lane running upgrade has been paused. However, we’re still going to carry out important safety barrier improvements on that stretch of motorway and we’re now getting ready to start on the first section of work which will be between junctions 12 and 14 in both directions.

    From Monday 6 June 2022 for about six-weeks, we’ll be creating a safe area to work in and to do this we’ll be changing the road layout. This involves removing the existing road markings and installing metal barriers on both carriageways between junctions 12 and 14.

    This work will be undertaken overnight. There’ll be closures of lanes, entry and exit slip roads and carriageways. When we close the motorway or slip road, a clearly signed diversion will be in place.

    We’ll update our website further when we move into the next section.

    As standard practice for roadworks, once the traffic management is in place mandatory average speed restrictions will be implemented, temporary CCTV cameras will be activated and free recovery service within roadworks will be provided.

  • 04 February 2022

    Getting prepared for work in the central reservation

    Although our smart motorway work has been paused, we are still going to upgrade the existing safety barrier in the central reservation, so it’s made of concrete instead of metal and therefore safer.  

    During 2021 we started preparing the verges and hard shoulder between junctions 9 and 14 and we’re going to resume this early prep work so everything’s ready for us to install narrow lanes in both directions.

    That means you’ll see us doing verge, drainage, and cabling work at the sides of the road throughout February. These activities are all essential for getting the existing hard shoulder ready in both directions so traffic can use it whilst we’re working in the middle of the road.

    We’ll be working simultaneously in both directions between junctions 9 and 14 for about three-weeks.

    This means there’ll be occasional overnight closures of the motorway, lane closures or closures of entry and exit slip roads. Where the motorway or a slip road is closed, a signed diversion will be in place. We have scheduled these closures for weeknights to minimise disruption.

    Please sign up to our email alerts to keep updated about the scheme and to learn more about the motorway upgrade.


  • 01 September 2021

    Progress update - CCTV cameras

    Work continues on both carriageways between junctions 9 and 14, to prepare the hard shoulder ready for traffic.

    From Monday 30 August, we started installing temporary CCTV cameras to ensure we have full coverage of the road and work sites, ready for when construction starts later this year. Installing the cameras and associated cabling should take approximately 15 weeks to complete.

    The CCTV cameras and operation team will monitor the M3 between junctions 9 and 14 in both directions. They’ll use the cameras to monitor changes to the flow of traffic, for example a broken-down vehicle.

    There’ll be occasional overnight closures of the motorway, lane closures or closures of entry and exit slip roads. Where the motorway or a slip road is closed, a signed diversion will be in place.

    Contractors compound

    The construction of the main contractor’s compound started during early August. An entrance directly off Badgers Farm Road and an exit directly onto Otterbourne Road will be created. These link straight onto the motorway network via the Hockley Link road.

    Whilst the access and exit roads are being built, we’ll also start constructing the main compound itself. We’ll level out the field by excavation and foundations will then be laid, providing a hard-standing area for containers, material storage areas, car parking, lighting and a base for our breakdown recovery equipment.

    We’ll need to carry out some of the work overnight when traffic flows are lower. When we do, we’ll use temporary traffic management and temporary lights to minimise any disruption on these roads.

    Please note: all activities are weather dependent and subject to logistical constraints which may delay the planned work and timeframes.

  • 30 April 2021

    Preparation for starting work this summer

    We’ve been clearing vegetation along the side of the M3, undertaking surveys and diverting cables in preparation for upgrading the motorway.

    Later this year we’ll be installing narrow lanes in both directions between junctions 9 and 14, and the hard shoulder will be used as a running lane. This will provide a safe working area in the central reservation, whilst keeping three lanes open during the daytime.

    To prepare the hard shoulder for this, work to strengthen the verges is expected to start early May 2021.

    This means that there will be occasional overnight closures of the motorway, lane closures or closures of entry and exit slip roads. Where the motorway or a slip road is closed, a signed diversion will be in place. We have scheduled these closures for weeknights to minimise disruption.

    Please sign up to our email alerts to keep updated about the scheme and to learn more about the motorway upgrade.

