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.
GE steam turbine locomotives
During test runs, the locomotives displayed excellent acceleration and an ability to maintain schedules better than conventional steam engines, although they also had serious reliability problems and relatively high maintenance costs. On one occasion, the two locomotives failed while hauling a train from Colorado to Omaha, necessitating a 2800-class Pacific steam locomotive to pull them along with the rest of the train for the remainder of the journey. The locomotives worked on several routes in a variety of different capacities, including both passenger and perishable freight service, although they never entered regular revenue service; in June 1939, the railroad returned them to GE in Chicago for what UP president W. M. Jeffers called "necessary modification and/or reconstruction".