. Building and repairing railways ... : Forming one of the series of the volumes comprised in the Revised and enlarged edition of The science of railways, . construction is lessthan masonry. In some cases as much as 30/S incost is claimed to be saved but this will of neces-sity depend on local conditions. At one localitythe cost of a stone which will stand the weathermay be expensive and at another it could besecured at a moderate figure—again the differ-ence in the cost of cutting and dressing stonesecured from different quarries must be consid-ered. For these reasons the percentage of saving
. Building and repairing railways ... : Forming one of the series of the volumes comprised in the Revised and enlarged edition of The science of railways, . construction is lessthan masonry. In some cases as much as 30/S incost is claimed to be saved but this will of neces-sity depend on local conditions. At one localitythe cost of a stone which will stand the weathermay be expensive and at another it could besecured at a moderate figure—again the differ-ence in the cost of cutting and dressing stonesecured from different quarries must be consid-ered. For these reasons the percentage of savingin any contemplated work will differ accordingto local conditions. There are several methods of using metal andconcrete, which are protected by patents, themethods can be divided into two general using the merchant sizes as found in themetal trade. Second specially designed forms tocarry out the ideas of inventors. The **Melan system, where beams and othermerchant forms are imbedded in the concretebelongs to the first class, this style is shown inFig. 215p. The Thacher^ system uses merchant steel or 352 BUILDING AND REPAIRING Fig. 215p. MELAN ARCH BRIDGE, OVER FALLS CREEK, INDIANAPOLIS, IND. iron bars and to increase the adbesion of theconcrete, steel rivets are placed in the two systems are types of the first forms,the following systems are types of the secondforms. Corrugated bars, specially rolled with enlargedribs on the rods to increase the adhesion of theconcrete and make the concrete and steel a moreuniform mass. This is illustrated in Fig. 215qand the method of incorporating it in the con-crete is shown in Figs. 215t and 215u. Twistedbars are another method adopted to increase the STANDARDS OF CONSTRUCTION. 353
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectrailroa, bookyear1906
