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FIELD B OK 5 <br /> DIETZGEN'S RAILROAD CURVE <br /> AND <br /> REDUCTION TABLES <br /> Ci wzUht,1914.by Eugene Dietw.Co..New York C by i <br /> TN)e <br /> 41,4 <br /> 9- <br /> CURVE FORMULAS <br /> Rediae=R= 80 (1) Degree of Curve=D and sin. -be(2 <br /> G @,—. / PHIL <br /> Tangent=T=Rtan6 (3)Length of Curve=L=1 0(4) f <br /> ' -- ids/ Middle ordinate=M=R(1—cos. ly�')(5) =Rvers A(6) <br /> y 39- <br /> J,J, o , External=F_=Tfan"--M=R=cos.#-R(8)=Rexaee#(9) <br /> o a r - Long Chord=C=2 R sin.8(10)A=Central Angle <br /> sra d EXPLANATION AND USE OF TABLES <br /> Stations.—Given P. I.---Sta. 161+60.35 to find Sta. of P. C. <br /> and P.T. p==62° 10' D---W 20'. From Table IV for 1• curve T= <br /> s 8454.1 and-e•8a414.49 ft. From Table V correction=.36 or T- <br /> 414.85 ft. P. C.�Sta. P.I.—T=157+45.50. Also from (4) La <br /> 746.00 and P.T.=Sta.P.C.+Ir=164+91.50. <br /> Offsets.—Tangent offsets 'vary (approximately) directly with <br /> D and with square of the distance. Thus tangent offset for Sts. <br /> 158 on above curve is 2.16 ft.found as follows. From Table III tangent, <br /> offset for 100 ft.-7.27 ft. Distance=158—Sta.P. C.s54.50,Bence <br /> offset-7.27 (54.50+100)2=2.16 ft.pAlso square of an distance <br /> l t agent too di Red by twice the radius curve. Thus (54.50)2+uals (2 x 6M.28��2?18 f distance <br /> ce from <br /> DeSecdons.—Deflection angle= D'for 100 ft., D for 50,ft., <br /> s�s etc. For o ft.�(in minutes .3 x C x T)°ox deft.fos lL from Table <br /> III x C. For Sts. 158 of)above curve=.8 x 54.5 x 83j-136.2' or <br /> I-A`w 2° 16.21,or--2.50 x 54.5=136.2'from Table III. For Ste. 159 deflec- <br /> tion angle=2°16.2'+80 20'-i-2=-V 26.21,etc. <br /> Externals.—May be found in similar manner to tangents. Thus <br /> E for curve above is 91.37. For from Table IV for P curve E-980.6 <br /> for 81 201=960.6+83§ 1.27 and from Table V correctioamm.10 or <br /> E=91.87 ft. Or suppose o-32°and E is measured and found to be <br /> 42 ft. What is DY From Table IV E=230.9 and+42=4.5.or Da. <br /> 5°30'. <br /> t ' <br /> V <br />