It is very difficult to obtain reliable figures regarding rail wear and especially of the rail wear on curves. Such figures as are obtainable are almost hopelessly contradictory. The author has corresponded with the Chief Engineers or Engineers of Maintenance of Way of several prominent railroads in the hope of collecting such data. Very few satisfactory answers were obtainable. Usually the answers gave merely the average total life of rails on tangents and on various curves. It should not be forgotten that almost the only value of the figures quoted below lies in the statement of the relative life on the various curves of any one division of a road where the rails are of the same kind and are subject to exactly the same train-loads. One such statement is given by Mr. W. B. Storey, Jr., Chief Engr. of the A. T. & S. F. Rwy. The statement gives the approximate times of rail removal of 75-lb. A. S. C. E. rails on mountain curves of that road, on which the freight-trains are hauled by "Santa F‚" engines, which are decapods with trailing wheels, and have a very long wheel-base.
6 to 8 yrs
The relative life of these rails is better appreciated by a consideration of the curves of Fig. 17.
Fig. 17. Total rail life in months.
A similar statement was furnished by Mr. A. C. Shand, Chief Engr. of the P. R.R. This statement" does not differentiate between the wear on the outer and inner rails. It gives the average life of 100 rails which are subject to the very heavy traffic of their main line.
The curve indicating these values has also been shown in Fig. 17.
A comparison of these rates of wear apparently indicates that, although the rate of rail wear is less (under the given conditions) on the A. T. & S. F. than on the P. R.R., the reduction in rail life, by increasing the curvature from 4° to 9°, is far greater on the A. T. & S. F. than on the P. R.R. More important, however, is the agreement of both curves that they are concave upward. A considerable part of rail wear is independent of whether the track is curved or straight. The rails on a curved track are subject to all forms of wear which reduce the life of rails on a straight track and much other wear in addition. If we draw a straight horizontal line through the "120," the vertical distance down to the P. R.R. curve at any point indicates the reduction in the life of the rail on account of curvature. This reduction is less per degree of curve as the curvature is sharper. Although we do not know where the "tangent" ordinate belongs for the A. T. & S. F. curves, it is evident that the same principle holds good. This only verifies the theoretical deduction previously made that the longitudinal slipping (and the amount of rail wear it causes) is independent of the radius.