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l ' <br /> A <br /> - <br /> REDUCTION TABS. <br /> QWrlsht,1914,by Euot»Die6asen Go4,NRw 1P.6rk P► <br /> Ll <br /> 7° <br /> A <br /> C <br /> f /f 0 <br /> CURVE FORMULAS <br /> 1 Radius=R= <br /> nsT�Si3(1)Degree of Curve-D and sin.a—a(2) <br /> o -- Tangent=T=Rtan� (3)Length of Curve=L=100$(4) <br /> ?8> ° _ Middle ordinate=M=R(1—cos. (5) =Rvere (6) <br /> - _ External=E=Ttan`-(7)=R=coo4—R(8)=Ressec4(9) <br /> Long Chord..=C=2 R sin.z(10)G=Central Angle <br /> EXPLANATION AND USE OF TABLES <br /> Stations.--Given P. I.=Sta. 161+60.35 to find %L of f C <br /> -" and P. T. A-620 10' D=8° 20'. From Table.IV for 1 curve'Il— <br /> $454.1 <br /> and.++ —414.49 ft. From Table V oorrection=.36 o <br /> 414.85 ft. P. C.—Sta. P.I.—T-157+45.50. Also from (4) 1,-- <br /> 746.00 and P.'T.=s8ta.P.C.+L=164+91,50. <br /> p11+eele.Tangent offsets vary (approximately) dlreotl nth <br /> D and with=of t11��e distance. Thus tangent offset for 5(a. <br /> -- 158 on ebdVre curve is 2.16 ft.found as follows. From Table III tangent' <br /> offset for.106 ft.-7.27 ft. Distance-15$--8ta.P. C.--54.50t Dense <br /> *ffeet�7.27 (54.50-x•100)2-2.16 ft. Also square of any distaw <br /> --- divided by twig the radius equals(approximately)the distance from <br /> tangent to curve. Thus (54.50)t+(2x688.26)=;;2.I6-ft. <br /> - Peffectlons.—DefleWon an5le=1 D for 100 ft., Y D for 50 ft., <br /> etc. For c ft.=(im.minutes).3 x C x °or—defl.for 1 tt.from Table <br /> — <br /> 2 I x(n. For S, 158 of above =re=.3 x 54.5 xSH—j36.2' .pr <br /> ,16,2',or�++8. UAP-136.2'from.Table III For Eta. 159 deflec- <br /> --- tion p 4e=2°16. +80 20'3-2=$°98:21,etc. <br /> Rxternah- -May be found is almi*manner to.tanputI !Thus, <br /> = E fog'curve above is 91.37, For from Table IV for P curve. 6 <br /> fpr 8°,20'=980.6+831.27 and from Table 'V owectio Cr <br /> -- 127 ft. Or oee A--W and E is measured xi found W <br /> 42 ft. Whst is D? From Table IV E-230.9 and-x42=6.6 or D�w <br /> 50301. <br /> FIELD BOOK <br />