Network Rail is urging passengers planning to use the Midland Main Line today (Friday, 26 July) to check before travelling as a reduced service is in operation.

Yesterday (Thursday, 25 July) saw significant disruption on the rail route which links Sheffield to London St Pancras International via the East Midlands and Bedfordshire. Trains had to run at reduced speeds, which also meant a reduced service ran and those which did run were extremely busy.

The railway is made up of 20,000 miles of steel track, which absorbs heat easily. In the summer, the track can get up to 20 degrees hotter than the air temperature. When steel becomes very hot it expands and if there is no room for the rail to expand further, this can cause the rail to buckle. If rails buckle the line has to be closed for repair before trains can run again. Slower trains exert lower forces on the track and reduce the likelihood of buckling.

There were also multiple incidents on the route, including problems with overhead line equipment on the line between Kentish Town and West Hampstead and a fire near the railway in West Hampstead. Network Rail engineers continue to work to resolve these issues, however disruption will continue into today, with a reduced service in place for East Midlands Trains and Thameslink passengers.

Passengers are strongly advised to consider alternative travel arrangements and only travel if their journey is absolutely necessary.

If passengers must travel, they are urged to check before travelling with their train operator or with National Rail Enquiries. Passengers should allow additional time for their journey and take plenty of water with them.

Network Rail would like to thank all those who have been impacted for their patience and apologise for any disruption caused.