Friday is expected to be one of the busiest travel days of the year as millions of people embark on the Christmas getaway.
Motorists are being warned to expect delays of almost two hours on some routes as people driving to spend the festive period with friends and family compete for road space with commuters.
Trains will be busier than normal as passengers complete journeys before parts of the network are shut down for Christmas engineering work.
Airports will also have a spike in demand, although the plans of tens of thousands of people have been thrown into disarray after Gatwick's runway was shut due to drone activity on Wednesday night.
Some 59% of UK drivers will take to main roads or motorways on Friday, according to an AA poll of 20,000 motorists.
The breakdown recovery firm warned of queues on major routes and urged people to check traffic reports before setting off.
Research by the RAC and traffic information firm Inrix suggested the M25, M6 and M40 will be the worst traffic hotspots.
Drivers travelling on the southbound M40 from the M42 (Warwickshire) to Junction 8A (Oxford) should expect delays of up to one hour and 50 minutes.
Highways England said it would lift more than 200 miles of roadworks on the country's motorways and major A-roads by 6am on Friday to ensure more than 97% of the network is open for the festive getaway.
The RAC's Mark Souster urged motorists to carry out basic maintenance checks on their cars – such as oil, coolant and screenwash levels and tyre condition – before setting off.
He said: "It's vitally important every driver planning a trip gives their car a once-over to make sure it's up to the job.
"A single breakdown can bring some roads to a grinding halt, slowing down the Christmas getaway for all of us."
The anticipated jams will be compounded by extensive disruption to the rail network, with planned engineering work and strikes forcing more people on to the roads over the festive period.
Strikes are likely to affect routes run by Northern Rail and South Western Railway, while Network Rail is planning extensive engineering work on lines running into major stations such as London Paddington and London Victoria.
Travel trade organisation Abta expects more than 4.7 million people to head abroad from the UK between December 18 and January 2, with Friday the busiest travel day.
Winter sun lovers are heading short haul to Alicante, the Canary Islands and Egypt, while Dubai and India are among the most popular long haul destinations.
Abta chief executive Mark Tanzer said: "Christmas and New Year are always very busy times for the travel industry as people head off to spend their well-earned holidays with family and friends.
"Whether holidaymakers are flying away for some winter sun, travelling to a snowy destination or staying closer to home, this year's festive break looks set to be another busy one.
"It's important people allow extra time for their journeys and check ahead for any disruption if travelling by public transport."