The UK is currently experiencing extreme weather conditions, with the country set to see record-breaking temperatures today (19th July 2022). Quadrant Transport investigates how high temperatures can have an impact on rail infrastructure.
A red extreme heat warning has been issued by the Met Office in England, with amber warnings in Scotland and Wales. Hot weather can cause problems and disruption to railways, with UK rail tracks having a stress-free temperature of 27 degrees.
When the air temperature reaches 30 degrees, the temperature on the rail can be up to 20 degrees higher. When steel rails get hot, they expand, and this could cause a buckled rail.
Rail Tracks Can Buckle Even With Preventions In Place
On the railway track, the steel rail is a long piece of metal that can expand or contract significantly in the summer and winter. This generates forces that try to push and pull the railway out of shape. To prevent the track from buckling, the mass of the sleepers and ballast are designed to contain these forces.
Remote monitoring systems can tell networks that a section of a track might be expanding too much and could cause problems. From this, local speed restrictions are introduced as slower trains cause lower forces on the track and can reduce the chance of buckling.
However, rails sometimes buckle even with preventions in place, and that means that the track needs to be closed and repaired before the track can run again. This can disrupt journeys because often, networks must wait until the rail temperature has dropped before essential repairs can be carried out.
How Can Tracks Be Prevented From Getting Too Hot?
Network Rail is aiming to prevent the tracks from getting too hot in these recording-breaking temperatures that the UK is currently facing.
Working closely with specialist weather forecasters and local weather stations, the network can make necessary plans and actions so that the rails are less likely to buckle.
Its teams check the track stability each winter as part of ongoing maintenance, and they can strengthen weak parts before the summer.
When it comes to the summer, certain parts of the rail can be painted white so that they absorb less heat. Typically, a rail painted white is 5°C to 10°C cooler than one left unpainted.
So that an expansion will not cause a problem, when a track is made up of short rails bolted together, small gaps are left between each one.
In order to calculate rail temperatures, probes are being installed that alert Network Rail when track temperatures rise to give the network the chance to act on and stop a problem before it happens.
It is essential that the rail industry acts on preventing rail tracks from becoming too hot so that disruptions and problems are minimal, with the safety of passengers at the centre of network plans.