Around four million cars were taking to the road today at the start of a May Day bank holiday weekend that will be rainy and rail-disrupted.

The RAC said that around 3.8 million cars would be on the road tomorrow, about 3.2 million on Sunday and around 3.5 million on Bank Holiday Monday.

RAC head of external affairs Pete Williams said: "We're expected this evening's rush hour to be especially busy, with commuter and extra leisure traffic sharing the roads."

Those taking the train this weekend will have to contend with disruption caused by a big programme of Network Rail (NR) engineering work, and a number of major London stations will be affected.

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.

Further north, work around Wolverhampton, Stafford and Crewe will mean amended services for passengers using some 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, which will have a team of 14,000 working on the bank holiday engineering programme, said more than 95% of the network would be unaffected.

It added that the work has been timed to minimise disruption to passengers, as numbers can drop by 20% to 30% over a bank holiday weekend .

NR chief executive Mark Carne said: "Our improvement programme this bank holiday, delivered by a 14,000-strong army of rail workers, is focused on delivering a better service for passengers. We are acutely conscious that many people want to use the railway over the bank holiday to reunite with their friends and families, which is why the vast majority of the network is running normally over the long weekend.

"We'd like to apologise to any passengers whose plans are affected by our improvement work, but I hope they will understand that this is a quieter time on the railway and we want to minimise the overall impact of these vital projects on passengers."

NR was severely criticised for engineering work overruns last Christmas that led to chaotic scenes at Finsbury Park station in north London. A big programme of engineering work over Easter was completed successfully and on time.

While Britain basked in temperatures over 70F (21C) last month, this weekend looks much less promising. Rain is expected to move into southern England tomorrow and Sunday and Monday are likely to be wet.