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4. 7 s _ I <br /> DIETZGEN'S RAILROAD CURVE <br /> AND. <br /> REDUCTION TABLES <br /> COM'Asht,1914,by Eugem Dietsm Co.,New York CRY <br /> PG T P. <br /> d <br /> + <br /> I A <br /> C <br /> X <br /> CURVE FORMULAS <br /> Radius=R=s n.�(1)Degree of Curve=D and sin.)=x(2) <br /> Tangent=T=Rtan� (3)Length of Curve=L=100$(4) <br /> Middle ordinate=M=R(17-cos. (5) =Rvers (6) <br /> External=E=Ttan*-(7)=R+cos.#-R(9)-Rexsec#(9) <br /> Long Chord=C=2 R sin.s(10)�=Central Angle <br /> EXPLANATION AND USE OF TABLES <br /> Stations.-Given P. I.=Sta. 161+60.35 to find Sts. of P. C. <br /> and P. T. 0=62° 10' D--8°20'. From Table IV for 1* curve T= <br /> 3454.1 and+83J=414.49 ft. From Table V eorrection�,86 or T= <br /> 414.85 ft. P. C.==8ta. P.I.-T=157+45.50. : Also from (4) 1- <br /> 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 for Sta. <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-158-3ta.P. C.=54.50,hence <br /> offset=7.27 (54.50+100)2-2.16 ft. Also square of any dastame <br /> divided by twice the radius equals(approximately)the distance from <br /> tangent to curve. Thus (54.50)9+(2 x 688.262.16 ft. <br /> Deflections.-Deflection angle% D for 100 ft., .D for 50 ft., <br /> etc. <br /> For a ft.=(in minutes).3 x C x ll0`or�defl.for 1 it.from Table <br /> III x C. For Sta. 158 of above curves=.3 x 54.5 x 8136.2' or <br /> defle20 16.21,or�2.50 x 54.5=136.2'1rom Table III. For Eta. 159 <br /> c-tion.angle20160+80 20'+2=80 X6.2',etc. <br /> Externals.-May be fpund in kinfier manner to Ungents. Thus <br /> - E for curve above is 91.37 For from Table IV for 10 curve E=9W.6 <br /> for 80 20'=960.6+8Y8=L91.27 and from Table V correction-.10 or <br /> E=91.37 ft. Or suppose &­&and E is measured and found to be <br /> 42 ft. What is DY From Table iV.E-=?30.9 and+42-5.5 or D-. <br /> j50301. <br /> I <br />