FEW PEOPLE would dispute that the 501 passengers and 16 crew on Eurostar 9047 from Paris to London on June 5 had a lucky escape when their train derailed at around 250 km/h at Croisilles on the TGV Nord line near Arras in northern France. No-one was seriously hurt, but had the train derailed so as to foul the adjacent track, or had it struck a bridge pier like the ICE at Eschede in Germany in June 1998, it may have been another story.

Remarkably, all 20 cars remained upright, although the second bogie of the leading power car and the motored bogie of the adjacent coach came off the rails, as did both bogies of the rear power car. The driver had noted something was amiss shortly before and had already reduced speed before the derailment occurred.

The cause turned out to be the failure of a shaft connecting one of the traction motors to an axle. In contrast to other TGV designs such as the Réseau sets, Eurostars have asynchronous rather than synchronous drives, and this change modified the dynamic stresses on the tripod shaft, requiring a monitoring system to be fitted to detect characteristics that could indicate a failure.

SNCF said this was the first failure of a tripod shaft, but a similar fault led to a Eurostar being taken out of service shortly before entering the British portal of the Channel Tunnel a week earlier; it would appear that in this case the problem was detected before the shaft became detached. SNCF Traction & Rolling Stock Director Roland Bonnepart said that the shaft from the derailed train had been found on the track with some of its fixing bolts missing, suggesting that the root cause may have been a maintenance issue rather than a design fault.

There have been two other instances of TGVs derailing at high speed, and on both occasions the articulated trains remained upright, with no-one on board seriously injured.