The M25 is set for an "unprecedented" closure this weekend, with planned diversion routes already announced.

Preparations are underway for the first ever complete weekend closure of M25 between junctions 10 and 11.

Between these junctions, the motorway will be shut down in both directions, from 9pm on Friday, March 15 until 6am on Monday, March 18.

The closure is in place to demolish the Clearmount bridleway bridge and install a large gantry, projects that could not be completed without completely shutting down the junctions.

National Highways has continued to warn of the closure on X, telling drivers to expect "significant delays and disruptions" and to "only travel this stretch if necessary".

Planned diversion routes have also been announced by National Highways, following the same route in both directions.

Drivers wanting to travel from junction 10 to junction 11 are advised to take the north bound A3 to Painshill Junction, A245 towards Woking, and then A320 to M25 Junction 11.

Those aiming to travel from junction 11 to junction 10 should take the A320 south towards Woking, the A245 towards Byfleet and Painshill junction, and finally the southbound A3 to junction 10.

National Highways also suggested that taking the M25 in the opposite direction to avoid the closure might be an option for some.

This Is Local London: The diversion routes for the M25 full weekend closure have been mapped outThe diversion routes for the M25 full weekend closure have been mapped out (Image: PA Wire)

However, motorists are advised that these diversion routes will add an extra hour onto their usual journey times.

Daniel Kittredge, National Highways senior project manager, urged drivers to follow the exact route of the diversion, rather than relying on sat nav systems.

He said: "If people move away from diversion routes that we prescribe, it creates additional issues in different parts of the road network.

"The majority of the time that will be local roads, so that really impacts residents in those particular areas.

"Stick to the prescribed diversion route.

"It’s going to be more suitable for your journey."

A total of five more full closures are scheduled along this stretch of the motorway, between now and September 2024, to help ensure better safety, reduce pollution, and improve traffic flow.

This Is Local London: This stretch of the M25, from junction 10 to junction 11, will be closed to demolish the Clearmount bridleway bridgeThis stretch of the M25, from junction 10 to junction 11, will be closed to demolish the Clearmount bridleway bridge (Image: Gareth Fuller/PA Wire)

Project lead Jonathan Wade of National Highways strongly advised that, where possible, drivers stay away from M25 during these closures.

He 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."

READ MORE: M25 Dartford Crossing shut over concerns for man's welfare

He added: "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."

During the hours of 10am to 9pm on a typical weekend, the section between junctions 9 and 11 of the M25 usually sees between 4,000 and 6,000 vehicles travelling every hour in each direction.

For updates or real-time traffic information this weekend, drivers are advised to visit trafficengland.com or follow @NationalHways on X.