    Timeline of works

    Our key milestones are:

    • Spring/Summer 2021 – On-going site clearance and preparatory work
    • Spring/Summer 2021 – CCTV cameras installed
    • Summer 2021 – Installation of temporary traffic management (narrow lanes and a 50mph speed limit enforced by average speed cameras)
    • Late Summer/early Autumn 2021 – Work to upgrade the M3 will start in the central reservation

    Please note these are indicative timeframes

  • 23 January 2020

    Public consultation results

    Last year we consulted on proposals to implement variable mandatory speed limits on the M3 between junctions 9 and 14. You can now read the results of that consultation in the report.

  • 20 January 2020

    Timeline of works

    From January 2020 we’ll occasionally close one lane of the motorway so we can safely clear vegetation and finish our survey work.

    Our key milestones are:

    • Winter/spring 2020 – Start site clearance and preparatory work
    • 2020-22 – Start building the new smart motorway

  • 06 November 2019

    Preparatory works

    We’ll be getting the M3 ready to become a smart motorway early next year. This will involve clearing vegetation and repairing the hard shoulder.

    We carried out four public information events in September 2019 to gather feedback on our design and inform people about smart motorways. Our brochure and the information banners we displayed are still available for you to view in the project media files section.

    Please sign up to our email alerts to keep updated about the scheme and planned public events, and to learn more about the smart motorways programme.

Project information

Give us your feedback

Visit our M3 junctions 9 to 14: smart motorway feedback tool to have your say. The tool includes an interactive map. You can click on a location to make a specific comment, or give us your general feedback.

ECHO is a one-way feedback tool, so if you’d like a response to your feedback you can email the project team at: M3J9-14SmartMotorway@nationalhighways.co.uk

The M3 motorway is a key part of the strategic road network and provides a vital economic link from the Midlands (via the A34) and London to the major ports of Southampton and Portsmouth on the south coast (via the M27).  

By 2036 this 10-mile stretch of the M3 is forecast to carry at least 20,000 more vehicles a day compared to 2015. We’re converting it into a smart motorway, so it has capacity for these forecast levels of traffic. 

It involves changing the hard shoulder into a running laneadding more signs, deploying variable speed limits from overhead gantries and building emergency refuge areas.

Between junction 9 (Winchester) to 13 (Eastleigh), the M3 will operate four-lanes in each direction. This is known as ‘all-lane running’ and involves the existing hard shoulder being converted into an additional lane for vehicles.  

Road users driving northbound and joining the M3 at junction 14 where the roads converge from the M27 eastbound, westbound and from Southampton will see the M3 operate four lanes and a hard shoulder up to junction 13.  

For road users driving southbound from junction 13 (Eastleigh) towards junction 14 (Southampton), the road will transition from four lanes with no hard should shoulder and then split into two separate roads to link to the M27 East and West. 

The section of the M3 linking to the M27 eastbound will feature two lanes and a hard shoulder. The section of the M3 linking to the M27 westbound will comprise three lanes with no hard shoulder. The road layout into Southampton will remain as it is now.  

The section from after junction 13 (Eastleigh) to junction 14 (Southampton) is a variation of smart motorway known as a ‘controlled motorway’.


Frequently Asked Questions

How long will the M3 central reservation upgrade work take?

We expect the work to take about 12 months, the project should be completed during Summer 2023.

The project is budgeted to cost approximately £70 million.

The section of steel barrier between junction 12 and 14 was installed around 1991 and the section through junction 9 to 12 was constructed in about 1995.

Steel barriers have a minimum design life of 20 years but can last much longer when not exposed to harsh weather conditions.

Concrete barriers are much stronger than metal ones and significantly reduce the risk of vehicles crossing over from one carriageway to another, improving safety and reducing the duration of incident-related congestion.

They are virtually maintenance free and will last twice as long as metal barriers, with far less need for closures for routine repairs.

We are sequencing our plans with other schemes in the area:

  • M27 junctions 4 to 11 motorway upgrade

    Work to upgrade the M27 between junctions 4 and 11 to an all lane running motorway is near completion. We are however holding regular meetings with the M27 project team to co-ordinate planned work and closures, minimising the impact on road users. It is expected, should there be a connection of the temporary traffic management for each project (around M3 junctions 13 and 14), there will not be an increase of additional delays.

  • M3 junction 9 improvements scheme

    The M3 junction 9 improvements project is currently undergoing Development Consent Order planning process. The scheme isn’t due to start until late 2023/early 2024. We are holding regular meetings with the scheme to keep them updated with our project. These meetings will continue throughout the duration of the M3 9 to 14 safety barrier improvements project.

