Drivers are being advised to plan for delays on popular routes this weekend as the bank holiday coincides with the start of half term and a spell of warm weather.
Between 15-20 million UK motorists are expected to embark on leisure trips this weekend, according to AA research.
Roads will be busy from late afternoon on Friday as commuters battle for space with those making an early start on their getaway trips.
AA patrol of the year Vince Crane predicted that congestion will be "pretty intense".
He said: "The best indicator of traffic levels is the weather.
"Forecasters say it is likely to be warm and sunny and that's going to tempt people to travel further, so motorways and coastal routes are likely to be busy."
RAC traffic spokesman Rod Dennis said: "Motorists planning on covering any significant distance should try to avoid Friday afternoon and evening and get away early on Saturday or Sunday to miss the worst of the jams.
"But with the UK's constrained road space, and with road traffic at an all-time high, it doesn't take much for congestion to occur so the message is to expect queues on some of the busiest routes."
Anyone hoping to escape traffic jams by taking a train are urged to check whether their route is affected by engineering work.
Network Rail is carrying out projects across Britain between Saturday and Monday.
No trains will run between Birmingham New Street and Coventry due to signalling work, causing disruption for Aston Villa fans travelling to Wembley on Saturday.
Other rail projects taking place over the bank holiday include:
- Track renewal in the Penrith area on Saturday and Sunday resulting in rail replacement buses for some journeys on the West Coast main line
- Ongoing improvements on the Halton Curve and Weaver-Wavertree projects from 12.15pm on Saturday until 11.55am on Monday, affecting some services in and out of Liverpool Lime Street
- Electrification work means no trains will run between Manchester and Bolton on Saturday, Sunday or Monday
Martin Frobisher, a route managing director for Network Rail, said the upgrades will provide "better, more reliable journeys" for passengers who travel from London to Carlisle via the West Midlands and the north-west of England.
He went on: "The work we do is essential to keeping people and goods moving.
"There is never a good time to carry out big pieces of work but we plan it over bank holidays which are traditionally quieter times to affect the fewest number of people."