International Correspondence Schools · Scranton, Pa. : The Colliery engineer co. · leaf 353
942 RAILROAD CONSTRUCTION. transit. The tangent distances are calculated and the P. C.and P. T. located by direct measurement. The work andcalculations are repeated many times, and every possibleprecaution taken to secure perfect accuracy of results. … Grade-hO. 75 FIG. 430. The sketch given in Fig. 429 shows the difficulties attendingthe laying out of the Rockport tunnel on the Lehigh ValleyRailroad. The original line A B C D followed the course of theLehigh river, which hugs the bluflf E. The tunnel lineA F G H would have been adopted and the…
Railroad engineering
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