Diesel locomotive Therefore, diesel traction became economical for shunting before it became economical for hauling trains. The construction of diesel shunters began in 1920 in France, in 1925 in Denmark, in 1926 in the Netherlands, and in 1927 in Germany. After few years of testing, hundreds of units were produced within a decade. Diesel-powered or "oil-engined" railcars, generally diesel–mechanical, were developed by various European manufacturers in the 1930s, e.g. by William Beardmore and Company for the Canadian National Railways (the Beardmore Tornado engine was subsequently used in the R101 airship). Some of those series for regional traffic were begun with gasoline motors
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). Diesel locomotives offer significant operating advantages over steam locomotives. They can safely be operated by one person, making them ideal for switching/shunting duties