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I i 6ELDBOOK 3 DIETZGEN'S RAILROAD CURVE 1 _ AND REDUCTION TABLES Cbyp tight,1914,by Eugene Dietftm Co.,New York CIO TT PacA �w 41 CURVE FORMULAS Radius=R=e-�(1)Degree of Curve=D and sin.D=x(2) Tangent=T=Rtan"" (3)Length of Curve=L=100 4 Middle ordinate=M=R(1—cos. (5) =Rvere 3(6) External=E=Ttanr(7)=R=cos. -R(8)=Rexsec4(9) Long Chord=C=2 R sin.q(10),&=Central Angie EXPLANATION AND USE OF TABLES Stations.—Given P. I.==Sta. 161+60.35 to find Sta. of p. C. and P.T. 0 62° 10' D-80 20'. From Table IV for P curve T- 3454.1 and+8�J=2 49 ft. From Table V oorra tion�,36 or T ! 414.85 ft. P. CSt 6 P.I.—'D=157+45.50. Also from (4) 1. i 746.00 and P.T.oBta.P.C.+1,--164+91.50. d 4 Oflseter—Tangent offsets vary (appppro�rimately) directly with D and with square of the distance. Rus tangent offset for 8ta. 158 55 ofour,100 ft curve7�7 6gtft.found follows. From Table III tangent offset ce=1 b8—Stn.P. C.=54.50,hence offset-7.27 (54.50+100?--2.16 ft. Also are of any divided by twice the radius equals(I proximately).the disttancef distance tangent to curve. Thus (54.50)'+(2 x 688.26}=2.16 ft. C Deflections.--Deflection angbe= D for 100 ft., 7,�D for 50 ft., etc. For c.ft.=(in minutes) 3 xC X. etc. or=-lefl.for 1-tt.from Table ! III x C. For Sta. 158 of above curve—.3 x 54.5 x 83J-136.2' for 20 16.2,or-2.50 x 54.5=136.2'from Table III. For Sta. 159 deflec- tion angle"16.2'+W 20'+2==("26,2',etc. ( Externllpj--May bund in similar manner to tangents. Thus E for curve above is 912For from Table IV for r curve E==960.6 for 8° 2 —4W.6+8H=-91.27 and from Table V correction=.10 or I E=91.87 ft. Or suppose o-32°and E is measured and found to be 42 ft. What is DY From Table IV E—L30.9 and+42,5,5 or D-- 50301.