Page images
PDF
EPUB

APPLIED SCIENCE.

DURING the last few months two subjects have received serious discussion, both by professional engineers and by an interested public. Both of these relate to problems in railway operation, the one being the application of electric traction to main-line railway service, and the other the question of minimizing railroad accidents. These have already received attention in THE FORUM, but, like other important problems, they will continue to excite discussion until they are so far settled as to fall back into the great mass of events which flow along in the current of life and work without disproportionately obtruding themselves.

Like many other important developments, main-line electric railway traction is not being pushed forward by railroad men themselves. Indeed, there is little doubt that if the question were submitted to a body consisting of railway engineers and superintendents alone, the opinion would be an adverse one, or at least one of indifference. This is the usual course in the case of radical changes, and such wholesale modifications are nearly always brought about by the efforts and influence of those who may be described by the current phrase as "rank outsiders." Nevertheless, the railroad managers have been compelled to adopt electric traction for such purposes as they find cannot be accomplished by steam locomotives; and thus the thin end of the wedge is being introduced, and the pressure to drive it further in will doubtless continue to be applied. I have already referred to the successful trials of the electric locomotive for use in connection with the hauling of trains in the Park Avenue tunnel of the New York Central terminal in New York City. Similar machines will undoubtedly be employed to haul the trains through the Pennsylvania tunnel under the Hudson to the new station in New York; and, with the experience thus gained, the extension of the service may well be expected.

One of the standard arguments against the application of electric traction has been the large amount of capital at present invested in steam locomotives, and the impossibility of sinking such a sum by scrapping these valuable machines. As a matter of fact, the effective

life of a steam locomotive is hardly more than ten or twelve years, and but a small proportion of the engines now in active service are of the latest and most efficient models. As soon as the lines are equipped to use electric traction at all, the replacement of the antiquated steam locomotives by electric machinery may begin as a continuous operation.

A common fallacy, in connection with discussions of the subject, is that of considering electric traction merely as a substitute for steam locomotives in connection with a service which shall be the equivalent of that now given. When it is remembered how far steam railways have surpassed horse-haulage systems for merchandise and passengers, or to what extent steamships have excelled sailing-vessels, or trolley systems outgrown horse-car lines, it will be realized how futile it is to estimate the scope of a new system by the limitations of an old one. Electric traction must give the passenger swifter, more frequent, and more complete service than is now possible with steam. It must carry the trainmile capacity of the railways far beyond the present limits, while lowering the ton-mile rate to the shipper. If it can do these things it is bound to come, while, if it can only equal the present requirements, it must be laid aside and the effort must be continued to devise something that can accomplish more than is now practicable.

The second question which has attracted so much attention among engineers and practical menthe subject of railway accidents must be considered wholly as a matter to be dealt with by the applied science of engineering. The railroad is itself an engineering proposition, and every collision or other disaster is an emphatic repetition of a fundamental law of science: two bodies cannot occupy the same space at the same time. The prevention of accidents, then, has become a problem for the engineer to solve, and he must solve it by engineering methods. In so doing, the condition must also be observed that traffic must not be impeded. Indeed, it is maintained that methods which produce absolute safety should also remove all impediments to traffic. The nearest approach to absolute freedom from danger by collision is that given by the travelling platform, and this because the entire length of the track is covered at all times. Undoubtedly the next thing to this is found in the division of the line into block sections, each block containing but one train at any one time. To permit a train to enter a block before its predecessor has left it would be equivalent to allowing the continuous platform to double up upon itself at some point a physical impossibility for the platform, and a matter which is made an impossibility for

[ocr errors]

the block system by the use of mechanical trip devices, beyond the control of the engineer on the train. Some such methods are in use already; and, while improvements in them are undoubtedly to be desired, the principle is unassailable. When fully perfected, such an automatic block method should improve rather than impede traffic, and, by removing any possibility for the exercise of discretion, either by dispatcher or engineer, convert the movement of detached trains into a continuous flow identical in action and safety with that of the travelling platform.

The advantages of the utilization of hydraulic power in connection with the generation and distribution of electric energy have been frequently discussed, and in the last issue of this review I noticed the extent to which long-distance, high-tension electric transmission had been developed in California. The success which has been attained in practice with pressures of 50,000 to 60,000 volts and distances of 150 to 200 miles has led to discussions as to the possible extension of these voltages and distances. In a paper recently presented before the American Institute of Electrical Engineers, Mr. Ralph D. Mershon examined the conditions limiting the distance to which electrical energy can be economically transmitted. Since the extent to which the voltage or electrical pressure can be increased is limited, it follows that the limiting distance to which power can be advantageously transmitted by electricity depends entirely upon the cost of the line conductor. Taking into account the commercial questions of the cost and the selling price of power, it is computed that the maximum commercial distance to which electrical energy can be transmitted is about 550 miles. This means that power can be transmitted from Niagara Falls to New York City, or from the Victoria Falls of the Zambesi to points more than twice as far away as Buluwayo-facts which may lead to transformations as yet but little considered.