We’ve taken into account and thoroughly studied the environmental aspects of the central reservation upgrade. It has been concluded there will be no significant effects on the environment either during construction or once the central reservation upgrade work has finished.

One of the activities for the central reservation safety barrier improvements work is removing the unintended vegetation and shrubbery growth from within the central reservation.

When removing vegetation, we do so in a manner to eliminate risk to the harming of wildlife. The necessary checks will be undertaken prior to clearance to ensure that animals and birds are identified, and appropriate controls are implemented if required.

We don’t expect our work will be exceptionally noisy. Work will primarily take place during the day. There will be some overnight activities which can’t be done during the daytime, such as temporary traffic management installation.

We do understand that noise from the construction work will be different to what you are used to hearing and may therefore be more obvious.

We’ll be monitoring noise, where possible, during construction. The results will be shared with the Local Authority Environmental Health Officer if required.

Yes – some work will have to be done at night which means we’ll need to close carriageways or slip roads. All closures will be carefully planned to reduce the impact on local roads, clearly signed and approved diversion routes will be in place.

The latest project announcements can be found on this project webpage where you can also register your email address and subscribe to email alerts.

It may appear that work is only taking place on a small section of the road, or at only one end.
During works and closures the workers are entitled to scheduled breaks, as well as having to be briefed regularly by site foremen to ensure safety regulations are understood before carrying out the planned works.

Some of the activities that we carry out can be restricted by poor weather conditions, and work may be temporarily halted as a result. For all these reasons there may be occasions when the workforce is unseen on your travels.

To create the working space for construction to take place, the running lanes need to be altered and narrowed to ensure three lanes are provided. The driving environment around roadworks is likely to be very different to normal. There will be changes to the normal standard of carriageway as well as works vehicles entering or leaving the site. Additionally, excavations, works vehicles and equipment can pose additional risks, and the safety of road users is always our primary consideration.

A reduced speed limit is put in place to give drivers more time to concentrate on this changed environment and reduce collisions. It takes many weeks to install altered lanes with temporary traffic management, so cannot be easily removed.

Neither we, or our contractors, are responsible for any speed enforcements.

If your vehicle has a problem, or you get into trouble on a motorway with roadworks, stay calm and try to exit at the next junction or motorway service area. If you cannot leave the motorway, you should:

  • Move over as far left as possible towards the verge
  • Put your hazard lights on to warn other drivers and help our control room staff spot you on CCTV. Traffic passing through road works is monitored by CCTV 24/7
  • If you are in the left-hand lane and it is safe to do so, exit the vehicle via the left-hand door. Wait behind the barrier if possible
  • If you cannot exit the vehicle, do not feel it is safe to do so, or there is no other place of relative safety, remain in the vehicle. Keep your seat belt on and dial ‘999’

Whatever part of National Highways' network you’re driving on, we want you to stay safe and know what to do if anything goes wrong.

Check our Road Safety pages for information about what to do when you see a Red X and driving on motorways.

If you are unable to follow our breakdowns advice for any reason, have stopped in a live traffic lane or feel your life is in danger:

  • Stay in your vehicle with your seatbelt(s) and hazard lights on
  • Call National Highways on 0300 123 5000 (or 999 if it is an emergency)
  • Tell the operator if you are disabled and/or a vulnerable motorist such as an older person or travelling alone
  • Keep details of your breakdown provider with you. Your breakdown provider may give you additional instructions in the event of a breakdown.

The emergency services will alert the control room and they will close motorway lanes with Red X(s) and send other help if required, such as a Traffic Officer.

Always carry any medication you need with you and prepare for your journey in advance.
People who are unable to use the emergency roadside phones due to a hearing, speech or physical impairment can contact us via text on 0738 028 3600 for roadside assistance.

We also offer British Sign Language users the SignLive service for getting in touch with our customer contact centre.

Both of these services are available 24 hours a day, every day of the year.’ 

Find out more about what to do in the event of a breakdown on a UK motorway.

Traffic information

Information about scheduled roadworks and events on our motorways and major roads.

Sign up for updates!

Keep up to date with what's happening on this scheme by signing up to our updates.