Right, let’s get the facts out of the way, like taking a nasty vitamin. National Highways is ripping up the Wisley Interchange (M25 Junction 10 and the A3) because it currently breaks the laws of physics every rush hour.
They’re adding new bridges, longer slip roads, and something called a “continuous flow” system. In theory, this means you won’t have to sit through four traffic light cycles just to merge onto the A3. In practice, it means the next two years will feel like a Gran Turismo loading screen.
The government says it will reduce delays by 40% when it’s done in 2026. That’s the same government that said Brexit would be easy, so... let’s just keep our expectations in the glovebox.
The Specific Closures That Will Ruin Your Tuesday
Here’s where it gets personal. The slip road from the M25 clockwise (that’s the one heading towards Heathrow if you’re lost) to the A3 southbound is shut. Shut. Like a pub during a royal funeral.
Also under the knife: the A3 northbound entry to the M25 clockwise. And the bridge over the A3 at the interchange. They’re literally demolishing it. If you need to get from Cobham to Byfleet, you might as well learn to teleport or buy a canoe.
M25-A3 Wisley Interchange plans: San Domenico and RHS Wisley access
And here’s the kicker: the diversion is eighteen miles long. That’s not a “detour,” that’s a weekend road trip to deliver a single sandwich.
