Commuters and are being warned of travel chaos over the weekend as up to four million cars took to the road for May Day bank holiday excursions and major rail engineering works began.
Drivers were affected by a number of accidents on major roads in the early hours of the morning, including one at the start of M40 at Denham in Buckinghamshire.
There were also accidents on the M42 near Hockley Heath in the West Midlands and on the A1(M) near Aberford in West Yorkshire.
The RAC is expecting 3.8 million cars on the road on Saturday, about 3.2 million on Sunday and around 3.5 million on Bank Holiday Monday, increasing the potential for heavy traffic.
RAC head of external affairs Pete Williams told the Press Association: "We're expected this evening's rush hour to be especially busy, with commuter and extra leisure traffic sharing the roads."
Meanwhile, those travelling by train this weekend will face disruptions caused by a major programme of Network Rail (NR) engineering work.
A number of London stations will be affected, with Liverpool Street station services starting and finishing at Ingatestone station in Essex on Sunday and on Monday.
Charing Cross, Cannon Street, Waterloo East and London Bridge high level platforms 1-3 will be closed at various points over the weekend, with no Southeastern services from these four London stations, and diversions into Victoria/Blackfriars or trains terminating at New Cross in south London.
Two of the four lines between Slough and London Paddington will be closed over the weekend while there will be an amended timetable for trains using Waterloo.
Work is also taking place around Wolverhampton, Stafford and Crewe, resulting in amended services on som Virgin Trains, London Midland, CrossCountry, Transpennine Express (TPE) and Arriva Train Wales services.
Work on new signalling means buses will replace trains on Sunday and Monday between Birmingham and Wolverhampton, while major work around Glasgow will lead to changes to Virgin, ScotRail, TPE and CrossCountry services over the weekend.
NR said more than 95 per cent of the network would run as normal despite the work, adding that the work has been timed to minimise disruption to passengers over the weekend.
Additional reporting by PA
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