1833

A vertical parabolic sag curve is to be designed to connect a down-gradient of 1 in 20 with an up-gradient of 1 in 15, the chainage and reduced level of the intersection point of the two gradients being 797.7 m and 83.544 m respectively. In order to allow for necessary headroom, the reduced level of the curve at chainage 788.7 m on the down-gradient side of the intersection point is to be 85.044 m. Calculate:(a) The reduced levels and chainages of the tangent points and the lowest point on the curve.(b) The reduced levels of the first two pegs on the curve, the pegs being set at the 30-m points of through chainage.