. Elements of railroad track and construction . ch and B 6 is 6J inches, B 6 is 6 inches, and the angleh AiB =Uk B =s; and in the triangle &A B. sm s AB = ^ = 2S («1> from which Table XV may be computed. TABLE and Angles. Length of Switch-rail, S. Frog. No. Actual Theoretical Switch Angle, s. Feet. Feet. 4 2° 36 19 5 2 36 19 6 2 36 19 7 1 44 11 8 1 44 11 9 1 44 11 10 1 44 11 12 1 18 08 16 0 52 05 18 0 52 05 20 0 52 05 24 0 52 05 129. The Practic
. Elements of railroad track and construction . ch and B 6 is 6J inches, B 6 is 6 inches, and the angleh AiB =Uk B =s; and in the triangle &A B. sm s AB = ^ = 2S («1> from which Table XV may be computed. TABLE and Angles. Length of Switch-rail, S. Frog. No. Actual Theoretical Switch Angle, s. Feet. Feet. 4 2° 36 19 5 2 36 19 6 2 36 19 7 1 44 11 8 1 44 11 9 1 44 11 10 1 44 11 12 1 18 08 16 0 52 05 18 0 52 05 20 0 52 05 24 0 52 05 129. The Practical Turnout.—^The practical turn-out from a straight track is shown in Fig. 78, the fourprincipal lines representing the gauge-lines of the PRACTICAL TURNOUTS. 133 rails. The longer turnout rail consists of the circularlead-curve, B C, the straight switch-point rail, A B,and the straight frog-wing, C P, both being tangentto the lead-curve. In addition to the definitions in 1fl08, Fig. 66, letthe following symbols be assumed: AiA c H N M. rl^i / ^^^^^-^-_—-—. yj 1, // / C^^M 11* / ^~^-^^^^^s^:5r:rr =^ w Fig. 78a. ^ i Fig. 78. S =the theoretical length of switch-rail;S =the actual length of switch-rail;s = switch-rail angle =c 0 B =H Ai B, Fig. 78, or deB, Fig. 78a. k =length of toe wing-rail of frog =P C =P C, Fig. 78. In Fig. 78, Ai is the theoretical point of switch-rail, B is the heel of switch-rail, C is the toe of frog, and P is the theoretical point of frog. In the triangle HAiB. smHAiB = -r—f,, orAlt) sm s = S (62)^ 134 RAILROAD TRACK AND CONSTRUCTION. Since the A. R. E. A. recommends that the thick-ness of the point be ^ inch, then taking h and S infeet, we have h - ,„_,-sm s = g (620 130. To Find the Long Chord B C—In Fig. 78,continue the tangents Ai B and C P until they meetat I, draw the hne 0 I, and P M normal to the maintrack, and project B to K and C to L, then the angleKBC=IBC + KBI=i(F-s) + s=i(F + s), and theangle E I C =B 0 C =F -s. Then in t
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