Network Rail engineers will carry out additional track inspections to check for heat-related problems while at some locations special remote monitoring equipment has been deployed to help spot rails which are becoming too hot.
Our engineers have also been preparing in advance – stressing sections of track (artificially stretching the rails) in known hot-spot areas to help them cope with sudden rises in temperature and painting rails white at key locations to help reflect the sun and keep them up to 10°C cooler.
During sustained hot spells, rails in direct sunshine can be as much as 20°C hotter than air temperature and expand as they get warmer – sometimes causing them to curve or buckle.
If rail temperatures in an area do rise significantly, localised speed restrictions may be put in place in some locations to slow trains down and reduce the amount of force being placed on the rails.
High temperatures can also affect overhead power lines, causing the metal wires to expand and sag meaning trains have to slow down when travelling beneath them.
Liam Sumpter, Chief Operating Officer for Network Rail Scotland, said: “Hot weather can create real challenges for the railway causing rails to expand and buckle, overhead lines to sag and surrounding land to dry out making our tracks more susceptible to flooding.
“Every year we invest millions across the country to prepare Scotland’s Railway for summer and to keep our passengers on the move.
“Our engineers will be out on the network in the coming days, monitoring rail temperatures and working hard to make sure we manage any potential issues.”
How we prevent tracks from getting too hot:
- We work closely with specialist weather forecasters to assess where the tracks will be hottest.
- Our teams check track stability each winter as part of ongoing maintenance and strengthen any weak parts before summer.
- We paint certain parts of the rail white so they absorb less heat – and expand less. Typically, a rail painted white is 5°C to 10°C cooler than one left unpainted.
- As most track is made up of long pieces of rail that are stretched and welded together, there is much less chance of buckling in very high temperatures.
- When a track is made up from short rails bolted together, we leave small gaps between each one so that expansion doesn’t cause a problem.
- We’re always improving how we measure and calculate rail temperatures. One way we’re doing this is by installing probes that alert us when track temperatures rise to give us chance to take action and stop a problem before it happens.
- In some parts of the network, tracks are laid on reinforced concrete slabs rather than on sleepers and ballast (the bed of stones that supports the sleepers). This helps to prevent rails from buckling.