. The elements of railroad engineering . 942 RAILROAD CONSTRUCTION. transit. The tangent distances are calculated and the P. P. T. located by direct measurement. The work andcalculations are repeated many times, and every possibleprecaution taken to secure perfect accuracy of 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 tunnel dr
. The elements of railroad engineering . 942 RAILROAD CONSTRUCTION. transit. The tangent distances are calculated and the P. P. T. located by direct measurement. The work andcalculations are repeated many times, and every possibleprecaution taken to secure perfect accuracy of 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 tunnel drivenwhen the road was first constructed, but a rival line wasbuilding on the opposite side of the river, and there was a RAILROAD CONSTRUCTION. 943 race to reach the Wyoming Valley coal fields and commandthe coal traffic. The tunnel line was accordingly postponedand the river line adopted. After a lapse of twenty yearsthe tunnel was driven in 1882-3. The neck F G throughwhich the tunnel passes (a profile of which is shown in ) reached a height of more than 300 feet. The hillsideswere so steep that in places a man could hardly stand. Thetangent K F is the prolongation of the original tangent A grade of the original line was about 20 feet per mile,and as there was a gain i
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectrailroadengineering
