Electrification of railways

Physical Characteristics of Steam, Oil-Electric, and Electric, Rail Tractors. The principal competitors of the electric tractor are the steam locomotive and the oil-electric tractor. The physical limitations and performance of these tractors are compared, and it is shown that the limited output and poor weight efficiency of the steam and oil-electric tractors offer serious handicaps in competition with electric traction. Economic Aspects of Electrification. (a) To take advantage of the superior performance of electric tractors entails large capital expenditures for track equipment and substations. An approximate equation is deduced showing that there is a permissible economic capital expenditure for electrification, in pence per ton-mile carried per annum. (b) To determine whether a railway can be equipped for electric working at a cost not exceeding this economic maximum, a hypothetical example for handling varying tonnages of goods traffic is tabulated, the costs of equipping the track for electric working are given, and the annual operating costs are compared with those for steam haulage. This demonstrates the economic feasibility of railway electrification where the traffic density is fairly high. Appendix. An appendix is added in which the physical and economic characteristics of the distribution circuits of an electric railway are discussed. It is shown that, from an economic standpoint, the single-phase system shows attractive possibilities.