The Challenge

On 3 April 2007, the TGV (Train à Grande Vitesse) achieved the current world speed record of 574.8kmph (357.2mph) on the LGV Est high speed line in France, just before the line opened in June 2007.

The goal of the speed trials, which ran for three months culminating in the record, was to investigate and better understand how the different elements of the train, rail and catenary interact at higher speeds. Huge amounts of data were recorded and stored, some of which is still being analysed today.

The ultimate aim is to be able to run high-speed trains faster, while not compromising on safety and without increasing maintenance requirements and costs. The fastest trains in the world currently run in France at 320kmph (198mph). China did run trains at 350kmph (217mph) for a short time but following a crash in July 2011, which investigations blamed on signalling issues, the speed was lowered to 300kmph (186mph).

SYSTRA's Role

This project required collaboration and team-work between all the engineers involved. French national railway company SNCF conducted the trials jointly with Alstom, the train manufacturer, LGV Est owner Réseau Ferré de France (RFF), with engineers from SYSTRA involved in the project management and co-ordination between the companies involved and with outside authorities.

Achieving the record speed, required great precision in every part of the system, from the rolling stock to the track to the catenary. Various modifications were made, including upgrading the power of the train from 9.3MW to 19.6MW, increasing the diameter of its wheels from 920mm to 1092mm, increasing the voltage in the overhead catenary wires from 25kV to 31kV and increasing the tension in the wires from 25kN to 40kN.

The 140km section of the LGV Est where the record was achieved was chosen because of its profile, with a downhill section leading to the place where the highest speeds were reached. The superelevation – or cross slope – of the track on the gentle curves of this section was also increased to contribute to higher speeds.

One of the factors which limited an even higher speed was the speed of the transverse wave induced by the train’s pantograph which connects to the catenary wire. When the speed of the train reaches the speed of this wave, the pantograph loses contact with the wire. The plan had been to attempt 600kmph (372mph) but the speed of the wave was found to be 610kmph which was considered too small a margin.