Drivers have been warned to expect severe traffic jams on many roads on Friday as the Christmas getaway begins, with the M25 around London expected to be one of the worst.
The RAC have urged drivers to avoid "frantic Friday" with congestion expected to peak in the afternoon as 1.3 million Christmas travellers combine with commuter traffic on the last working day before the 25th.
From Friday afternoon onwards, drivers should expect long queues, traffic experts have warned, with the RAC adding that drivers should avoid long journeys "if they possibly can".
December 22 will be one of the worst days of the year on the roads with "incredibly severe" traffic jams, Dr Graham Cookson, chief economist at transportation analysts Inrix warned.
Dr Cookson said he expects the M25 to be "right at the top of the list" of the motorways suffering from the worst congestion on Friday.
He continued that "it doesn't matter which way you're going round it," traffic will be heavy in either direction.
In an effort to ease the predicted jams, Highways England have lifted almost 400 miles of roadworks on motorways and major A roads from 6am on Friday until 2 January.
Despite warnings that the M25 will be heavily congested on "frantic Friday", the worst traffic blackspot is expected to be the A303 at Stonehenge. During last year's Christmas getaway, there were seven-mile tailbacks at the notorious bottleneck.
Roads are predicted to busier than usual as extensive engineering works on the railways will force more people onto the roads.
Elsewhere in the UK, Dr Cookson predicted that the M6 between Merseyside and Staffordshire, M1 and M4 will be "incredibly busy".
The UK's busiest airport, Heathrow, will welcome almost 130,000 departing passengers on Friday.
Aside from the roads, many of Britain's mainline train routes will be partially shut as Network Rail carries out its biggest ever Christmas investment programme.
Some 260 engineering projects over the festive period will disrupt journeys and could force people to make more journeys on the roads, adding to congestion.
Great Western Railway is urging passengers to complete journeys by Saturday "at the latest" as London Paddington will be closed between Christmas Eve and December 27.
Buses will replace trains on the West Coast main line between Preston and Lancaster during the same period. Passengers travelling between London and Glasgow during this time are advised to go via Edinburgh, adding around an hour to journeys.
Coach operator National Express is running its largest ever Christmas schedule to meet increased demand from key locations such as Bournemouth, Cardiff, Leeds, Edinburgh, Portsmouth, Bristol, Glasgow and Manchester.
Airports, ports and international train stations are exceptionally busy with more than 4.5 million people heading abroad over Christmas and the new year.
The following train routes will be affected during the Christmas period while engineering work takes place:
- There will be no train services on Christmas Day
- On Boxing Day and New Year's Day, many train operators will run a reduced train service or no service at all. Travellers are advised to check before they begin their journeys
- London Paddington will be shut from Saturday, December 23 until Tuesday, January 2
- Charing Cross station will be closed from Saturday, December 23 until Tuesday, January 2
- London Bridge station will be closed from Saturday, December 23 until Tuesday, January 2
- Canon Street station will be shut from Saturday, December 23 until Tuesday, January 2
- No Southeastern trains from London Waterloo East from Saturday, December 23 until Tuesday, January 2
- Greater Anglia train servies between London Liverpool Street and Southend Victoria / Southminster / Braintree / Colchester Town / Clacton-on-Sea / Walton-on-the-Naze / Ipswich / Norwich from Saturday, December 23 until Tuesday, January 2
- Buses will replace trains on the West Coast main line between Preston and Lancaster from Sunday, December 24 - Wednesday, December 27. Passengers travelling between London and Glasgow during this time are advised to go via Edinburgh, adding around an hour to journeys