Why don’t rails get hot in Europe?
The truth is, they do! However, in countries which have been traditionally hotter than ours, rails are stressed to be able to withstand higher temperatures.
Rails in the UK are stressed to 27 degrees, the UK mean summer rail temperature. The rail can withstand some degree of change in temperature either side of this. However, when the air temperature is 30 degrees, the temperature on the rail can actually be up to 20 degrees higher, exceeding the maximum temperature our rails are designed to cope with.
The problem is that when steel rails get hot, they expand and this can cause a type of signalling problem called a track circuit failure and in extreme cases can cause a buckled rail.
If a rail buckles then the train service will not be able to run at all until the buckled rail is replaced with a new one.
When Network Rail assesses that the temperature of the rails is going to exceed what it is designed to cope with they put speed restrictions in place to help prevent buckled rails.
A train going over a hot rail at a slower speed exerts less pressure on the rail and will help to prevent it buckling. Because overhead power lines also expand in the heat and sag, it also prevents the train’s pantograph from pulling the sagging wires down.
It means have trains have to run more slowly, and there will be fewer trains as a result, but this is better than causing a bigger problem and then being unable to run any trains at all.
So why don’t we replace all our rails with ones stressed for higher temperatures?
The UK, and particularly East Anglia, is seeing hotter summers these days so this may seem like the obvious solution. The problem is that if UK rails were stressed to the same degree as those in very hot countries, there would be the risk of rails fracturing when the rails contract as the temperature drops in winter.
However, one solution that is helping to keep the track cool is to paint it white.
Network Rail paints rails white at critical points so they absorb less heat, which reduces expansion.
Typically, a rail painted white is 5°C to 10°C cooler than one left unpainted. You can see an example of this at Colchester North station this year where a set of points (a moveable section of track which allows trains to move from one line to another) has been painted white.
Please check before you travel
Greater Anglia would like to apologise for the inconvenience caused by heat-related speed restrictions. While they are in place, please check how trains are running before you travel at www.greateranglia.co.uk.
Where possible, we will try to make you aware in advance of any predicted timetable changes due to hot weather.
There will be extra staff at stations giving out water to any customers caught up in any disruption and we will be doing everything we can to get passengers from a to b reliably and in comfort.
Look out for our new water fountains which are being installed at some stations to help keep you hydrated while travelling. You can also claim a free refillable water bottle to help us reduce the use of single-use plastic bottles.
Our fleet maintenance teams will be doing everything they can to ensure that the air con on our trains is in working order. However, if you do board a train that feels uncomfortably warm please report it on twitter to @greateranglia and let us know which service you are travelling on and the carriage number if you know it (it’s inside the carriage, above the doors). We can then arrange for repairs to be carried out, sometimes by using a mobile engineer who can board the train to try and fix the problem whilst it is in service, or by scheduling it to visit a depot overnight.
Network Rail’s planned programme of engineering works, including the renewal of overhead lines and new rails will help to make the railway more able to cope with hotter temperatures in the future.
An explanation of what happens when rails get hot can be viewed here: https://www.networkrail.co.uk/running-the-railway/looking-after-the-rail...