Drivers, particularly holidaymakers heading to Heathrow and Gatwick Airports, have been warned to plan ahead as part of the M25 will be closed this weekend.
The motorway will be closed between junctions 10 and 11 in Surrey from 21:00 BST on Friday to 06:00 on Monday.
It is the third full weekend closure on the M25 this year as part of an ongoing £317m project to reduce congestion and improve traffic flow.
The RAC urged those travelling to airports to leave “even earlier than usual” and said diversion routes will be in place.
The closure will allow for the installation of a new bridge on the roundabout of junction 10.
Among the road users affected will be many of those travelling to and from Heathrow and Gatwick.
National Highways has advised drivers to avoid the area and complete “journeys in other ways” where possible, with delays likely along diversion routes.
Alice Simpson, RAC breakdown spokeswoman, said travelling to London will be “easier by train and tube” but she acknowledged people airport-bound are likely to travel by car “especially if you’re loaded with luggage”.
She urged holidaymakers to “plan ahead, check their route, leave even earlier than usual and make sure vehicles are road ready”.
The project, due to be completed in summer 2025, will increase the number of lanes at junction 10, which is one of the UK’s busiest and most dangerous motorway junctions.