. The railroad engineer's practice . e curve H A to the point P, given by the follow-ing equation: R Cotan. \ A MP— — (cotan. ^ A NB + cotan. ^ a) — cotan | The curve from Pto B is, of course, found by measuring thetotal deflection angle, and dividing by the number of stations. Vv^e can, by means of this problem, connect two curves runningtoward each other with a third one. Let -4 and B be points onthe respective curves. We wish to continue the curve H A past^4 to some point, P, from which to run some third curve connect-ing with the other curve at B (the tangent B E being common tothe las
. The railroad engineer's practice . e curve H A to the point P, given by the follow-ing equation: R Cotan. \ A MP— — (cotan. ^ A NB + cotan. ^ a) — cotan | The curve from Pto B is, of course, found by measuring thetotal deflection angle, and dividing by the number of stations. Vv^e can, by means of this problem, connect two curves runningtoward each other with a third one. Let -4 and B be points onthe respective curves. We wish to continue the curve H A past^4 to some point, P, from which to run some third curve connect-ing with the other curve at B (the tangent B E being common tothe last two curves). Measure the angle G AB = ^ AN B; also the angle KB A —^ANB-Y a ; and the distance A B = 2 R sin. iANB. Thencalculate A M Pfrom. the above equation; dividing by the degreeof the curve H A gives the distance ^4 P in stations. FromP O P = .4 NB + a— .4 M Pand the distance P B, we canfind the degree of the curve P B. Problem 5. To change the radius of a curve so that it will comeout in a given tangent. A-< To change the radius of the curve E D so that it wUl come outin the tangent C H. Having rvm the curve until the tangent D Kis nearly parallel to C H, measm-e the offsets D G and / K, and the distance G I. , DG\Calculate G F and then a ( = fan. — - . We could also mea- Cr i* / sure this angle directly by measuring ofE M H = D G and takinga sight on M. Then AC = A B + B C = R ver. sin. a -\- D G. 13 We then find the new radius by Problem 1. A C E = R ± ver. sin. I ( I = the former total angle minus nr). Proolem 6. Having located a curve connecting two angents,it is required to move the middle of the curve any given distanceeither toward or from the vertex.
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