Instruct: Given a question, retrieve relevant documents that answer the question.
Query: Are steam locomotives more powerful than diesel?
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.
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 
The first trains were rope-hauled, gravity powered or pulled by horses, but from the early 19th century almost all trains were powered by steam locomotives. From the 1910s onwards, steam locomotives began to be replaced with less labor-intensive (and cleaner) diesel and electric locomotives, although these new forms of propulsion were far more complex and expensive than steam power. At about the same time, self-propelled multiple unit vehicles (both diesel and electric) became much more widely used in passenger service. Dieselisation of locomotives in day-to-day use was completed in most countries by the 1970s. Steam locomotives are still used in heritage railways which are operated in many countries for the leisure and enthusiast market.
Dieselization got a boost in the early 1930s from three factors: the development by General Motors and its Winton Engine Corporation subsidiary of diesel engines with vastly improved power-to-weight ratios and output flexibility; the desire of railways to find more cost-efficient locomotion for passenger service at the height of the Great Depression; and design innovations in rail equipment that reduced weight, making the contemporary diesel engines, which were low-powered by today's standards, viable for mainline passenger service. The mid-1930s saw the introduction of lightweight diesel-powered streamlined trainsets such as the Burlington Route's Zephyrs and Union Pacific's M-1000x "City" trains, which were diesel's first assault against the dominance of steam in mainline passenger service. During the second half of the decade, diesel locomotives with sufficient power for full-size passenger trains were developed and put into regular production. Improved GM diesel engines in 1938 increased power and reliability. Dieselization of passenger service gained momentum as the decade drew to a close and the first model of mainline diesel freight locomotive was on the market in 1940. Dieselization was especially attractive to western railroads, for whom the watering requirements of steam locomotives were a problem in vast stretches of the western interior. Coal-country railroads were generally reluctant to embrace diesel, a competitor to one of their main hauling markets, well into the 1940s.
In the 1940s, diesel locomotives began to displace steam power on American railroads. Following the end of World War II, diesel power began to appear on railroads in many countries. The significantly better economics of diesel operation triggered a dash to diesel power, a process known as Dieselization. By the late 1990s, only heritage railways continued to operate steam locomotives.
In 1906, Rudolf Diesel, Adolf Klose and the steam and diesel engine manufacturer Gebrüder Sulzer founded Diesel-Sulzer-Klose GmbH to manufacture diesel-powered locomotives. The Prussian State Railways ordered a diesel locomotive from the company in 1909. The world's first diesel-powered locomotive (a diesel-mechanical locomotive) was operated in the summer of 1912 on the Winterthur–Romanshorn railway in Switzerland, but was not a commercial success. The locomotive weight was 95 tonnes and the power was 883 kW with a maximum speed of 100 km/h. Small numbers of prototype diesel locomotives were produced in a number of countries through the mid-1920s.
Although diesel locomotives generally emit less sulphur dioxide, a major pollutant to the environment, and greenhouse gases than steam locomotives, they are not completely clean in that respect. Furthermore, like other diesel powered vehicles, they emit nitrogen oxides and fine particles, which are a risk to public health. In fact, in this last respect diesel locomotives may perform worse than steam locomotives.
The first regular use of diesel–electric locomotives was in switching (shunter) applications, which were more forgiving than mainline applications of the limitations of contemporary diesel technology and where the idling economy of diesel relative to steam would be most beneficial. GE entered a collaboration with the American Locomotive Company (ALCO) and Ingersoll-Rand (the "AGEIR" consortium) in 1924 to produce a prototype "boxcab" locomotive delivered in July 1925. This locomotive demonstrated that the diesel–electric power unit could provide many of the benefits of an electric locomotive without the railroad having to bear the sizeable expense of electrification. The unit successfully demonstrated, in switching and local freight and passenger service, on ten railroads and three industrial lines. Westinghouse Electric and Baldwin collaborated to build switching locomotives starting in 1929. However, the Great Depression curtailed demand for Westinghouse's electrical equipment, and they stopped building locomotives internally, opting to supply electrical parts instead.
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).
Two significant construction errors were discovered during restoration:These errors were corrected and the opportunity taken to incorporate some other improvements, including the previously recommended Kylchap exhaust system, which has finally unlocked the locomotive's true potential as a powerful express passenger locomotive. When the "Duke" was first allowed to haul a full load on the main line, it became immediately obvious that the boiler was now producing steam at a more efficient rate and that the reborn "Duke" was unrecognisable from the failure that was experienced under British Railways ownership With these modifications, the "Duke" is now one of the most powerful steam locomotives ever to run on Britain's railways, past or present (the LMS Coronation Class Pacifics held that title under British Railways auspices - the three cylinder "Duke" never actually achieved the 3000 cylinder horse power figure that was recorded by the four cylinder Princess Coronation Class); ironically, it is now more powerful than not only the English Electric Type 4 diesel locomotives which replaced it directly in service, but also the type 4 and 5 diesel locomotives built to replace the earlier diesels.
