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Network Rail introduce speed restrictions, as track temperatures soar

Waterloo Sunset.

With temperatures expected to soar this week, Network Rail has activated its extreme weather action teams (EWATs) across the country to ensure passengers are kept safe and the railway keeps running as reliably as possible.

The national rail body say that most of the railway operates normally in hot weather, but speed restrictions may be introduced at the hottest locations, where track temperatures are set to hit 50 degrees centigrade. 

The company say the network is made of 20,000 miles of steel track, which absorbs heat easily. In the summer though, 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.

Since the last hottest summer in 2003, in 2018, Network Rail say they have reduced the number of buckled rail incidents by 83%. They explained that:

  • When installing their steel rails, they use a process called stressing to protect against buckling. 
  • Stressing the rails allows them to set the range of temperatures the track can comfortably cope with. 
  • Stressing the rails to cope with higher summer temperatures would mean making them less able to cope with low temperatures during the winter. 
  • The rails have a stress-free temperature of 27oC, the average summer rail temperature in the UK. 

Long periods without rain can mean the ground underneath the tracks dries out and shrinks, creating pothole-like cracks. Much like on the roads, trains can’t drive at full speed over these defects and have to slow down to keep passengers safe. 

Network Rail say they have a number of measures in place to reduce the impact of hot weather on the railway, but that speed restrictions may have to introduced during the hottest part of the day at vulnerable locations, as slower trains exert lower forces on the track and reduce the likelihood of buckling.

Nick King, network services director at Network Rail, said: “Keeping passengers safe and moving are our top priorities during this heatwave. That’s why we sometimes have to put speed restriction on to prevent our rails, that can be over 20 degrees hotter than air temperatures, from buckling which can derail a train and cause huge delays.”