Motorists have been urged to plan ahead as a section of the M25 in Surrey shuts for the weekend on Friday night.
The AA said many major roads in the South East will be "incredibly busy" as National Highways shuts the motorway between Junctions 10 and 11 in Surrey from 9pm on Friday to 6am on Monday.
This will be the third of five weekend closures of the M25 - which encircles London - as part of a £317 million project to improve Junction 10.
Among the people affected will be many of those travelling to, from and between the UK's two busiest airports, Heathrow and Gatwick.
Meanwhile commuters travelling between Waterloo and southwest London have been hit by delays as a safety inspection is carried out on the railway.
Some lines towards Wimbledon have been blocked for an inspection to be carried out between the Clapham Junction and Vauxhall.
