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.
Dieselisation
In rail transport, dieselisation refers to the replacement of the steam locomotive or electric locomotive with the diesel-electric locomotive (often referred to as a "diesel locomotive"), a process which began in the 1930s and is now substantially complete around the world.
The replacement of either steam or diesel haulage with electric locomotives is known as electrification. Whereas the benefit of replacing steam traction is indisputable, there is some dispute as to whether it is best replaced by dieselisation or electrification. Electrification has a high initial capital cost but the operating costs are lower. The overall savings depend on the effect of the investment cost compared with the savings due to lower operational and maintenance costs and the influence of better acceleration and tractive effort on railroad throughput. These are obviously different for e.g. urban networks and very long-distance networks with low frequencies. However, many railway commentators are increasingly suggesting that the ability of railways to operate with electricity not produced from fossil fuels may offer a decisive advantage over diesel power.