Everything you need to know as works shut M25 motorway between Junction 10 and 11 in Surrey

The M25 will close in both directions once again in Surrey to allow engineers to work on one of the country's busiest and most dangerous motorway junctions. Motorists are warned not to use satnavs if they have to travel this weekend.

A chunk of the M25 will once again be closed this weekend as part of £317m works on one of the UK's busiest and most dangerous motorway junctions.

Engineers are constructing a new bridge near Junction 10 in Surrey in a bid to cut congestion and improve safety.

This weekend's closure is the third so far this year, impacting a stretch through which up to 6,000 vehicles pass in each direction between 9am and 10pm on weekends.

Holidaymakers are warned to plan ahead, while the Euros final, festivals and a potential upturn in the weather could result in more cars taking to the road than usual.

Here's what you need to know about the latest closure.

Where is the closure and what's the diversion?

A 10-mile diversion will be set up to replace the route between Junctions 10 and 11, which will be shut from 9pm on Friday 12 July until 6am on Monday 15 July.

From Junction 10 to 11 the route will be:

Northbound on the A3 to Painshill Junction, A245 towards Woking and then the A320 to M25 Junction 11.

From Junction 11 to 10 it looks like:

South on the A320 towards Woking, A245 towards Byfleet and Painshill junction, then southbound on the A3 to Junction 10.

How bad could it be?

The first closure was in March, followed by another in May, which both went "well", according to National Highways senior project manager Jonathan Wade.

This weekend's diversion matches the one set up in March, when traffic was not as bad as feared, despite some congestion stretching across two miles at one point.

Amanda Boote, of Woking Borough Council, said at the time: "It's actually been a lot better than we expected, it's not gridlocked in the way that we thought it would be."

But with England playing in the Euros final on Sunday, many may head to screenings in central London or watch at a friend's house.

The closure could also disrupt journeys to Dover by England fans embarking on cross-Channel trips before driving to Berlin for the match.

There's also the Goodwood Festival of Speed, Wireless and British Summer Time, while families may head to Thorpe Park.

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And with slightly improved conditions forecast, the AA's Chris Wood warns it's likely to be "incredibly busy in and around London, particularly the M25 junctions 10 to 11".

"We advise drivers to plan their journey accordingly, avoiding the west side of the M25 if possible, but if not to expect delays and stick to the detour routes," he added.

And there's one key bit of advice all drivers are urged to heed.

Ignore your satnavs

The diversion sticks to A roads, but National Highways is concerned satnavs could direct drivers to minor roads after leaving the M25.

This would cause congestion in residential areas.

These fears were not realised during the first two closures, with motorists mostly sticking to the diverted route.

"We would urge all drivers to follow the official diversion route as this is the best chance of reaching your destination in good time," Mr Wade said.

"Please ignore your satnavs and follow our diversion route instead."

Airport warnings

It's especially important for holidaymakers to plan ahead if they're taking off from Heathrow or Gatwick, the country's two busiest airports.

The RAC is advising people to travel "earlier than usual" if their journeys will be affected by the closure.

RAC breakdown spokeswoman Alice Simpson said: "We're asking holidaymakers to ensure they plan ahead, which means checking their route before they set off, leaving even earlier than usual and, importantly, making sure their vehicles are road ready by checking the oil, coolant and tyres to give themselves the best chance of avoiding a breakdown."

What's all this for?

Shutting the motorway this weekend will enable the construction of a new bridge south of Junction 10.

The project, which is due to be completed in summer 2025, will increase the number of lanes at Junction 10 by four.

Will the diversion take me through a ULEZ zone?

No, if motorists stick to the diverted route they will not go through any part of the ULEZ area.

The last closure, in May, did take drivers through a section of the ULEZ, but nobody was penalised as long as they stuck to the official route.

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