As many as 16 million vehicles could use the roads during the Bank Holiday weekend.
The AA has warned that traffic will build from mid-afternoon on Friday, as crowds flock to festivals and sporting events.
More than two in five motorists are expected to drive this weekend, with almost a third (29%) of those surveyed in an AA poll of 16,000 people, saying they intend to head for the coast.
A total of 24% of day trippers said they intended to visit family while 12% planned to go to leisure events which this weekend include the Reading Festival in Berkshire, Leeds Festival and the Nottinghill Carnival in west London.
Northern Ireland residents were the most likely to take to the road and Welsh drivers the most likely to stay at home.
However, showers may put a dampener on many people's plans with forecasters predicting wet weather for the first part of the weekend.
The two busiest roads this weekend, according to the AA, are likely to be the western section of London's orbital M25 and the A303 through Hampshire, Wiltshire and Somerset. Other busy sections include the M4 from London to Bristol and roads between Winchester in Hampshire and the Dorset coast.
Restrictions will remain in place at 22 locations including a stretch of the M1 near Luton in Bedfordshire and works on parts of the M25.
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