Half of Britain's drivers are expected to take to the roads
Motorists setting off on breaks over the bank holiday weekend have suffered congestion and delays following a series of incidents on major roads.
The M5 near Bristol had 20-mile tailbacks, while the M25 in Surrey and the M58 in Lancashire were also hit.
Rail users also face delays caused by engineering work, with the West Coast Main Line between London and Scotland bearing the brunt of the disruption.
A mix of sunshine, showers and windy conditions are forecast until Sunday.
Many drivers on the M5 near Bristol were stuck in their cars for more than five hours after lanes were closed between junctions 18a and 19 after an apparent suicide attempt from the Avon Bridge.
Two lanes have now been opened on the northbound carriageway and traffic is starting to move.
An accident on the anti-clockwise M25 in Surrey, between J6 and J5, caused queues of up to six miles, affecting people bound for Gatwick.
Another serious accident led to the closure of a westbound section of the M58 near Skelmersdale in Lancashire.
Two lanes of the M62 were closed in Greater Manchester, while there was also heavy traffic reported on the northern part of the M25, the A303 near Stonehenge in Wiltshire, the M23 in Surrey and the M4 in Berkshire.
The AA predicted congestion would be up by a third compared with a normal weekend, with 14m drivers expected on the roads.
There are 40 sets of roadworks around the country, but the Highways Agency has suspended 31 of its roadwork schemes.
HAVE YOUR SAY
Who wants to wait hours in traffic/airport queues, change trains three times to get to your holiday or pay a premium for everything? I'm going away next weekend instead!
G Bagri, London
On the trains, engineering work means buses will replace trains on more than 1,000 miles of rail routes over the weekend.
Many northbound services from London Euston - run by Virgin Trains and London Midland and Southern - are affected by engineering works on Saturday, Sunday and Monday.
However, the Association of Train Operating Companies has said 3,500 more trains were running than during the last August Bank Holiday and there were 15% fewer replacement bus services than last year.
Although to date more people have been holidaying in the UK this year, travel organisation Abta said a late booking surge meant up to 1.9m Britons would be travelling abroad over the holiday weekend.
Heathrow, Gatwick and Stansted airports are expecting to handle more than 1.5m in and outbound passengers between them.
Abta chairman John McEwan said: "Obviously people have been holding on to their money until they are sure they have enough to go away with and, as a result, we have seen a surge in late bookings."
Meanwhile in the UK, large music festivals are taking place in Reading and Leeds, as well as the Creamfields Festival in Merseyside.
Port of Dover authorities said they expected a 16% increase in holidaymakers using the port compared with this time last year, with 50,000 drivers expected.
Download the Flash plugin from the Adobe website
For more travel information please visit the BBC Travel website.