Mainline steam trains in Great Britain
The most famous steam locomotive operating on the British main line is the 1923 built "Flying Scotsman". After being taken into public ownership in 2004, following a decade long refit it returned to mainline service in 2016. The fastest steam locomotive ever built, the 1938 built "Mallard", was also certified for main line operation briefly in the 1980s.
High-speed rail
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 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 and , again on standard track. For the first time, 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, that was solved 20 years later by the Zébulon TGV's prototype.