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STlC ac✓ �� t <br /> q ✓i"r Tim v, J�r� . <br /> -- ! DIETZGEN'S RAILROAD CURVE <br /> AND <br /> i <br /> REDUCTION TABLES ! <br /> ODIVriebt.1914,by Eugene Diet:<en Co.,New York qty <br /> ' P.ne <br /> S F <br /> R2 CURVE FOR11,1ULAS <br /> i Radius=R= 50 (1)Degree of Curve=D and sin.P=Lo('2) <br /> , <br /> Tangent=T=Rtan"j' (3)Length of Curve=L=100j(4) <br /> Middle ordinate=M=R(1-cos. (5) =Rvers (6) <br /> External=E--Tian (7)=R+cos.4L R(8)=Rexsee#(9) <br /> r <br /> "s',._ Long Cbord=C=2.R sin.y(10),&=Central Angle <br /> EXPLANATION AND USF- OF TABLES <br /> S' Stations.-Given P.,I.=-Sta. 161+60.35 to find Sta. of P. C. <br /> and P. T. 0-620 10' D=-r 2d. From Table IV for 1° curve T- <br /> 3454.1 and+8A==414-49 ft. From Table V correction-6$6 or T <br /> r 414.85 ft. P. C.= S* P.1.-T-157+45.50. Also from (4) L= <br /> 746.00 and P.T.-Sta.P.C.+D-164+91.50. <br /> 1` Offsets.-Tangent offsets vary (appro�nmstely) directly with. <br /> D and with square of the distance. Thus tangent offset for 88ta. <br /> 2 (: 158 on above curve is 2.16 ft.found as follows. From Table III tangent- <br /> offset <br /> angentoffset for 100 ft.=7.27 it. Distance-15&-,Sts.P. C.=�-54.50,hence <br /> offseta7.27 (54.50+100)2a2.16 ft. Also square of ally "distance <br /> divided by twice the radius equals(approximately)the distance from <br /> tangent to curve. Thus (54.50)2+(2x688.26)--2.16 ft. <br /> 4 Deflections.-Deflection anglp=34 D for 100 ft., V4 D for 50 ft., <br /> etc. For a ft.=(in minutes).3 x C x D or�lefl.for 1 ft.from Table <br /> -= IIlr x C. For Sta. 158 of above curve-.3 x 54.5 x 8 =136.2' or <br /> 2° 16.2',or--2.50 x 54.5 136.2'from Table III. For Sts. 159 de$ec- <br /> 5 8 I ! tion angle=2°16.2'+8°20'+2-P 26.2',eta <br /> Externals.-May:be found in similar manner to tangents Thus <br /> E for curve above is 91.37. For from Table IV for 1!curve F--960.6 <br /> j for 8° 201=60.6+8yj=-91.27 and from Table V correction--.10 or <br /> E---91.37 ft. Or suppose p==32°and E is measured and found to be <br /> I� 42 ft. What is DY From Table IV Fo- 3 .9 and+42=5.5 or D= <br /> 4 ,`i i) � j o 0 5°301• <br /> .p. - <br />