M25 closure: Heavy delays expected this weekend as motorway closes as part of A3 project - diversion

Drivers have been warned to only travel if necessary with the M25 due to shut between junctions 10 (A3 Wisley) and 11 (A320 Chertsey) from 9pm on Friday, March 15 to 6am on Monday, March 18. Those who do need to travel have been urged to allow extra time for their journeys or find an alternative route or way of travelling.

The closure is taking place to allow work to demolish the Clearmount bridleway bridge and install a very large gantry. It will be the first of five closures between now and September 2024, with other closures also taking place on the A3. Without a full closure, it would be impossible to safely demolish the overbridges and install the new gantry, National Highways has said.

The Junction 10 improvement scheme will see an increase in the number of lanes which National Highways says will make journeys safer and improve traffic flow, making it easier and safer to enter and exit the M25 and surrounding area. It will also reduce the pollution caused by traffic jams.

National Highways has warned those most likely to be affected are concertgoers, sports fans and holidaymakers travelling to London. Those travelling to Gatwick and Heathrow airports via the A3 and M25 may also be affected.

Jonathan Wade, National Highways Project Lead, said: “Drivers should only use the M25 if their journey is absolutely necessary. This is the first of five full closures of one of the busiest junctions on our road network. We have spent months planning for these closures and making sure there are diversion routes in place, but there will still be heavy congestion and delays.

“These improvements will bring long-term benefits to drivers who pass through this stretch of the M25, not to mention pedestrians, cyclists and horse riders who will also see positive changes in the area.”

Both National Highways and contractor Balfour Beatty have liaised with key stakeholders in the lead up to this closure including emergency services, Surrey County Council, local businesses and Gatwick and Heathrow Airports. Those affected by closures have been also been notified in advance while nearby event venues have also been kept up to date with this latest information on the project and associated closures both on the M25 and A3.

The carriageway between junctions 9 and 11 carries between 4,000 and 6,000 vehicles per hour in each direction between 10am and 9pm on a weekend.

This work needs to be carried out now to continue the good progress on the delivery of the scheme which is due to open to traffic in Summer 2025. National Highways has planned these closures to make sure they do not conflict with holiday periods or key events in the area. The next full closure of the M25 is due to take place in April to allow for the installation of the new Clearmount bridleway bridge. Dates are subject to change.

Later this year, National Highways will also look to install the new Cockcrow Green Bridge which will be the project’s centrepiece. This will be the UK’s first ever heathland bridge connecting Ockham and Wisley commons for the first time and provide a safe, natural corridor for local wildlife.

Drivers can use real-time traffic information for England’s motorways at trafficengland.com as well as X (Twitter) updates by following @NationalHways. Any closures will also be visible on satellite navigation.   

For more information about the project and the latest updates including the closures and diversion routes, visit https://nationalhighways.co.uk/our-roads/south-east/m25-junction-10/