The reciprocating mechanism on the driving wheels of a two-cylinder single expansion steam locomotive tended to pound the rails (see hammer blow), thus requiring more maintenance. Raising steam from coal took a matter of hours, and created serious pollution problems. Coal-burning locomotives required fire cleaning and ash removal between turns of duty.[73] Diesel or electric locomotives, by comparison, drew benefit from new custom-built servicing facilities. The smoke from steam locomotives was also deemed objectionable; the first electric and diesel locomotives were developed in response to smoke abatement requirements,[74] although this did not take into account the high level of less-visible pollution in diesel exhaust smoke, especially when idling. In some countries, however, power for electric locomotives is derived from steam generated in power stations, which are often run by coal.
The steam locomotive remained by far the most common type of locomotive until after World War II. 
Steam locomotives are less efficient than modern diesel and electric locomotives, and a significantly larger workforce is required to operate and service them. British Rail figures showed that the cost of crewing and fuelling a steam locomotive was about two and a half times larger than the cost of supporting an equivalent diesel locomotive, and the daily mileage they could run was lower.. Between about 1950 and 1970, the majority of steam locomotives were retired from commercial service and replaced with electric and diesel-electric locomotives. While North America transitioned from steam during the 1950s, and continental Europe by the 1970s, in other parts of the world, the transition happened later. Steam was a familiar technology that used widely-available fuels and in low-wage economies did not suffer as wide a cost disparity. It continued to be used in many countries until the end of the 20th century. By the end of the 20th century, almost the only steam power remaining in regular use around the world was on heritage railways.
The maintenance and operational costs of steam locomotives were much higher than diesels. Annual maintenance costs for steam locomotives accounted for 25% of the initial purchase price. Spare parts were cast from wooden masters for specific locomotives. The sheer number of unique steam locomotives meant that there was no feasible way for spare-part inventories to be maintained. With diesel locomotives spare parts could be mass-produced and held in stock ready for use and many parts and sub-assemblies could be standardized across an operator's fleet using different models of locomotive from the same builder. Modern diesel locomotives are designed to allow the power assemblies to be replaced, which greatly reduces the time that a locomotive is out of revenue-generating service when it requires maintenance.
Stone Mountain originally had three steam locomotives, the "General II," "Texas II," and "Yonah II." The SMRR named the engines after the famous engines of The Great Locomotive Chase, and were given nineteenth century style smokestacks and headlights. Despite these modifications, the engines, having been built between 1919 and 1927, still have noticeably modern appearances, with larger proportions than their ancestors and have more advanced cylinders, valve gear, and other modern applications. While steam engines ceased running in the 1980s, they continued to "pull" trains for some time. In these instances, one of the steam engines was coupled in front of a diesel which, while disguised as a baggage car or auxiliary tender, would push the engine. The diesel's controls were placed in the cab of the engine and air piped from the diesel's main reservoir to allow the steam engine's whistle to sound. Aside from the whistle, the steam locomotive remained inactive, with the diesel being the train's sole motive power.
The introduction of electric locomotives around the turn of the 20th century and later diesel-electric locomotives spelled the beginning of a decline in the use of steam locomotives, although it was some time before they were phased out of general use.[69] As diesel power (especially with electric transmission) became more reliable in the 1930s, it gained a foothold in North America.[70] The full transition away from steam power in North America took place during the 1950s. In continental Europe, large-scale electrification had replaced steam power by the 1970s. Steam was a familiar technology, adapted well to local facilities, and also consumed a wide variety of fuels; this led to its continued use in many countries until the end of the 20th century.
Competition from diesel spurred a round of development in steam locomotive technology. High style, high speed "steamliners" produced during the second half of the 1930s became the speed kings of passenger service. Duplex and articulated steam locomotives built in the early 1940s exceeded the power of any diesel ever built, although their power was edged by gas turbine-electric locomotives during the 1950s. But the limits of steam technology were rapidly being reached. The new locomotives were mechanically complex and extremely specialized. Locomotive size became an issue, as steam engines became so big in the 1940s that the cylinder and boiler dimensions were pushing the limits that the loading gauge would allow. Fireboxes became so big that firing a steam locomotive became an extremely difficult job without the aid of mechanical stokers. Mechanical stokers for feeding coal to locomotives were in use in the 1920s.[7] Steam turbine-electric locomotive power was developed in 1938 by General Electric. GE abandoned the project in 1943 after results were unsatisfactory during trials with three railroads, however, Baldwin Locomotive Works built three steam turbine-electric locomotives in 1948. They were expensive to operate and insufficiently reliable for their intended service, and were scrapped in 1950. Baldwin's steam turbine-electric program resulted in one more locomotive in 1954, which was also not successful in service.
