It was not the wrong sort of snow, but simply too much of it that appears to have caused the breakdown of five Eurostar and two other trains in the Channel Tunnel. Last night, Eurostar engineers were still trying to discover the precise cause of the incident but the investigation focussed on electrical failures as a result of the change in temperature between the French countryside and the tunnel.
All the trains that broke down were travelling north from France where there was a severe snowstorm. The trains were running slower then normal, 220 km per hour (137 mph) rather than the normal 300 km per hour (186 mph) because of the conditions. While this was necessary to avoid damage from ice thrown up from the track, it meant that the trains were exposed to the snow for even longer than normal.
It is thought that they accumulated vast amounts of snow on the wheel bogies underneath the train which then fell off, taking vital equipment with it. According to one engineer, ‘you can get several tons of snow on one train. If this melts gradually, there is no problem, but if it falls off as one big lump, it can cause serious damage.’ The fact that the trains did not break down until they were well into the tunnel – between 25 kms and 35 kms – gives support to this theory, because it would have taken some time for the large heavy lumps of snow and ice that had accumulated to break away.
Another theory being examined is that it is the accumulation of snow on the front nose cone of the train that causes the problem. Once this melts sufficiently to fall off the train, it is sucked into the electrics, resulting in the failure. According to one expert: ‘this has happened before but not with these devastating consequences. You can get a big accumulation in the nose cone.’
Either way, Eurostar engineers are deeply embarrassed by the failure to the trains which are now 15 years old, about half way through their expected life span, and therefore in need of upgrading. Eurostar trains are among the most technically complicated trains in the world. Although based on French TGV trains built by Alstom, they are far more complex because they have to operate on the electrical systems of the three countries, Belgium, France and Britain, as well as the tunnel, all of which have slightly different characteristics. Moreover, according to Eurostar’s director of engineering, Nicolas Petrovic, the tunnel is a particularly difficult operating environment for the trains:’ It is hot in there, usually 20C and because it is under the sea, it is very salty too which means there are particular challenges’.
The tunnel is the second longest undersea tunnel in the world, and has the greatest stretch under the sea. Two other trains also broke down, a freight train and a Le Shuttle service, suggesting that last night’s conditions were truly exceptional.
Mr Petrovic emphasised that Eurostar do make strenuous preparations for the winter running: ‘We know there are extra difficulties, so we put on snow screens, we change several components and protect electrical sensors.’
Nevertheless, this is the second time in a year that Eurostar trains have been halted by wintry weather. During the cold snap in February, a couple of trains broke down stranding passengers but this was apparently related to power supply difficulties unrelated to the problems on Friday night.
There will be also be question marks over the evacuation procedures and what appears to be a breakdown in communication between Eurostar and Eurotunnel, which is the entirely separate company responsible for the Channel Tunnel. There is a smaller emergency service tunnel between the two train tunnels and evacuating people into it should not pose any problem. However, while fires have resulted in the Le Shuttle services, which carry relatively few passengers being evacuated on several occasions, this is the first time that passengers on Eurostar trains which carry up to 750 people have had to use the escape tunnel.
Normally, Eurostar trains would be towed out by locomotives operated by Eurotunnel, an entirely separate company. However, because so many trains had broken down, this proved impossible and some people escaped through the service tunnel and complained that no instructions or advice had been given to them. People were getting anxious because some of the trains had the power cut off and temperatures were beginning to soar. According to Eurostar sources, once trains are in the tunnel, its management is unable to contact their staff because there is no mobile coverage: ‘It is up to Eurotunnel to arrange the evacuation because they are responsible for safety arrangements in the tunnel’.