On

In spite of all the difficulties which have been encountered, and chronicled from time to time in these pages, a junction has finally been effected between the two main headings of the Simplon tunnel. February 24 last, the workers on the Italian side pierced through to the Swiss heading, where work had been suspended for several months; and so, although much yet remains to be done, the perforation of the mountain is an accomplished fact. It has taken nearly a year longer than was anticipated to complete the tunnel; the delays being due to the great influx of water, both hot and cold, and to the treacherous nature.

of the rock in certain portions. With the union of the two headings, the flow of water can be controlled and the temperature reduced; and it is hoped that in a few months construction trains will be running, and that the road will be opened to the public in the late summer or early

autumn.

Apart from its length, twelve miles from Brieg to Iselle, as against nine and three-quarters for the St. Gothard tunnel, and the fact that it gives the Jura-Simplon railway a direct connection, by way of the Rhone valley, with Italy, the Simplon tunnel has especial interest for the engineer. It is the first great tunnel in which the double-bore system has been employed. The success of the method renders it probable that it will be used again. When a tunnel is bored of sufficient size to permit two trains to pass each other, there is a large amount of unnecessary removal of material in the upper portion, as will be readily seen if two circles are drawn, one about each train. For this reason the Simplon tunnel has been designed as a pair of independent bores, each one large enough for a single train. At the present time but one of these tunnels has been excavated to the full diameter, the second tunnel being made large enough to pass only a small mining car on a narrow-gauge track. The two tunnels have been run parallel to each other about fifty feet apart, with cross connections every few hundred feet, and the auxiliary tunnel has been used as a passage to carry away the material from the main bore, and also to aid in ventilation. The larger tunnel alone will be used for traffic until the demand for trains becomes sufficient to require a double track, when the auxiliary tunnel will be enlarged to the full size — a comparatively simple matter. It is planned to hold an exposition of transport appliances in Milan next year as a commemoration of the completion of the tunnel, this having been postponed for a year because of the delays in the work.

Matters are assuming more definite shape with respect to the conduct of the work on the Panama Canal. On certain portions of the line, notably in the great cut at Culebra, the excavation has never been interrupted; and the installation of several powerful steam shovels of modern design has enabled this portion of the work to be pushed, and also permitted valuable data to be gathered as to the cost of doing this excavating by improved machinery. It is not yet decided whether the sea-level or the summit-level plan will be adopted. Each has its advocates. The engineering committee of the commission has recommended the sea-level plan, with a bottom width of 150 feet, a minimum depth of

water of 35 feet, with twin tidal locks at Miraflores, of 1,000 feet length and 100 feet width. This plan will involve an expenditure of about eighty million dollars more than a lock canal of 85 feet summit level; but it has some things to recommend it. One of the important features of modern ocean transport is the continual increase in the dimensions of great steamships, and the superior commercial advantages of these large vessels are certain to bring them into general use for all purposes of economical transport. Any lock canal has a definite limit placed upon the dimensions of the vessels by which it can be traversed; and had the Panama Canal been built with the dimensions chosen by the French engineers for the canal prism and locks, it would already have become too contracted for the most efficient cargo carriers afloat.

At the same time, there are objections of definite weight against the sea-level plan. There are two bodies of water to be considered, one being the canal itself and the other the Chagres River.

If the canal is

not to be held above the level of the sea, then the Chagres River must be held up and controlled above the canal. It has been suggested that the excess flow of the Chagres can be carried through tunnels both into the Pacific and into the Caribbean; and one or both of these tunnels, as well as a great dam at Gamboa, will be required to control the Chagres River. That the sea-level plan can be carried out is not denied; but it is a question whether it is the best, in view of all the conditions. In any case the canal must be proportioned upon dimensions which will admit the great cargo-carriers which have been found so economical in transatlantic service, and this can be done by either plan if sufficient effort is made at the start.

In connection with the subject of canal locks, the question of mechanical lifts on inland waterways continues to receive attention. I have recently spoken of the new hydraulic canal lift on the Trent Canal, at Peterborough, Ontario, and now a new project has been brought forward to accomplish a similar result in a different manner. In order to obtain the most satisfactory results on the proposed Danube-Oder Canal, in Austria, a prize competition has been held, and the highest awards have been given to two entirely different designs. One of these is not new, consisting of a modification of the well-known inclined-plane system, the boats being drawn up in tank-cars carried on trucks. The other prize design is an altogether different system. It includes the use of a great revolving drum, made of a steel framework, and greater in diameter than the total height of the lift. This drum, which is some

« PreviousContinue »