Steam-diesel hybrid locomotives can use steam generated from a boiler or diesel to power a piston engine. The "Cristiani Compressed Steam System" used a diesel engine to power a compressor to drive and recirculate steam produced by a boiler; effectively using steam as the power transmission medium, with the diesel engine being the prime mover
Union Pacific had long sought the biggest and best locomotives. In the 1930s, a pair of steam turbine locomotives were tried but rejected. Before World War II, Union Pacific had been adding diesels to its roster, but none pulled road freight trains. The idea of using four diesels to equal the power of a steam locomotive was unappealing, so the search began for something bigger. General Electric had been building gas turbines for aircraft and proposed using something similar on a locomotive. Union Pacific thought maintenance costs for a locomotive were largely independent of its power, so a smaller number of more powerful locomotives would save money.
Weighing against the cost of, and inertia against, replacing the large investment that railroads had in existing steam power were the dramatic increases in flexibility and efficiency with diesel. The fastest and most powerful steam locomotives were faster and more powerful than diesels; however, their range of efficient operation was severely limited. Diesels pro-rate their fuel usage to the length of trains, which a steam engine cannot do. Multiple-unit diesel power is scalable to power requirements with one locomotive crew; steam power is not. A high speed Hudson steam locomotive is good for only one situation, high speeds on level grades. The diesel locomotive can be operated by a single person, with no need of a fireman to run the boiler (two person cab crews may be required for other reasons). Also, diesels use much less fuel and no manpower when idling, something locomotives often do. Diesels can be parked running for days unattended, whereas steam engines must be constantly tended to if not completely shut down. Bringing a steam engine boiler up to operating temperature is often regarded as both an art and science, requiring much training and experience. A diesel is much simpler to start and shut down.
The 21 steam locomotives owned by the PRSL were from the PRR subsidiary WJ&S. They all consisted of PRR classes. Before dieselization the PRSL was more apt to lease its motive power from either of its parent railroads as it completely lacked any heavy passenger locomotives (like 4-6-2 Pacifics). As its parent railroads began to replace steam with diesel locomotives, the PRSL became a haven for steam locomotives during their final years of operation.
In comparison to the principal alternative, the diesel engine, electric railways offer substantially better energy efficiency, lower emissions and lower operating costs. Electric locomotives are also usually quieter, more powerful, and more responsive and reliable than diesels. 
They have no local emissions, an important advantage in tunnels and urban areas. Some electric traction systems provide regenerative braking that turns the train's kinetic energy back into electricity and returns it to the supply system to be used by other trains or the general utility grid. While diesel locomotives burn petroleum, electricity can be generated from diverse sources including renewable energy.Steam-diesel hybrid locomotives can use steam generated from a boiler or diesel to power a piston engine. The "Cristiani Compressed Steam System" used a diesel engine to power a compressor to drive and recirculate steam produced by a boiler; effectively using steam as the power transmission medium, with the diesel engine being the prime mover
The first costs were much in favour of steam locomotives, for which it decreased in cost per unit of power as the size increased, an advantage that the diesel-electric did not seem to have. Large diesel-electric locomotives of more than were usually three to four times greater in first cost than steam locomotives of equal power. In addition, unless it was supercharged, a diesel lost 3% of its rated power output with every increase of in altitude.
Three locomotives were ordered by the Steel Company of Wales (SCOW) for their Abbey, Margam and Port Talbot works during the early 1950s, to replace the elderly locomotives which were running at that time. The Steel Company of Wales wanted to see how steam locomotives compared against diesel locomotives, but because the elderly steam locos that they had at that time, did not give a modern and fair view on steam locomotives, they ordered large and specially designed tank locomotives from W.G Bagnall, who had provided 2 powerful 0-4-0ST locomotives to Port Talbot in the 1930s. SCOW were testing to see whether steam or diesel was more economical and also to see which motive power was better on the duties at the steelworks. 
As diesel shunters began to appear in ever-increasing numbers, attempts were made by companies such as Sentinel to adapt the vertical boilers from their steam powered road vehicles for use in shunting locomotives, in order to compete with the newcomers. Although these were found to be equal in power and efficiency to most of the early diesel designs, their development came too late to have any real impact. Outwardly, they bear more resemblance to diesels than steam locomotives. A number have been preserved on heritage railways, although few of these are in working order, being designed very specifically for shunting work and lacking the necessary speed to travel any kind of distance.
Diesel locomotives offer significant operating advantages over steam locomotives. They can safely be operated by one person, making them ideal for switching/shunting duties in yards (although for safety reasons many main-line diesel locomotives continue to have 2-man crews: an engineer and a conductor/switchman) and the operating environment is much more attractive, being quieter, fully weatherproof and without the dirt and heat that is an inevitable part of operating a steam locomotive. Diesel locomotives can be worked in multiple with a single crew controlling multiple locomotives in a single train — something not practical with steam locomotives. This brought greater efficiencies to the operator, as individual locomotives could be relatively low-powered for use as a single unit on light duties but marshaled together to provide the power needed on a heavy train. With steam traction a single very powerful and expensive locomotive was required for the heaviest trains or the operator resorted to double heading with multiple locomotives and crews, a method which was also expensive and brought with it its own operating difficulties.