Londonders heading out of the capital over Christmas have been warned that roads will be far busier than normal due to the impact of the rail strikes.
The RAC expects about eight million journeys to be made on “frantic Friday” and Christmas Eve as leisure traffic for the week peaks at 20 million trips.
Train services will start to wind down from around midday on Christmas Eve, with the last trains leaving central London by 3pm.
RAC spokesman Rod Dennis said: “We are expecting a surge of traffic as motorists swap the train for the car.”
The M25 between junctions 7 to 16 ( its south-western section), the M40, M6 and the M60 are likely to suffer the worst congestion.
“By Friday, we fear it will be a case of ‘jams today and jams tomorrow’ on the roads as millions of people jump behind the wheel to see family and friends — with last-minute Christmas shoppers as well as the impact of another rail strike also leading to an increase in traffic,” Mr Dennis said.
Traffic analysis firm Inrix predicted journeys would take about 15 per cent longer than last Christmas.
Motorists also face higher travel costs — the cost of a tank of petrol is almost £4 more than last year, and a tank of diesel almost £15 more.
Network Rail said people should only travel if “absolutely necessary” on national rail services on Christmas Eve.
The earlier shutdown is due to a strike by RMT members at Network Rail from 6pm on Saturday until 6am on December 27, which will mean many signallers will walk out.
This is in addition to a RMT overtime ban that began at Network Rail and 14 train companies on Sunday and runs until January 2.
Parts of the London Overground will stop running from around 11am on Saturday and on the Elizabeth Line from 2pm — causing problems for last-minute shoppers.
Southeastern said its network, which operates out of Charing Cross, Victoria, London Bridge and Cannon Street, would shut down by 3pm. It advised passengers to travel by midday at the latest.
The last train from King’s Cross to Newcastle and Edinburgh will depart at 11am. The last Leeds train will depart just after midday, followed soon after by the last trains to Liverpool and Manchester. The last Birmingham train is due to leave just after 1pm.
National Highways promised roadworks would be completed or removed and 98 per cent of main roads would be open until January 2.
But its staff belonging to the Public and Commercial Services union began a strike over pay today. This includes road traffic officers and control room staff who monitor “smart” motorways — those without a hard shoulder — across London and the South-East.
People heading overseas have also been warned to expect delays. Border Force staff at Heathrow, Gatwick, Manchester, Birmingham, Cardiff and Glasgow airports will walk out from tomorrow until Boxing Day and from December 28 until New Year’s Eve.
Border Force boss Steve Dann said the Government hoped to keep “most if not all ports open” but would not rule out closures. There are also concerns of a further wave of delays when holidaymakers return home after Christmas.