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PICKA <br />!>a✓� <br />z — <br />//..04gza,6a <br />T <br />8 ' <br />;PR I <br />W P -A <br />30i� - <br />t, <br />6 <br />f Zo, o o <br />I Sid <br />f/ <br />) <br />D <br />v C <br />S �LsL <br />i <br />Z <br />7 8/ <br />1 <br />Ile TI -6 <br />o- <br />,o <br />soo <br />Z <br />. <br />/z•3s <br />137 <br />987 11 <br />Q zd, is <br />1 <br />C <br />y <br />1� <br />1 <br />C <br />i U <br />0+ <br />e <br />N <br />�� o, �3 <br />•ZS' <br />Pr 9is <br />F <br />CURVE AND: -REDUCTION ,TABLES <br />Published by Eugene Dietzgen Co. <br />CURVE FORMULAS <br />• 50 <br />w 1. Radius R'—sin 0 <br />I 50 <br />2. Degree of Curve: D= 1'00 L Also, sin D/2= R <br />Tforl°curve C <br />3. Tangent T=It tan % I. Also, T-- D + <br />4. Length of Curve: L=100 D <br />`5.. Long Chord L. C.= 2R, sin % I. <br />6. Middle Ordinate:. M= R (1—cos t/2 1) <br />7. External E= It —R• Also, E=T tan % I. <br />COS Y2 <br />EXPLANATION AND USE OF TABLES <br />Given P.I. Sta. 83 -40.7, I =45° 20' and D =6°30' find: <br />T for 1° Curve C From Tables V and Vi <br />stations—P. C, = P. I <br />i <br />T — <br />2395.8 +.197=3M.32=3+68.32. <br />.197=365.32=3+68.32. Sta. P. C.=83+40.7—(3+68.32)=79+72.38- <br />6.5 <br />P. T. =P. C.+L, and L =100 D =100 48:53 = 697.38 Therefore, P. T. =(79+72.38) <br />+(6+97.33) =86+69.76. <br />Offsets—Tangent offsets vary (approximately) di ectly with D and with the <br />square of the distance. From Table III Tangent offset for t00 feet =5.669 feet. Distance <br />^7'6214`"432 ft. Also, square of any <br />=So —Sts. P. C. -27.62. Hence offset =5.66 X (4100 1 <br />distance, divided by twice the radius equals (approximately) the distance from tangent <br />to curve. Thus (27.62)°=(2X881-05) =.432 ft. <br />Deflections—Defection angle =" D for 100 ft., y4 D for 50 ft., etc. For "X" ft., <br />Deflection Angle (in minutes) =.3 XX XD. For Sta. So of above curve Deflection Angle <br />]!!.flee <br />Xfi.5 =53.86'. Also Deflection Angle =dfl. for 1. ft. from Table III XX =1.95 <br />21-E =4° S.86'. <br />L 53.86'. For Sta. 181 Deflection Angle =53.86'+ <br />nala—From Table V for 1° curve, with central angle of 45° 20', E =479.6. <br />479.6, for 6° 30'curve, E = <br />6.5 h Correction from Tabic V f —7.379+.039 .039 =7.41 . <br />t 1 <br />