Laserfiche WebLink
FIE D BOOK 443 I <br /> IMPROVED TABLES <br /> AND <br /> INFORMATION <br /> TION <br /> T A <br /> ONC <br /> I <br /> CURVE FORMULAS <br /> Radi <br /> us_­ ,�,D (1) Degree of Curve=D and in. z—a(2) <br /> jTangent=T=Rtan s( 3) Length of Cur,,,--100°—n(4) ! <br /> Middle ordinate=M=R(I-=cos.�) (5)=Rvers a (6) <br /> Extern&I—F—Ttan*(7)=R=ccq-A—R(8)=Rexsec (9) <br /> Long Chord—C-2 R d..2(10) Amential Angle <br /> EXPLANATION ,AND USE OF TABLES <br /> X0 Stations.—Given P. I.—Sta. 161-1-60.35 to find Sta. of P. C. <br /> a and P. T. A-62° 10' Dom° 20'. 'From Table IV for P curve T— <br /> 3454.1 and=834=414.49 ft. From Table V correction=36 or T- <br /> 414.85 ft. P. C.=Sta. P.I.—T-157 -1-45.50. Also from (4) L <br /> 746.00 and P.T.=Sta.P. C.+L=164-x-91.50. <br /> Offsets.—Tangent offsets vary (approximately) 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—Sta. P. C.=54.50 hence <br /> ` t" 4. offset-7.27 (54-50—100) 2.16 ft. Also square of any distance <br /> divided by twice the radius a uals (approximately) <br /> tangent to curve. Thus(54.502-( 68ft. distance from <br /> Deflections.—Deflection angle=% D for 100 ft. for <br /> etc. For c ft.=(in minutes) .3 x C x D°or--deft,for f.Df from Table <br /> III x'C. For Sta. 158 of above curve—.3 x 54.5 x 8%=136.2' or <br /> 20 16.21,or=2.50 x 54.5=136.2'from Table III. For Sta. 159 deflec- <br /> tion angle--2o 16.2' +8°20' =2==6°26.2',etc. <br /> Externals.—May be found in similar manner to tangents. Thus <br /> - E for curve above is 115.37. For from Table IV for 1 curve E-960.6 <br /> for 8° 20'=960,6-8A=115.27 and from Table V correction=-10 or <br /> E=115.37 ft. Or suppose A=32°and E is measured and found to be <br /> 42 ft. What is D? From Table IV E=230.9 and -42=5.5 or D_- <br /> 50 301. <br />