Dieselisation
Dieselisation took place largely because of the tremendous reduction in operating costs it allowed. Steam locomotives require large pools of labour to clean, load, maintain and run. They also require extensive service, coaling and watering facilities. This was their biggest inferior measure as compared to the diesel locomotive in the number of ton-miles or passenger traffic miles either could run. Diesels could and did have a significantly higher initial price per unit-horsepower delivered. However, their far greater range between fueling stops, the absence of water stops, and the much higher unit availability between inspection repair and maintenance stops, were far better than steam. Diesels simply required significantly less time and labour to operate and maintain. Diesel power was also more scalable to power requirements, owing to the control systems that allowed multiple units to be controlled by one operator. "Double header" steam power required a crew for each locomotive. Initially, diesel locomotives were less powerful than the typical steam locomotives. Between the late 1930s and the late 1950s the power available with diesel locomotive engines roughly doubled, although the most powerful steam locomotives ever built still exceeded the power of the most powerful diesel locomotives from the late Twentieth Century.
Steele v. Louisville &amp; Nashville Railway Co.
The diesel-electric locomotive assaulted the primacy of the coal/oil fired steam locomotive from every angle. First, it had a much higher duty cycle than any steam locomotive could match. Famously, the use of steam locomotives to attempt the achievement of the schedules for the crack passenger trains between Chicago and the West Coast, required no less than nine (9) complete changes of engine and tender between Chicago and Los Angeles/San Francisco. With no steam engine/tender set travelling more than 250 miles. Diesels would complete these long distance runs with the same motive power units. And the diesel units would only receive fuel and water at limited operating stops. So the number of in-cab crews necessary to operate any schedule would be dramatically reduced by the introduction of diesels