term it the cost of one Train-mile. The items which go to make up the expense of the train-mile are as follow: Taking, then, $1.00 as the cost per train-mile, and assuming the interest on the amount capitalized at 6 p. c., we obtain the following table: This assumes that each "daily" train only runs 350 days in the year, which makes a sort of allowance for Sundays, "specials," etc. 37. From the above we see that if we have ten trains making the round-trip every day, we are entitled to spend $58,333 extra on the construction of a certain route, if by so doing we can save a mile of level track; so also we should be entitled to spend $388 in the reduction of a foot of rise and fall. Thus with 10 daily trains we might safely expend 2 × $388 $776 in lowering (only one foot) such a summit as C in Fig. 3; but if Chad been the terminus of the line AC we ought only to spend $388 in lowering it one foot. = Suppose again we have two routes to select from, one of which would probably cost $40,000 more than the other, but would shorten the distance by one mile and would save a rise and fall of 100 feet. Then if there are only likely to be three trains running—including returning each day, we are not entitled to spend more than ($5833+ $3888) × 3 = $29,163 to save the above distance and rise and fall; therefore it would probably be injudicious to adopt the more expensive route. 38. As regards the cost of operating Pusher-grades, we find that a Pusher kept pretty busy costs on an average about $280 per mile of incline per annum-i.e., $140 per mile run-" all that the engine fails to do below 100 miles per day may be assumed to cost from to as much as if it had been run, and is so much added to the cost of what is run. Thus on a 5-mile incline, with only 4 trains to be taken up it each day, the probable annual expense of the Pusher will be found thus: Work done, 4 × 5 × $280 = $5,600 Had we been able to reach the summit without adopting a Pusher-grade-supposing the total rise and fall to be 1000 feet -the cost of "Rise and Fall" would have been for the 4 daily trains 4 × 1000 × $2.33 = $9320, representing a difference in the operating-expenses of $1620 per annum, which at 6 p. c. would have warranted our expending $27,000 more on the route which involved the Pusher-grade, assuming curvature and distance to be the same in both cases. 39. To test the merits of different routes as regards operating-expenses, we may express them in terms of their Equivalent Lengths (L) in miles thus: where H C L=1+ + = actual length in miles, C= total curvature in degrees. 40. As regards the increase in operating-expenses caused by any slight increase in distance, such as is the result of changes in the alignment, it is not usually the case that the cost per train-mile for any small additional distance is as high as the rate already given; for many of the items, such as station and terminal expenses, which go to make up the average cost per train-mile, are not affected by an addition in distance which does not exceed 2 or 3 p. c. of the total length of the road. Thus, in selecting the choice of two routes, the engineer should not necessarily take the average cost per train-mile as his standard by which to find the probable difference in the operating-expenses, but in most cases may consider about 50 cents per train-mile an amply sufficient allowance for that portion of the longer route which is in excess of the other, when that excess does not exceed the above amount. 41. In order to approximate as closely as possible to the probable cost per train-mile on any projected road, the engineer must judge by the results on other roads where the conditions are more or less similar. Where changes are to be made in the alignment of a road already in operation, the value of the proposed improvements can then be found with considerable accuracy, since the cost per train-mile is then known. RECEIPTS. 42. The Receipts usually vary from about 1.5 to 2.0 the cost of operating; and it is not often that the locating-engineer has it in his power to affect them in any way. He may, however, by carrying the location by a slightly more circuitous route than he would otherwise have adopted, catch the traffic of some outlying village. Mr. Wellington on this subject says: "When the question comes up of lengthening the line to secure way-business, we may almost say that where there seems any room for doubt, it will almost always be policy to do so. Extra business to a railroad—the engineer will rarely err in thinking—is almost always clear profit. Of Passenger business this is literally true until the increase becomes considerable; of Freight business it is so nearly true that 80 or 90 per cent at least of the way-rate is clear profit over the usual cost of any particular shipment." Thus, suppose we are projecting a line between two points 100 miles apart, and that half-way between them lies a small town 10 miles off the direct route. The additional distance involved in running through it is about 2 miles. Suppose, as is a reasonable estimate, the average payment per head of population is $13 per annum. Then, if there are likely to be 5 daily trains, we may put the extra cost of the two miles, including the interest on the capital spent on their construction, at about $2000 per annum. Therefore, looking at the matter only from this point of view, if the place contains, or is likely to contain before long, only about 150 people, it would probably be wise to locate the road through it. COST OF CONSTRUCTION. 43. This is a subject which had almost better be omitted, for the range of prices is so great in different parts of the country, that values given to suit one place may be entirely misleading when applied to another place a few hundred miles off. I have, however, endeavored to strike the average prices as nearly as possible, and with these remarks they must be taken for what they are worth. They show more or less the relative cost of various works, and in this way may sometimes be of service. First we have the following lot common to all track: Then we have the following, according to circumstances: By taking the mean prices of the first set, we obtain for an average mile of standard-gauge track (10 p. c. short rails) the following cost: Besides these we have, of course, Right of Way, Engineering, Law, and a variety of Incidental expenses. As regards the cOST OF TRESTLEWORK, we find that for Low Pile Trestles-say 20 ft. high-assuming piling to cost 50 cents per lin. ft. driven, and the superstructure $20 per M., the cost will usually be about $6 per foot run. For a Wooden Trestle 50 feet high at $25 per M., the cost, if resting on piles or sills, will usually be about $10 per foot run; but if 100 feet high, $20 to $25 per foot run. The cost of Iron Trestlework varies so enormously according to the design, that it is impossible to lay down any figures which might be generally applicable. Assuming, however, that the total weight of iron in the trestle equals the total weight of wood in an equally strong wooden trestle, the cost, at 5 cents per lb., would be about double that of a wooden one. These figures are of course exclusive of Masonry foundations, and are for single-track. As regards the COST OF TRUSSES, a Wooden Howe Truss-single-track, of 100 ft. span, Lumber at $15 per M.-costs, framed, somewhere about $2000; and an Iron Truss of the same span, at 5 cents per lb., costs about $5000. The cost in both cases varies pretty much as the square of the span. Erecting usually costs from $5 to $10 per lin. foot. As regards the COST OF TUNNELLING, we may say it varies from $2.50 to $7.50 per cu. yd.; so that for a single-track tunnel we may consider the price per foot run to vary from about $30 to $80, including masonry. The cost of sinking a shaft or driving a heading is considerably higher in proportion than this. For more on the subject of the Cost of Grading, see Sec. 124, Part II. |
