. Railroad construction : theory and practice : a textbook for the use of students in colleges and technical schools . s and even tie plates. Ithas been impossible to estimate the probable life of these a reasonably close estimate of the life of steel ties canbe determined, no proper comparison can be made of theireconomy relative to that of wooden ties. A study of TableXXXIV will show that a tie which costs, say three times asmuch as a cheap tie, must last more than three times as longin order that the annual charge against the tie shall be as lowas that of the cheaper tie. For exa
. Railroad construction : theory and practice : a textbook for the use of students in colleges and technical schools . s and even tie plates. Ithas been impossible to estimate the probable life of these a reasonably close estimate of the life of steel ties canbe determined, no proper comparison can be made of theireconomy relative to that of wooden ties. A study of TableXXXIV will show that a tie which costs, say three times asmuch as a cheap tie, must last more than three times as longin order that the annual charge against the tie shall be as lowas that of the cheaper tie. For example, let us assume thatthe cost of a metal tie, laid in the track, is and that itwill last 20 years. From Table XXXIV we may find that theannual charge against at 5% for 20 years = ()+ = c. Compared with a tie costing 65 c, plus 20 track laying, we find that the cheaper tie will only c. per year even if it only lasts 5 years. Of course theclaimed advantage of better track and less cost for track main-tenance, using steel ties, will tend to offset, so far as it is true,. CARNEGIE STEEL TIE (1905) Plate VI.—Some forms of Metal Ties.{Between pp. 251 and 252.) i^. § 223. TIES. 253 the disadvantage of the extra cost of the metal tie. Evenif the extra work per tie amounts to only one-half hour forone man in a year, the cost of it, say 6 c., will utterly changethe relative economics of the two ties. 221. Fastenings. The devices for fastening the rails to theties should be such that the gauge may be widened if desired oncurves, also that the gauge can be made true regardless of slightinaccuracies in the manufacture of the ties, and also that shimsmay be placed under the rail if necessary during cold weatherwhen the tie is frozen into the ballast and cannot be easilydisturbed. Some methods of fastening require that the base ofthe rail be placed against a lug which is riveted to the tie orwhich forms a part of it. This has the advantage of
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