Operation V150, where 150 again refers to a target speed in metres per second, was a series of high speed trials carried out on the LGV Est prior to its June 2007 opening. The trials were conducted jointly by SNCF, TGV builder Alstom, and LGV Est owner Réseau Ferré de France. Following a series of increasingly high speed runs, the official speed record attempt took place on 3 April 2007. The top speed of 574.8 km/h (159.6 m/s, 357.2 mph) was reached at kilometer point 191 near the village of Le Chemin, between the Meuse and Champagne-Ardenne TGV stations, where the most favorable profile exists.
I watched this online, on a not very good quality streaming video, but it was still impressive. It was only while reading the Wikipedia page I realised that this train was going at a significant proportion of the speed of sound. It was the “150 metres a minute” thing that did it.
I don’t think we’ll ever see 600kph service trains ever; the energy and safety implications are just too high. However it’s nice to see the French continuing the grand tradition of insane railway speed record attempts.