 It was only possible to haul twenty of these heavy locomotives in a single train, and it required several pulling and pushing locomotives on level stretches, while in passing over the Allegheny Mountains west of Altoona, additional helping power was needed.No less than six engines were necessary to move the train around the Horseshoe Curve.Throughout the entire journey, each locomotive was manned by an experienced engineer, who was personally in charge of the locomotive to which he was assigned.