International Correspondence Schools · Scranton, Pa. : The Colliery engineer co. · leaf 267
cial estimate is made for each bridge. The cost ofbridges increases rapidly as the span increases. In metalbridges the cost will increase about as the square of the 856 RAILROAD LOCATION. span, i. e., if one bridge has twice as great a span as another,the first will cost tlie square of 2 or 4 times… … i 4.4ft. level, and the areas are calculated from the center cuts andfills. Let Fig. 377 represent the actual cross-section at agiven station, and Fig. 378 the cross-section based upon thecenter cut. The area of the section A B C D in Fig. 377,calculated from the actual cross-sections, is 160.78…
Railroad engineering
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