Three weeks of severe disruption to rail services has begun at the UK's busiest station.


Nearly half of London Waterloo's platforms are closed from today until August 28 to enable a major engineering project to take place.


There is a significant reduction in South West Trains services from popular commuter locations such as Woking, Guildford and Surbiton.
Some stations are closed and others will be much busier than normal.


An average of 270,000 journeys are normally made to or from Waterloo every day.


The project to extend the station's platforms will allow longer trains to operate on suburban routes from December.


To ease some of the impact of the work the old Eurostar platforms are being used at Waterloo for the first time since the cross-Channel train service relocated to London St Pancras in 2007.


Rail chiefs urged passengers to consider taking a holiday, working from home or travelling earlier or later than normal while the project is under way.


Network Rail chief executive Mark Carne has previously admitted he is "worried there will be challenging days" and accepted that "there are going to be days when the service is very difficult for people".


First Group and Hong Kong-based MTR will take over the South West Trains franchise from Stagecoach on August 20.


The Waterloo work will culminate over the August bank holiday weekend, when it will be one of a number of large projects being carried out.


Passengers hoping to take a leisure trip on the final public holiday before Christmas will find major changes to services out of London Bridge, London Euston, London Liverpool Street and London Paddington, as well as Waterloo.


The work at Euston will be one of the first major physical projects in preparation for the HS2 high-speed railway, as a new power supply is installed at the station.


Network Rail will hand out free ice cream at London Victoria, London Bridge and Euston next week as part of a promotional campaign to remind people to plan their journeys in advance.


It said it carries out major engineering work on bank holidays as up to 50% fewer passengers use the railway during those periods.