M25 junction 10 to junction 16 smart motorway

We’re working up smart motorway design options for this busy stretch of the M25.

Start date 2020-21

End date 2023

Cost £200 million - £400 million

Latest updates

25 January 2019

Smart motorway design options

We're currently working up smart motorway design options that will meet the aims of this scheme.

The government announced that the preferred solution was for a smart motorway with all-lane running at junctions 15 to 16 and also at junctions 10, 11 and 12. This means the existing hard shoulder would be converted into a traffic lane providing five lanes for traffic at junctions 15 to 16 and four lanes elsewhere. Emergency Areas are available in place of the hard shoulder for emergency use.

As part of this we'll assess a wide range of information about the road to establish the nature of the current problems. We have developed an outline design concept which has determined the most appropriate smart motorway operating regime for this section of road. We are currently working on the preliminary design details including the environmental assessment for the scheme. This is to support the concept design with a view of completing this stage by summer 2019.

We are liaising with local authorities and technical stakeholders so that we can take into account their views.

Detailed design to enable construction to start in 2020.

See more updates

Project information

In 2014 the government announced the preferred solution for this stretch of the M25 was to upgrade it to a smart motorway. This means the existing hard shoulder would be converted into a traffic lane so there would be five lanes between junctions 15 and 16 and four lanes elsewhere and there’d be emergency access areas instead of the hard shoulder.

This section of the M25 has the highest traffic flows of any motorway in England. More than 200,000 vehicles use this stretch every day. Where the M25 connects with the M4 and the M40 between junction 15 and 16 is particularly busy as is junction 14 which connects directly with Heathrow Airport.

By converting this stretch to a smart motorway the flow of traffic can be better controlled and there will be less congestion and fewer delays. Upgrading the stretch will also create more capacity.