The Story of Electricity

by John Munro

CHAPTER XII.

ELECTRIC RAILWAYS.

The electric railway of Dr. Werner von Siemens constructed at Berlin in 1879 was the forerunner of a number of systems which have had the effect of changing materially the problems of transportation in all parts of the world. The electric railway not only was found suitable as a substitute for the tramway with its horse-drawn car, but far more economical than the cable cars, which were installed to meet the transportation problems of large cities with heavy traffic, or, as in the case of certain cities on the Pacific slope, where heavy grades made transportation a serious problem. Furthermore, the electric railway was found serviceable for rural lines where small steam engines or "dummies" were operated with limited success, and then only under exceptional conditions. As a result, practically every country of the world where the density of population and the state of civilization has warranted, is traversed by a network of electric railways, securing the most complete intercommunication between the various localities and handling local transportation in a manner impossible for a railway line employing steam locomotives.

The great advance in electric transportation, aside from its meeting an economic need, has been due to the development of systems of generating and transmitting power economically over long distances. If water power is available, turbines and electric generators can be installed and power produced and transmitted over long distances, as, for example, from Niagara Falls to Buffalo, or even to much greater distances as in the case of power plants on the Pacific coast where mountain streams and lakes are employed for this purpose with considerable efficiency. A high tension alternating current thus can be transmitted over considerable distances and then transformed into direct current which flows along the trolley wires and is utilized in the motors. This transformation is usually accomplished by means of a rotary converter, that is, an alternating current motor which carries with it the essential elements of a direct current dynamo and receiving the alternating current of high potential turns it out in the form of direct current at a, lower and standard potential. The alternating current at high potential can be transmitted over long distances with a minimum of loss, while the direct current at lower potential is more suitable for the motor and can be used with greater advantage, yet its potential or pressure decreases rapidly over long lengths of line, so that it is more economical to use sub-stations to convert the alternating current from the power plant. It must not be inferred, however, that all electric railways employ direct current machinery. In Europe alternating current has been used with great success and also in the United States where a number of lines have been equipped with this form of power. But the greater number of installations employ the direct current at about 500-600 volts and this is now the usual practice. Whether it will continue so in the future or not is perhaps an open question.

The electric car, as we have seen, employs a motor which is geared to the axle of the driving trucks, and the current is derived from the trolley wire by the familiar pole and wheel and after flowing through the controller to the motor returns by the rail. The speed of the car is regulated by the amount of current which the motorman allows to pass through the motor and the circuits through which it flows in order to produce different effects in the magnetic attraction of the magnet and the armature. In the ordinary electric car for urban or suburban uses there has been a constant increase in the power of the motor and size of the cars, as it has been found that even large cars can be handled with the required facility necessary in crowded streets and that they are correspondingly more economical to maintain and operate.

The success of electric traction in large cities had been demonstrated but a few years when it was appreciated that the overhead wires of the trolley were unsightly and dangerous, especially in the case of fire or the breaking of the wires or supports. Accordingly a system was developed where the current was obtained from conductors laid in a conduit on insulated supports through a slot in the centre of the track between the rails. A plow suspended from the bottom of the car was in contact with the conductors which were steel rails mounted on insulated supports, and through them the current passed by suitable conductors to the controller and motors. This system found an immediate vogue in American cities, and though more costly to install than the overhead trolley, was far more satisfactory in its results and appearance. In certain cities, Washington, D. C., for example, the conduit is used in the built-up portion of the town and when the suburbs are reached the plow is removed and the motors are connected with the trolley wire by the usual pole and wheel.

Perhaps the most important feature of the electric railway in the United States has been the development and increase of its efficiency. Wherever possible traffic conditions warranted, it was comparatively easy to secure the right of way along country highways with little, if any, expense, and the construction of track and poles for such work was not a particularly heavy outlay. It was found, as we have seen, that the current could be transmitted over considerable distances so that the opportunity was afforded to supply transportation between two towns at some small distance where the local business at the time of the construction of the road would not warrant the outlay. This led to the systems of interurban lines, small at first, but as their success was demonstrated, gradually extending and uniting so that not only two important towns were connected, but eventually a large territory was supplied with adequate transportation facilities and even mail, express, and light freight could be handled.

Again the success of such enterprises made it feasible for the electric railways to forsake the public highway and to secure a right of way of their own, and gradually to develop express and through service, often in direct competition with the local service of the steam railways in the same territory. Here larger cars were required and power stations of the most modern and efficient type in order to secure proper economy of operation. The general character of machinery, both generators and motors, was preserved even for these long distance lines, and their operation became simply an engineering problem to secure the maximum efficiency with a minimum expenditure.

With the success of electric railways in cities and for suburban and interurban service naturally arose the question, why electric power whose availability and economy had been shown in so many circumstances could not be used for the great trunk lines where steam locomotives have been developed and employed for so many years? The question is not entirely one of engineering unless as part of the engineering problem we consider the various economic elements that enter into the question, and their investigation is the important task of the twentieth century engineer. For he must answer the question not only is a method possible mechanically, but is it profitable from a practical and economic standpoint? And it is here that the question of the electrification of trunk lines now rests. The steam locomotive has been developed to a point perhaps of almost maximum efficiency where the greatest speed and power have been secured that are possible on machines limited by the standard gauge of the track, 4 feet 8 1/2 inches, and the curves which present railway lines and conditions of construction demand. Now, withal, the steam locomotive mechanically considered is inefficient, as it must take with it a large weight of fuel and water which must be transformed into steam under fixed conditions. If for example, we have one train a day working over a certain line, there would be no question of the economy of a steam locomotive, but with a number, we are simply maintaining isolated units for the production of power which could be developed to far greater advantage in a central plant. Just as the factory is more economical than a number of workers engaged at their homes, and the large establishment of the trust still more economical in production than a number of factories, so the central power station producing electricity which can be transmitted along a line and used as required is obviously more advantageous than separate units producing power on the spot with various losses inherent in small machines.

But even if the central station is theoretically superior and more economical it does not imply that it is either good policy or economy to electrify at once all the trunk lines of a country such as the United States and to send to the scrap heap thousands of good locomotives at the sacrifice of millions of dollars and the outlay of millions more for electrical equipment. In other words, unless the financial returns will warrant it, there is no good and positive reason for the electrification of our great trans- continental lines and even shorter railroads. That is the situation to-day, but to-morrow is another question, and the far- seeing railroad man must be ready with his answer and with his preparations. To-day terminal services in large cities can better be performed by electricity, and not only is there economy in their operation, but the absence of dirt, smoke and noise is in accord with public sentiment if not positively demanded by statute or ordinance. Suburban service can be worked much more economically and effectively by trains of motor cars, and time table and schedule are not limited by the number of available locomotives on a line so equipped. On mountain grades, where auxiliary power or engines of extreme capacity are required, electricity generated by water power from melting snow or mountain lakes or streams in the vicinity may be availed of. Under such conditions powerful motors can be used on mountain divisions, not only with economy, but with increased comfort to passengers, especially where there are long tunnels. All this and more the railway man of to-day realizes, and electrification to this extent has been accomplished or is in course of construction. For each one of the services mentioned typical installations can be given as examples, and to accomplish the various ends, there is not only one system but several systems of electrical working, which have been devised by electrical engineers to meet the difficulties.