Three hour traffic jams and cancelled trains are expected as the Christmas getaway starts this week.
Upwards of 20 million individual trips are expected to be taken between now and December 25, with experts warning the busiest times will be Thursday and Friday afternoon as shoppers, commuters and people trying to go away for Christmas.
The anticipated jams are expected to be worse than usual, with extensive disruption to the rail network, with planned engineering work and strikes forcing more people on to the roads.
Data from traffic information service INRIX indicates Wednesday through to Friday will see some significant congestion on major roads, with drivers travelling on the M25, M6 and M40 all likely to face long delays.
On Thursday, delays of up to three hours are expected on one section of the northbound M6, while "frantic" Friday could see drivers queuing for more than an hour and a half.
The predictions are based on analysis of traffic flows during previous Christmas getaways. The route also includes 40 miles of roadworks.
But when it comes to pure leisure journeys over Christmas, traffic is tipped to peak on Boxing Day when some 6.8 million journeys made as drivers head out to see family and friends.
INRIX data scientist Joshua Kidd said: “Our data shows that compared to a normal day, Thursday 20th December will see the biggest increase in cars on the road.
"With most drivers setting out mid-morning, traffic will become heavier over the course of the afternoon and stay congested into the evening.
"But it’s not just those off to see family and friends - commuters, last-ditch shoppers and online deliveries will contribute to clogging the roads.
"Drivers are advised to seek out alternative routes to their destinations and use the latest technology for real-time updates.”
The worst times to travel
Wednesday December 19
Worst time to travel: 3pm to 6.30pm
Best time to travel: After 7.30pm
Worst road for delays: M25 clockwise from J20 to J28 from 3.30pm. Up to 80-minute delay
Thursday December 20
Worst time to travel: 11.30am to 6.30pm
Best time to travel: After 8pm
Worst road for delays: M6 north J15 to J25 from 12.30pm. Up to 181-minute delay
Friday December 21
Worst time to travel: 11.30am to 6.30pm
Best time to travel: After 7.30pm
Worst road for delays: M40 south from M42 (Warwickshire) to J8A (Oxford). Up to 110-minute delay
Saturday December 22
Worst time to travel: 10.30am to 4pm
Best time to travel: Before 9.30am or after 7.30pm
Worst road for delays: M40 north from J8A (Oxford) to M42 (Warwickshire). Up to 61-minute delay.
Sunday 23 December
Worst time to travel: 4pm to 6.30pm
Best time to travel: Before 11am or after 8pm
Worst road for delays: N/A
Monday December 24
Worst time to travel: 11am to 1pm
Best time to travel: At other times
Worst road for delays: M1 north J21 (Coventry/Leicester) to J26 (Nottingham/Ripley). Up to 22-minute delay.
Roadworks
Highways England said 97% of roadworks on motorways and major routes would be cleared by 6am on Friday and would not resume until January 2.
But there are about 40 sets that will have to stay in place because it would not be safe to remove them.
Rail strikes and engineering works
Those planning to use public transport over the festive period could also see delays, due to the large number of planned engineering works, combined with several strikes expected over Christmas.
More than 330 sets of rail engineering works will take place between Sunday 23 December and Tuesday 1 January.
Network Rail said it would do most of the works when no trains are scheduled to run, including Christmas Day and Boxing Day.
Northern rail workers represented by the Rail, Maritime and Transport Union will strike on December 22 and 29 as part of a series of walkouts on Saturdays in December.
Very few trains are expected to run after 5pm on those days.
Details of all engineering works are available from National Rail Enquiries
