Britain’s railways are “simply not engineered” to cope with next week’s heatwave, experts have warned, amid fears temperatures could reach 40C.
Rail firms have advised passengers against travelling and said that delays and cancellations were likely, with one company halving its services to London.
Trains will limit their speeds over fears that tracks will buckle under the extreme temperatures, meaning journeys that go ahead are expected to be “significantly longer”.
The Met Office has issued its first-ever red heat warning this week for much of England, including London, for Monday and Tuesday.
Network Rail route director Gary Walsh said: “The railway in this country is simply not engineered to run normally in such extreme temperatures.
“We’ve got extra teams out around the route, ready to respond to any incidents, but with temperatures set to break all records, we need to also reduce the speed at which trains can run.
“This reduces the risk of tracks buckling in the heat and also means that when the overhead line expands it won’t get tangled on passing trains.”
20,000 miles of track
Network Rail, which operates 20,000 miles of track across the UK, advised people in England and Wales to only travel “where necessary” and said that journeys would take “considerably more time”.
Passengers should wear cool clothes, bring handheld fans and pack a water bottle, it added.
East Midlands Railway has slashed its timetable for London, where temperatures are expected to peak next week.
Only one train per hour – compared to the normal two – will run between the capital and Sheffield, Nottingham and Corby.
Transport for London has not provided advice to commuters, but mayor Sadiq Khan said the “dangerous” levels of heat would probably have “an impact on travel”.
Temperatures are forecast to be less extreme in Scotland, although the Met Office has issued an amber heat warning for southern parts of the country.
The TransPennine Express, which runs between the North of England and Scotland, said that journeys would “take longer than usual” and warned of further disruption.
Network Rail asked customers in Scotland to check their trains before travelling and to take “sensible precautions”.
Related: No 10 won’t say if Johnson will join Cobra heatwave meeting as he ‘prepares for Chequers party’