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.
Diesel locomotive
As diesel locomotives advanced, the cost of manufacturing and operating them dropped, and they became cheaper to own and operate than steam locomotives. In North America, steam locomotives were custom-made for specific railway routes, so economies of scale were difficult to achieve. Though more complex to produce with exacting manufacturing tolerances ( for diesel, compared with for steam), diesel locomotive parts were easier to mass produce. Baldwin Locomotive Works offered almost five hundred steam models in its heyday, while EMD offered fewer than ten diesel varieties.. In the United Kingdom, British Railways built steam locomotives to standard designs from 1951 onwards. These included standard, interchangeable parts, and were cheaper to produce than the diesel locomotives then available. The capital cost per drawbar horse power was £13 6s (steam), £65 (diesel), £69 7s (turbine) and £17 13s (electric).