Image copyright Getty Images Image caption Traffic is expected to be heavy from 12:00 GMT on Friday

Drivers are being warned to expect long tailbacks on the UK's busiest roads as millions of people travel for Christmas

The RAC and AA motoring groups have warned sections of the M1, M5, M6 and M25 are likely to see heavy delays.

Highways England said 98% of roadworks on motorways and major A-roads had been lifted or completed by 06:00 GMT on Friday.

Rail passengers have been advised to plan ahead due to engineering works and strikes.

Friday is expected to be the busiest day for people going abroad for Christmas, according to the Association of British Travel Agents (Abta).

It said the Canary Islands, Cape Verde, Morocco, Turkey and Egypt were popular short-haul destinations while the long-haul market had seen high demand for Dubai and Goa.

Abta chief executive Mark Tanzer said people should leave extra time to get to airports because the roads would be busy.

Getty Worst times to drive before Christmas 12:00 - 19:00 Friday

10:00 - 15:00 Saturday

10:00 - 16:00 Sunday

10:00 - 15:00 Monday

14:00 - 18:00Tuesday Sources: RAC and Inrix, all times GMT

The RAC and traffic data company Inrix estimated about 4.7 million "leisure" journeys would be made by car on Friday and warned of delays as Christmas traffic mixes with commuters.

Ben Aldous from the RAC said: "While Christmas Day is still a little way off, it looks as though millions of drivers are planning to complete their getaway trips this week.

"Unfortunately, when you add in the prospect of unsettled weather, with heavy rain and strong winds in some parts, these are likely to be pretty unpleasant drives for many of us."

Inrix has also predicted places likely to have some of the longest delays, based on analysis of traffic flows during previous Christmas getaways, as well as things like planned roadworks and events.

Where will traffic be worst?

The M1 between Bedfordshire and Northamptonshire is expected to be heavily congested on Saturday and Sunday, along with the northern and western sections of the M25 around London.

Delays of up to an hour are also possible from Friday morning on the M6 between Birmingham and Wolverhampton, Inrix warned.

Christmas getaway traffic Estimated delays on motorways and worst times to travel Road Possible delay Time M25 Thorney to Watford 45 minutes 14:15 Friday M1 Northampton to Watford 45 minutes 15:45 Friday M40 Banbury to Bicester Up to 45 minutes 13:15 Saturday M1 Flitwick to Daventry Over 30 minutes 14:15 Saturday M1 Flitwick to Daventry Over 90 minutes 12:00 Sunday M25 Warwick Wold to Tatling End Up to an hour 12:15 Sunday M5 Almondsbury to Bridgwater Over 45 minutes 15:30 Sunday M40 Gaydon to M42 Umberslade Over 40 minutes 18:45 Sunday M25 Thorney to Watford Over an hour 14:45 Monday

The AA said it expected traffic to reach a peak on Friday after 16:00, with the M5 between Bristol and Weston-Super-Mare likely to see hold-ups.

Image copyright PA Image caption Most roadworks on major routes will be lifted by Friday but some of those staying in place are those creating smart motorways

Where are the roadworks?

Highways England said it would remove 98% of its roadworks by Friday morning, freeing up more than 800 miles of motorways and major roads, but that the rest would have to stay in place for safety reasons.

The longest stretch of roadworks to remain in place is 43 miles on the M4 between junction six, near Slough, and junction 12 near Reading. The work is part of the £848 million smart motorways project to open the hard shoulder to traffic.

Other smart motorway roadworks staying in place include 20 miles of the M62 near Manchester and 19 miles of the M6 near Stafford.

Roadworks staying in place for Christmas Longest stretches that cannot be lifted for safety reasons Road Miles M4 J6 to 12 (near Wokingham) 43 M62 J10 to 12 (near Manchester) 20 M6 J13 to 15 (near Stafford) 19 M27 J4 to 11 (near Southampton) 16 M1J13 to 15 (near Milton Keynes) 15 M6 J2 to 4 (near Birmingham) 14 A14 J31 to 24 (near Cambridge) 11 M23 J8 to 10 (near Gatwick) 10 M4 J3 to 4B (near Hayes) 8 M20 J3 to 5 (near Maidstone) 8

There is more information on the Highways England website and also at Traffic Scotland, Traffic Wales and Trafficwatch Northern Ireland.

Image copyright Network Rail Image caption Network Rail does engineering work over Christmas because it is quieter and fewer people travel by train

Will my train run?

No trains run on Christmas Day, 25 December, and it is normal for only a few to run on 26 December.

Network Rail is working on 386 engineering projects between Friday and 2 January.

Most lines will remain open as normal but London Paddington station will be closed from Tuesday, Christmas Eve, until Friday 27 December, with no trains running.

Changes to services include:

Paddington: No trains between 24-27 December and a reduced timetable will be in effect from 28-31 December

King's Cross: Reduced timetable on Friday 27 December

Liverpool Street: Services to Stansted Airport to start and terminate at Tottenham Hale on 26 December

Ashford International to Canterbury West: Replacement buses from 27-29 December and Southeastern high-speed and Eurostar trains will not stop at Ashford from 26-29 December.

Southend Victoria and Southminster: Replacement buses to and from London Liverpool Street from 27 December to 1 January

Replacement buses between Bristol Parkway, Chepstow, Cwmbran, Ebbw Vale Town and Cardiff Central from 27 December to 2 January

Edinburgh Haymarket: Replacement buses to and from Edinburgh Waverley from 27-28 December

What about strike action?

Services on South Western Railway (SWR) are affected by strike action until Thursday 2 January.

The operator is running a reduced timetable, warning peak services are likely to be busier than normal and replacement buses on some routes.

A spokesman for SWR said an alternative timetable would be in place for the week starting 23 December.

The strikes may mean Great Western Railway services are busier than normal as SWR passengers use them as an alternative.

The dispute between SWR and the RMT union is over the role of guards on trains.

Planned strike action on West Midlands Trains on Saturdays in December was called off.