South West Trains and Network Rail have imposed a number of speed restrictions on the tracks between Clapham Junction and London Waterloo between 12:00 and 18:00 today on account of the hot weather.
A spokesperson for the South West Trains-Network Rail Alliance said:
Very hot weather can cause an impact on the service we can provide. As with all metals, the track we use to run our trains on expands and contracts depending on its temperature, i.e. the hotter it gets, the more it expands. Just like a car on a warm day, the metal can reach temperatures far in excess of the surrounding air temperature.
A number of other services will be affected (full details can be seen here), with a number of trains not stopping at Vauxhall on the way to London Waterloo, with Network Rail advising commuters on these services to travel to Waterloo and double back.
Over the weekend, temperatures on the tracks reached nearly 50 degrees centigrade. Despite preparation work for hot weather, the "ageing condition of the infrastructure" means that speed restrictions have been put in place at some locations. Changes will include extended journey times, with some trains not able to call at all stations and a reduction in the overall number of services provided. Full details of service alterations can be seen here.
We apologise for the impact this will have on our customers this afternoon. We will continue to closely monitor the rail temperature over the coming hours and days and will keep our passengers up to date with the latest service information through our website, twitter, information at stations, announcements on trains and through National Rail Enquiries.