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DIETZGEN'S RAILROAD CURVE <br /> AND <br /> REDUCTION TABLES <br /> I COWAAt,1914,by Eugene Dietigen Co.,New York Chy <br /> Pn,ej <br /> f ; CURVE-FORMULAS <br /> Rsdiue_R._ b0O�{ 1 Degree L <br /> s n�Ia of Curve=D and sin.a—s <br /> Tangent=T=Rtan6 (3)Length of Curve=L=100 (4) <br /> Middle ordinate=M=R(1—cos. 1)(5) =Rversy(6) <br /> I + Ezternsl-E=Ttan`-(7)=R=cos.g R(8)=Rexaec.$(9) <br /> T� �• t "r-- Long Chord=1b=2 R sin.z( 10)O=Central Angle <br /> � EXPLANATION AND USE OF TABLES <br /> i 8tttions.--Given P. I.=Sta. 161+60.35 to find Sta. of P. C. <br /> and P. T. A=62° 10' D=8°20'. From Table IV for 1° curve T— <br /> '�<S 3454.1 and+8h=-414.49 ft. From Table V correction=.36 or T. <br /> 414.85 ft. P. C.=Sta. P.L—T=157+45.50. Also from (4) L= <br /> t 746.00 and P.T.—Sta.P.C.+L-164+91.50. <br /> Offsets.—Tangent offsets vary (a roximately) directly with <br /> D and with square of the distance. Thus tangent offset fpr Sta. <br /> ft <br /> 158 on above curve is 2.16 .found as follows. From Table III tangent <br /> offset for 100 ft.=7.27 ft. Distance=158—Sta.P. C.=54.50 hence <br /> offset=7.27 (54.50 �-100p=2.16 f( Also uare of an distance <br /> divided b twice the radius y <br /> - y equals appproximately)the distance from <br /> tangent to.curve. Thus (54.60p+(2x688:262.16 ft. <br /> DeSectioas.Deflection angl���tt D for 100 ft:, 3/D for 50 ft., <br /> etc. For c ft.=(in minutes).3 x C x 15°or�iefl.for it.fro Table <br /> / III x C. For Sta. 158 of above curve=.3 x"o x 8�§=136.2' or <br /> �� 2° 16.2,or=2.50 z 54.bc138.2'from Table III. For 8t 159'de6ec- <br /> tion angle= 16.2'+8'20'+-.26:2',etc. <br /> Externals.—May be found in similar manner to tangents. Thus' <br /> f E for curve above is 91.37. For from Table IV for 14 curve Ek-W.6 <br /> for 8° 20'=60.6+8h=91.27 and from Table V aorrecdon...10 or <br /> i E-91.37 ft. Or Appose &==W and E is measured and found to be <br /> { - 42 ft. What is D? Fwm Tabs IV E—M-9 and+42=5.5 or D= <br /> Fl LD 0,`1 07 6 3a. <br /> i <br />