High-speed rail
h developments

In the early 1950s, the French National Railway started to receive their new powerful CC 7100 electric locomotives, and began to study and evaluate running at higher speeds. In 1954, the CC 7121 hauling a full train achieved a record 243 km/h (151 mph) during a test on standard track. The next year, two specially tuned electric locomotives, the CC 7107 and the prototype BB 9004, broke previous speed records, reaching respectively 320 km/h (200 mph) and 331 km/h (206 mph), again on standard track. For the first time, 300 km/h (190 mph) was surpassed, allowing the idea of higher-speed services to be developed and further engineering studies commenced. Especially, during the 1955 records, a dangerous hunting oscillation, the swaying of the bogies which leads to dynamic instability and potential derailment was discovered. This problem was solved by yaw dampers which enabled safe running at high speeds today. Research was also made about "current harnessing" at high-speed by the pantographs, which was solved 20 years later by the Zébulon TGV 's prototype.
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