TODAY is set to be the busiest day of the summer for commuters, with an estimated 3.4 million cars taking to the road.

The warning comes from insurers the RAC, who predict that the weekend will see nine million cars taking families off on their holidays.

For most, this weekend marks the start of the annual six-week school summer holiday period.

The RAC expects that there will be up to 36.5 million leisure journeys made by car in the busy 17-day period up to Sunday August 6.

Rod Dennis, RAC traffic spokesman, said: "This weekend will bring unwelcome customary chaos to Britain's major roads as people flock to take advantage of the first week or two of the summer holidays on home soil.

"Sadly, for many the much-needed family summer holiday might begin stressfully, as long tailbacks are inevitable - particularly in the South West on the M5, which is the main conduit to the beaches of Devon and Cornwall."

Among the anticipated traffic hotspots are: the M5 between Bristol and Taunton; the A30 and A38 from Exeter to Cornwall; the A303 from Andover to Illminster; and the M4 between Cardiff and Swansea.

The RAC's Rod Dennis said: "The best advice is always to try to travel when the vast majority of motorists aren't - very early in the morning or late in the evening."

For those who couldn't travel at those times, the RAC's Rod said that a "healthy dose of patience" would be the best antidote to long queues.

For details on planned roadworks, visit: www.highways.gov.uk/traffic-information.