Wrong kind of heatwave as trains are delayed

The swing bridge was moved to allow river traffic through, but when staff tried to put in back in place they couldn’t and it was not aligned.

Video: Your last chance to bake in the sun before thunderstorms arrive

The track closed at 10.50am causing delays of up to 60 minutes but it was reopened by 1.30pm.

A Network Rail spokeswoman said: “The rails on the swing bridge have expanded in the heat but it has been fixed and trains through the station are now able to run.”

Speed limits are also in place on some lines due to high rail temperatures.

On the Ilkley line from Leeds and Bradford, a signalling faulty caused delays of up to half an hour this afternoon.

Great Western services were affected to and from London Paddington, with track temperatures reaching almost 50C (122F).

A number of Southeastern lines suffered from the temporary speed limits, including those between Lewisham and Blackheath, south-east London, Whitstable and Faversham, Kent and Hastings and Crowhurst, East Sussex.

Restrictions were also implemented on the route between Sheffield and Manchester Piccadilly.

Network Rail said rails can reach up to 20C higher than air conditions in direct sunlight on warm days.

They are made of steel and expand as they heat up and are subjected to strong compression. Speed restrictions are introduced in a bid to manage the expansion of the track by lowering the forces exerted on it.

If rails do buckle, lines must be closed and track repaired before services can resume. But this work cannot be carried out until the temperature has dropped, leading to severe disruption.

A spokesman for Network Rail said: “Our modern rails are far more resistant to heat expansion and buckling than they used to be.

“However, a day this hot affects even our track, so we need to restrict speeds for safety.”

A restriction of 20mph was imposed at 12pm on the three-mile section between Paddington and Old Oak Common.

NR said it would be lifted when the rails have cooled sufficiently.

Separately, a broken down train between York and Doncaster this evening was causing cancellations and delays of up to 45 minutes.