In 1974 3 generations of electric engines co-existed on the Maurienne line (Chambery - Modane) in the French Alps. The line had 2 distinctive features: it was electrified by 3rd rail, under 1500 V, and it had – still has - steep 3,5% grades. These features required specially dedicated engines. In 1974, the most recent were the CC 6500, built 03-70 to 12-72, 8000 HP. Six CC 7100, 4680 HP, built in 1952-1955, had been assigned to the Maurienne line and equipped with 3rd rail collectors. The oldest motors were the BB 1-80, built in 1924 – 1927, 1300 HP. Those assigned to the Maurienne were called “Unités Maurienne” – Maurienne Units -, and were permanently coupled in duo sets. On this picture, all 3 series get prepared for a light move bound downwards to Saint Jean de Maurienne where they will serve as helpers on the steepest section of the line.