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

Not one half of railroads are built for the original estimate. In few cases has sufficient allowance been made for the sacrifice undergone in negotiating the companies’ securities. All general instructions that can be given relating to the determination of prospective profits, are, to keep the estimate of constructing and working expenses high, and that of the assumed traffic low; not so low, however, as to require a too lightly built road.

MECHANICAL PRINCIPLES OF LOCOMOTION.

12. The superiority which the modern railroad possesses over the common, McAdam, plank, or turnpike-road, consists, first, in the reduction of the resistance to motion, and second, in the application of the locomotive steam-engine.

13. The effect of grades of a given incline upon a railroad is relatively more than upon common roads; for as the absolute resistance on a level decreases, the relative resistance of grades augments: whence to obtain the full benefit of the system, we must reduce much more the grades and curvature upon a railroad, than on a common road. For example, if the resistance to moving one ton upon a level upon a railroad was ten pounds, and upon a common road forty pounds, where a twenty-three feet grade would be admissible upon the former, we might use an incline of ninety-three feet per mile upon the latter.

14. The resistance to the motion of railroad trains increases rapidly with the speed;[^[1]] whence the grades of a passenger road where a high average speed is used, may be steeper than those of a road doing a freight business chiefly.

[1]. See chapter XIV.

DETERMINATION OF CHARACTER OF ROAD.

15. Upon a correct idea of what the road ought to be, depends in a great degree its success. The amount of capital expended upon the reduction of the natural surface, depends upon the expected amount of traffic. The traffic remaining the same, the greater the capital expended in reducing grades and curvature, the less will be the working expense; and the less the construction capital, the greater that for maintenance. The limit of expenditure must be such as to render the sum of construction and maintaining capital a minimum.

The bad effect of grades upon the cost of maintaining and of working railroads, is not so great as many suppose. Of the whole cost of working, only about forty per cent. can be charged to locomotive power; and of this, not more than sixty-two per cent. is effected by grades.[^[2]]

[2]. See appendix F.