Railway Reform: Toolkit for Improving Rail Sector Performance - ppiaf

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Railway Reform: Toolkit for Improving Rail Sector Performance 12. Commercial Management Practices And Strategy Development mit trains to operate at track speed until the approach distance to the next controlled siding An ABS signaling system does not prioritize trains—the first train to arrive at the siding where trains will meet is directed to take the siding. To exercise greater control over train movements, railways developed centralized train control systems (CTCs). These systems allow a centralized dispatcher (now sometimes a computer control program) to allow faster trains to pass slower trains moving in the same direction, to allow trains to stay on the main line if they exceed the siding length, or to allow higher priority trains to keep to the main lines with as few stops as possible. The ABS and CTC systems provide several safety advantages. They use electrical track circuits to detect trains and train speeds. These track circuits also detect broken rails or wash-outs and stop trains before passing the danger area. The electronic controls are fail-safe and interlocked so a switch cannot be thrown under a train or allow two train paths to cross. If any part of the system fails, signals automatically protect trains from running into each other. Double track segments are usually directional (up trains on one track, down trains on the other). CTC systems can be designed for reverse running so that trains can use either track to move in either direction, increasing flexibility and capacity, and allowing work crews to perform maintenance on one track while trains move along the other. The CTC systems permit fast trains to pass slow trains, and allow some trains to stop or serve customers on the main line while trains move along the opposite track. In traditional ABS and CTC systems, the railway line is segmented into signal control blocks. Block length is determined by calculating the stopping distance of the heaviest or fastest train—the longest stopping distance—and then fixed by track circuit design. The systems permit trains to occupy a block, and at least one empty block is kept between trains. The number of blocks between trains is determined by how many aspects are used in the signal system. Typically, there are three aspects (for example, red, yellow, green) but systems in the busiest lines can have four or more, which facilitate finer control of speed and allow overlapping blocks so that trains can follow at shorter distances. The latest and most advanced signal systems dispense with wayside signals and discrete signal aspects. Instead, they provide digitally controlled train speed, and base train spacing on the physical characteristics of the infrastructure and particular train, adjusting train speeds to maintain stopping distances between trains. More advanced signal systems provide train ‘pacing’ or speed information that permits the minimum amount of slowing when trains meet, thus reducing energy consumption and maximizing line capacity. Successive advancements in signal and train control systems increase line capacity, safety, and train speeds, and reduce energy consumption. Of course, as systems become more sophisticated, they also become more expensive. The World Bank Page 190
Railway Reform: Toolkit for Improving Rail Sector Performance 12. Commercial Management Practices And Strategy Development Electrification Originally, railway trains were hauled by steam locomotives, fueled with wood, coal, or oil. 122 Diesel-electric and diesel-hydraulic locomotives were developed in response to steam locomotive shortcomings, such as the need for frequent stops to refuel and take on water. As engineering improved, diesel engine technology developed higher horsepower locomotives. Thanks to improvements in wheel-slip controls and computer control systems, modern diesel-electric locomotives are highly productive and energy-efficient. 3kV-DC Overhead Catenary, Georgia To reduce dependence on diesel fuel and provide higher capacity operations, railways turned to electrification, usually using overhead catenary systems to deliver electricity. Electric locomotives can have higher power density—more horsepower or kilowatts per ton of locomotive—which can haul trains at higher speeds and up steeper grades than diesel locomotives. Generally, electric locomotives require fewer maintenance inputs and were once considered more reliable. Modern diesel-electric locomotives are now as reliable as electrics and can provide the similar levels of tractive effort – for high speeds, electric locomotives are advantaged. Electrification is essential for high-speed train operations of more than 160-kph or 100-mph. Electrification is useful in high-density operations where train acceleration is important, such as commuter passenger systems; and where diesel fuel is too expensive or scarce. Electrification is expensive; it requires substations and overhead catenary structures along the railway, and infrastructure maintenance costs are higher. Thus, electrification is rarely financially feasible unless traffic densities are at least 40 million gross tons per year, or for high-speed and commuter services. Electric railways are substantially more environmentally friendly and have fewer carbon emissions than diesel-electric railways if the electricity is generated by renewable energy or nuclear power. If the electricity is generated in a coal-fired plant, electric railways have about the same environmental impact as dieselelectric powered railways. Information systems Information systems are among the most important investments for commercial railways, particularly for revenue, cost accounting, and general ledger systems that have a level of detail that facilitates accurate tracking of railway costs and revenues. Railways must be able to analyze complex data on costs, production statistics, and revenue along several dimensions. Some examples: for passenger services, railways must analyze revenue by ticket type, origin, destination, and time of day; and costs by carriage type, route, time-of-day, and day-of- week; for productivity, railways must analyze number of passengers, passenger kilometers, train kilometers, carriage kilometers. Freight data are equally complex and must include tons, ton-kilometers, disaggregated by commodity, customer, type of 122 There were some early horse-pulled railways. Other early railways were pulled by cables. The World Bank Page 191
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Railway Reform: Toolkit for Improving Rail Sector Performance - ppiaf

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