Handbook of Railroad Construction; For the use of American engineers. / Containing the necessary rules, tables, and formulæ for the location, construction, equipment, and management of railroads, as built in the United States.

by George L. Vose

16. The degree of curvature to be admitted upon any road depends somewhat upon the speeds at which trains are to be run. The larger the radius of curvature, the greater may be the speed; at the same time the elevation of the exterior rail upon curves may be less, and therefore more adapted to freight trains. High rates of speed are considered upon some competing roads necessary; but are, even in such cases, necessary evils. The wear of cars and of engines, of permanent way and of bridges, increase in a rapid ratio with the velocity. The maximum speed for freight trains should never exceed fifteen miles per hour, or for passenger trains from twenty to twenty-five miles per hour.[^[3]]

[3]. See chapter XVI.

17. The agricultural nature of the country and its commercial position, will determine the nature of the traffic, whether passenger or freight, and also the amount. The amount and nature of the traffic will limit the curvature, and will partially determine the arrangement of grades.

GAUGE.

18. The question of broad and narrow gauge has led to much discussion, and both plans claim among their advocates some of the best engineers. The narrow gauge (American and English,) is four feet eight and one half inches (from inside to inside of rail). The maximum adopted, is (the Great Western of England) seven feet. The American maximum (New York and Erie, and Ohio and Mississippi) is six feet. There is also in America four feet ten inches, five feet, and five feet six inches. The advantage of the broad gauge for a road doing an extensive business, is the increased stowage room in freight cars, thus rendering admissible shorter trains; by which the locomotive power is more directly applied on curves. More comfortable passenger cars, (the same length of car of course accommodates the same number of passengers). The disadvantages of a wide gauge are, increased expense of cutting, embanking, bridging, and masonry; increased expense of engines, cars, rails, sleepers, and all machinery; more wear and tear upon curves, by reason of greater difference between the lengths of inner and outer rails, and increased atmospheric resistance to fast trains, from increased bulk.

19. The general conclusion arrived at by a commission appointed by the Great Western Railway Company, (England,) consisting of Messrs. Nicholas Wood, J. K. Brunel, and John Hawkshaw, was, that four feet, eight and one half inches was rather narrow, but still enough for a certain class of roads; that two or three inches made no material difference; that seven feet was too wide for any road; that the weight of the broad gauge engine, compared with the small increase of power, was a serious evil; that engines could be run with perfect safety upon the narrow gauge at any speed from thirty to sixty miles per hour, and that no more had been attained upon the broad; that rolling friction was less upon the broad, owing to the increased diameter of wheels, but that friction from curves and atmospheric resistance was greater.

20. D. K. Clark, in “Railway Machinery,” p. 300, 301, makes the resistance as deduced from experiments made upon both the four feet, eight and one half inches, and the seven feet gauge, considerably greater upon the former than on the latter; but as the narrow gauge trials were made upon a curved road, with rails in a bad state, in average weather, while those upon the broad were made in good weather, upon a good and straight line, he leaves the gauge question open, and uses the same formula for all widths.

21. Want of increased power, can be an apology for increased gauge, until the capacity of the narrow gauge has been filled. The strongest engines in the world are upon the four feet, eight and one half inch gauge. No engines in America surpass or compare for absolute strength, with those upon the Baltimore and Ohio Railroad. The most powerful passenger engine ever built for high speeds, is Crampton’s engine “Liverpool,” (London and North-western Railroad, England,) gauge four feet, eight and one half inches.

GENERAL ESTABLISHMENT OF ROUTE.

22. The straight and level line connecting any two points, is of course the best for the completed road; but this is seldom practicable. Way towns must be accommodated to a certain extent; but the main line should not be lengthened on that account, unless the traffic and capital furnished by such town is not only sufficient to pay for the construction and maintenance of the extra length, but also to carry the entire through traffic over such increased distance. If the town is unable to support such a burden, it may be able to build and maintain a branch.