An official planned closure of the M25 motorway is to take place for only the second time next month as work continues to build a new junction.
The first closure took place last month as part of the construction of the £317 million new junction 10 in Surrey.
The latest closure, between junctions 9 and 10, is due to start at 9pm on Friday 10 May and end at 6am on Monday 13 May. The previous closure was between junctions 10 and 11.
Workers are building a bridge consisting of 68 beams, each weighing 16 tonnes, with a further four beams weighing 40 tonnes, to be installed as part of plans to make journeys safer and reduce pollution.
Motorway bosses have again warned drivers to expect delays and to travel only if necessary, not least because the new diversion routes are longer.
They said: “Following our travel advice instead of satellite navigation system diversions will be key to reducing congestion.”
National Highways made the “unprecedented” decision to close the motorway in March and made “good progress”, demolishing a bridge and installing a gantry.
The work was completed eight hours ahead of schedule which meant that the section between junctions 10 and 11 could reopen to traffic early.
National Highways said: “The project team’s attentions immediately turned to the plans to lift into place concrete beams for the eastern gyratory bridge and another large gantry, which will involve closing a different stretch of the M25.
“This work will take place during a full weekend closure between junctions 9 (A243 Leatherhead) and 10 (A3 Wisley) from 9pm Friday 10 May to 6am Monday 13 May.
“These £317 million essential works are one of five series of improvements to the M25 taking place this year, as part of the government’s £24 billion Road Investment Strategy (RIS2).”
National Highways senior project manager Jonathan Wade said: “This is far from a repeat of the previous closure, as the alternative routes are longer and will be different for over-height vehicles and all other traffic.
“Drivers listened to our advice last time which reduced motorway traffic levels by over two thirds and meant delays were limited.
“Our advice again is please only travel if absolutely necessary and make sure you give yourself extra time if you do choose to use the M25.”
National Highways added: “The junction 10 improvement scheme will see an increase in the number of lanes to make journeys safer and a new junction layout to improve traffic flow.
“It will also make it easier and safer to enter and exit the M25 and reduce the pollution caused by traffic jams.
“This is the second of five full weekend closures of the M25 to take place, with a further three due between July and the end of the year.
“National Highways and delivery partner Balfour Beatty Atkins are continuing to liaise with key stakeholders in the lead up to this closure, including emergency services, Surrey County Council, local businesses and Gatwick and Heathrow airports.
“Local residents, holidaymakers, concertgoers and sports fans should plan their journeys in advance and make sure they allow extra time or make alternative travel arrangements.”
For the closure of the M25 between junction 9 (A243 Leatherhead) and junction 10 (A3 Wisley), planned for the weekend of Friday 10 May and Monday 13 May, there are four diversion routes depending on the direction of travel and the type of vehicle.
National Highways said that each route would be clearly signposted and are as follows.
Diversion route clockwise (from Gatwick towards Heathrow) for most traffic
Leave the M25 at junction 8, A217 (Reigate). Follow the A217 London, Sutton, (A240) Kingston. After 3½ miles turn left on to the A240 Epsom, Kingston. After 3 miles at the Esso roundabout, turn right on to the A24 (A240) Kingston. Continue for 3 miles and turn left on to the A3 Portsmouth, Guildford. Continue for 9½ miles to the M25 and rejoin the motorway at junction 10.
Diversion route clockwise (from Gatwick towards Heathrow) for over-height vehicles (over 15ft / 4.6m)
Leave the M25 at junction 9 A243 (Leatherhead). Follow A243 London, Hook, Chessington. After 6 miles, turn left on to the A309 Esher, Staines, (A3) Guildford, Portsmouth. After 1½ miles turn left to the A307 Esher, Guildford A3. After 4½ miles, in Cobham, turn right on to the A245 M25, Guildford A3, Weybridge, Woking. After ½ mile turn left on to the A3 Portsmouth Guildford. Continue for 1 mile and rejoin the motorway at J10.
Diversion route anti-clockwise (from Heathrow towards Gatwick) for most traffic
Leave the M25 at junction 10 to join the A3 towards London. After 9½ miles at the Hook interchange leave the A3 turning right on to the A240 Epsom, Reigate. Continue for 3 miles to the Esso roundabout and turn left on to the A240 Reigate. Continue for 3 miles then turn right on to the A217 Reigate, M25. After 3½ miles turn left to rejoin the M25 motorway at junction 8.
Diversion route anti-clockwise (from Heathrow towards Gatwick) for over-height vehicles (over 15ft / 4.6m)
Leave the M25 at junction 10 to join the A3 towards London. After 1 mile at the Painshill interchange leave the A3 turning right on to the A245 Cobham (A307 Esher). After ½ mile turn left on to the A307 Esher. Continue for 4½ miles then turn right on to the A309 London, Sutton. Continue for a further 2 miles to the Hook interchange and turn right on to the A243 Dorking. After 6 miles, turn left to rejoin the M25 motorway at junction 9.
National Highways said: “The carriageway between junctions 9 and 11 carries between 4,000 and 6,000 vehicles per hour in each direction between 10am and 9pm at weekends.
“Up to 270,000 vehicles pass through this junction each weekday and it is one of the busiest stretches of road in the UK.
“This phase of work needs to be carried out in May to continue the progress on the delivery of the scheme which is due to open to traffic in summer 2025.
“Future closure dates are subject to change and the third one will be announced as soon as possible following completion of the works on Monday 13 May.
“Drivers can see updates on X (Twitter) by following @HighwaysSEAST.
“For more information about the project and the latest updates including the closures, please visit https://nationalhighways.co.