Drivers are being warned to expect long delays on the roads as the Christmas getaway begins - so which routes should you steer clear of and when?
Data supplied to BBC News reveals the exact locations and times on motorways and major roads that traffic experts predict will have the worst delays.
Most roadworks will be lifted by Friday 22 December to give drivers a clear run, but the busiest period is expected to start two days before that.
Traffic data company Inrix said up to four times as many cars as usual would be on the roads.
When and where to avoid
Drivers are being warned to expect delays of more than four hours on the M6 motorway on Thursday 21 December.
The 65-mile stretch from Haydock in Merseyside to Gailey in South Staffordshire is expected to be the most congested route of the getaway.
Inrix, which provides traffic information, has predicted the journey could take some drivers up to five hours and 20 minutes, when it would normally take around an hour in free-flowing traffic. Its predictions are based on an analysis of traffic flows during previous Christmas getaways.
Congestion is expected to rise due to people going shopping, visiting family and friends and going away for the festive break.
Graham Cookson, chief economist at Inrix, said: "Drivers would be well advised to take alternative routes or avoid driving during peak times altogether."
The worst delays are predicted to be:
Wednesday 20 December
- M25 Anti-clockwise Junctions 13 (Staines) to 24 (Potters Bar) - 2 hours 2 minutes of delays, peak time around 16:15 GMT
- M25 Anti-clockwise Junctions 16 (Uxbridge) to 7 (Merstham) - 54 minutes of delays, peak time around 08:00 GMT
- M4 Westbound, Earls Court to Junction 5 (Slough) - 30 minutes of delays, peak time around 16:30 GMT
Thursday 21 December
- M6 Southbound Junctions 23 (Haydock) to 12 (Gailey, South Staffordshire) - 4 hours 21 minutes of delays, peak time around 14:30 GMT
- M74 Westbound Glasgow to Junction 6 (Hamilton) - 34 minutes of delays, peak time around 18:00 GMT
Friday 22 December
- M1 Northbound Junctions 11 (Luton) to 22 (Leicester) - 1 hour 15 minutes of delays, peak time around 11:00 GMT
- M1 Southbound Junctions 19 (Catthorpe) to 12 (Flitwick) - 1 hour 30 minutes of delays, peak time 12:15 GMT
- M1 (Northern Ireland) Westbound Junctions 1 (Belfast) to 15 (Dungannon) - 58 minutes of delays, peak time around 17:15 GMT
- M1 (Northern Ireland) Junctions 15 (Dungannon) to 1 (Belfast) - 35 minutes of delays, peak time around 16:45 GMT
- A720 Eastbound Junctions 1 (Millerhill) to 11 - 19 minutes of delays, peak time around 12:45 GMT
Highways England has promised to complete or pause 400 miles of roadworks from 22 December until 2 January, meaning lanes will be open and temporary speed restrictions lifted.
However, 27 sets of roadworks covering a total of 122 miles will be staying in place because it will be too dangerous to lift them.
Longest sets of roadworks over Christmas
- A1 Junction 51 (Leeming) to 56 (Barton) - Narrow lanes and speed limit of 50mph - 26 miles
- M6 Junction 16 (Crewe) to 19 (Knutsford) - Motorway upgrade - 20 miles
- A14 Junction 31 (Girton) to 38 (near Cambridge) - Road widening - 11 miles
- M62 Junction 30 (Rothwell) to 32 (near Castleford) - Third lane closure, narrow lanes, 50 mph speed limit - 8.2 miles
- M1 Junction 23a (Donington Park) to 25 (near Nottingham) - Motorway upgrade - 8.2 miles
- M6 Junction 8 (West Bromwich) to M5 Junction 3 (near Oldbury) - Structural repairs with speed limits - 7 miles
- M60 Junction 12 (Eccles) to 18 (near Manchester) - Narrow lanes with temporary barrier - 7 miles
- A1M Junction 15 (Sawtry) to A1 Buckden (near Huntingdon) - Road widening - 6 miles
- M1 Junction 19 (Catthorpe) to 18 (near Crick) - Narrow lane - 5.6 miles
- M62 Junction 33 (Ferrybridge) to 34 (near Doncaster) - Third lane closure, narrow lanes, 50 mph speed limit - 5 miles
A Highways England spokesman said: "In our experience the weekend is the busiest time, which is why we have suspended roadworks on the majority of roads, leaving only essential works in place. However, it is not possible to remove all roadworks due to safety reasons."
When to avoid the trains
More than 200 sets of engineering works are planned for the rail network over Christmas.
Network Rail, which controls the UK's railways, says it is the least disruptive time to do the work.
- London Paddington will be closed for four days between Christmas Eve and 27 December
- No Greater Anglia trains between London Liverpool Street and Ingatestone or Billericay from 23 December to 1 January
- Replacement buses between Preston and Lancaster from Christmas Eve to 27 December
- No Southeastern trains to London Bridge, Charing Cross or Cannon Street from 23 December to 1 January
- No trains between Manchester Piccadilly and Manchester Oxford Road on Christmas Eve and from 30 December to 1 January
- No trains between Birmingham New Street and Wolverhampton via Sandwell and Dudley from Christmas Eve to 2 January
- Buses replace trains between Maghull and Ormskirk from 27 December to 7 January
Details of all engineering works are available from National Rail Enquiries.