. Railroad construction, theory and practice; a text-book for the use of students in colleges and technical schools . Fig. 42. and fill are required, and the points c and d are determined asbefore. Note that /? and /? are not necessarily equal. Theirproper values will be discussed later. 89. Terminal pyramids and wedges. Fig. 43 illustrates thegeneral form of cross-sections when there is a transition fromcut to fill. ,g represents the grade line of the road which. Fig. 43. passes from cut to fill at d. sdt represents the surface cross-section taken at the point where either side o
. Railroad construction, theory and practice; a text-book for the use of students in colleges and technical schools . Fig. 42. and fill are required, and the points c and d are determined asbefore. Note that /? and /? are not necessarily equal. Theirproper values will be discussed later. 89. Terminal pyramids and wedges. Fig. 43 illustrates thegeneral form of cross-sections when there is a transition fromcut to fill. ,g represents the grade line of the road which. Fig. 43. passes from cut to fill at d. sdt represents the surface cross-section taken at the point where either side of the road-bed first cuts the surface (the point m in this case) will usuallybe triangular if the groimd is regular. A similar cross-sectionshould be taken at o, where the other side of the roadbed cutsthe surface. In general the earthwork of cut and fill terminates 106 RAILROAD CONSTRUCTION. § 90. in two pyramids. In Fig. 43 the pyramid vertices are at nand k, and the bases are Ihm and opq. The roadbed is generallywider in cut than in fill, and therefore the section Ihm and thealtitude In are generally greater than the section opq and thealtitude ph. When the line of intersection of the roadbed andnatural surface (nodkm) becomes perpendicular to the axis ofthe roadbed (ag) the pyramids become wedges whose bases arethe nearest convenient cross-sections. 90. Slopes, a. Cuttings. The required slopes for cuttingsvary from perpendicular cuts, which may be used i
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