20mph speed limits amid heat fears

The rail network has been hit by speed restrictions as low as 20mph amid fears that tracks could buckle in the heat.

Network Rail, responsible for the tracks and signals, ordered a "red alert" and says it is in hourly contact with weather forecasters. More restrictions could be imposed today. Sun reflecting on the tracks makes the temperature of the steel much higher than surrounding air. This can lead to expansion, buckling and the potential for derailment.

A spokesman for Virgin Trains, which operates on the West Coast Main Line and CrossCountry services, said: "Problems have been caused because of these restrictions, which are automatically imposed by NR in very hot weather."

The speed limits caused commuter trains to stack up behind one another throughout the evening peak period.