. The elements of railroad engineering . ertical. If rockis encountered before the rock excavation is commenced,the slope is contracted to \ horizontal to 1 vertical. It has been customary to plat irregular sections on crosssection paper. The original or surface cross-sections arefirst platted, and when the top material (usually earth) hasbeen removed, a cross-section of the remaining material istaken and platted on the original sheet, the lines being 10-22 RAILROAD CONSTRUCTION. drawn in colored ink. If there is still another classificationof material, as shown in Fig. 4K7, a final cross-sect
. The elements of railroad engineering . ertical. If rockis encountered before the rock excavation is commenced,the slope is contracted to \ horizontal to 1 vertical. It has been customary to plat irregular sections on crosssection paper. The original or surface cross-sections arefirst platted, and when the top material (usually earth) hasbeen removed, a cross-section of the remaining material istaken and platted on the original sheet, the lines being 10-22 RAILROAD CONSTRUCTION. drawn in colored ink. If there is still another classificationof material, as shown in Fig. 4K7, a final cross-section istaken and platted in lines of a separate color. The different colored lines at once indicate the outlines ofthe various materials and assist in checking the calculationsof the partial areas. The original cross-sections and the fin-ished section should be in black, the others in distinct, sep-arate colors. The partial areas are easiest calculated by dividing theminto triangles and carefully scaling all dimensions noteiven. hyCut 13. Fig. 487. In Fig. 487 Ave have, remembering that the slopes of f gand c h are 1 to 1: of triangle a ^ c of solid rock = 9x2 = of triangle (5 ^/of loose rock = 9x1 — of triangle ^ <Zof loose rock = =~ of triangle c b k of loose rock = = sq. of triangles ^//& of loose rock = sq. ft. of triangle c/<? _^ of earth = sq. of triangle rt^/; of earth =34. = sq. ft. area of section ft. 159(). (Quantity Books.—Quantity books spoken ofin Art. 1588 are of various forms. The following is rec-ommended. It contains station and cross-section notes ofFig. 487, together with the end areas: RAILROAD CONSTRUCTION. 1023 -: 1 1 ^ &- <u (U X3 ^ fe o o _o if) e< ,S 3 t/i ^4^ 6 o o 3 a tlH o rt CTj +J (U o +-> O V- o H i ^ a t3 ^ o o o ^ rn Pi 1-H t« +j 03 3 <U u &l
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectrailroadengineering
