Will climate change make it necessary to adapt trains to the high temperatures predicted in European latitudes?
The heat wave episodes that hit France this summer underline the importance of reliable air conditioning in TGV and TER trains for passenger comfort.
A maintenance effort should avoid paralysis, at least in the short term, according to the profession.
“
That's a non-topic!
“says Laurent Bouyer, president of Siemens Mobility France.
According to him, the trains are already designed to withstand temperature variations.
The companies are just beginning to take an interest in the question, according to the director of equipment at SNCF Voyageurs, Xavier Ouin.
“
One of the subjects on which we have made progress is the operation of the air conditioning.
We carry out preventive maintenance programs in the spring
", he explains: "
better clean the ducts, better overhaul the compressors, change the filters... In short, avoid all causes of breakdowns
", a fortiori on the trains which have 20 or 30 years old whose air conditioning "
wasn't necessarily crazy
".
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“Fewer outages this year”
The Moroccan TGV, built by Alstom, has air conditioning adapted to an outside temperature of 50°C and a dust filter.
Wikimedia Commons - NicholasNCE
And it works, he says.
“
This year we had a lower breakdown rate than last year when it was much warmer.
But we must be able to do better.
This did not prevent, this summer again, certain trains from breaking down in the middle of the track without electricity... Another idea, according to Xavier Ouin: painting trains white.
"
When it's white, it absorbs less heat than when it's dark, and it's easier to refrigerate inside
," he explains.
On the other hand, the latest materials ordered are not particularly “tropicalised”, as we say in railway jargon, that is to say modified to withstand extreme temperatures.
They will therefore have to hold out until the 2070s... “
We have sold trains in
Norway
and Saudi Arabia.
We know how to do it.
But we deliver what the customers ask us for
,” notes the managing director of the Spanish manufacturer CAF, Javier Martínez Ojinaga, at the major railway show InnoTrans in Berlin.
The Moroccan TGV - built by Alstom - for example has air conditioning adapted to an outside temperature of 50°C and an air filtration system protecting the equipment against dust.
Of course, it's more expensive.
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Slow down the trains
Distribution of bottles of water at Bordeaux Saint-Jean station, June 15, 2022, during the first episode of heat wave of the summer.
Philippe LOPEZ / AFP
"
We have not dimensioned the trains just for the current temperatures, there is always a margin
", assures Bruno Marguet, manager of rolling stock at Alstom.
“
If these trains are well maintained, their current size will allow them to cope without worry.
The exterior railway equipment must withstand temperatures of 55°C, the electronic cards and other interior equipment 70°C, according to equipment manufacturer Thales.
And no changes to these standards are planned for the moment.
It is above all the network which is likely to suffer, indicate all the experts met in Berlin: the rails which expand and the catenaries which fail.
“
Today there is no particular approach aimed at adapting the network
”, indicates in France Olivier Bancel, the director of operations of SNCF Réseau.
And the older the infrastructure, the more fragile it is.
The old catenaries of south-west France, in particular, do not appreciate the heat wave, which forces the SNCF to slow down the trains periodically.
For example, when it is 37 degrees, the temperature of the rail can exceed 55 degrees.
The rail expands and can lead to accidents.
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Paint the rails white
The Al-Haramain high-speed train in Saudi Arabia, connecting Makkah to Madinah, is suitable for running in hot weather.
GIUSEPPE CACACE / AFP
Opinions are divided, in any case, on the relevance of painting the rails white.
A study by the Swiss Federal Institute of Technology in Zurich has shown that when painted in light colours, they are up to 7°C cooler.
“
We don't believe it
,” retorts Oliver Bancel, at SNCF Réseau.
You have to adapt and learn to better anticipate the expansion of the rails and their "buckling" (their deformation), judge Stéphane Féray-Beaumont, head of innovation at Alstom.
Especially since modern railway tracks have long welded rails, since traditional expansion joints - the space between the rails - have been removed for more comfort.
Good design and constant monitoring of the tracks can withstand the heat, says Jafar Oklah, director of infrastructure for Etihad Rail, which is building a network in the Emirates.
“
Above 75°C, we have to slow down the trains
,” he warns, sarcastically.
“
But that never happened!
»
