Summit Curves in road

It is vertical curves with upwards gradient. They are formed when two gradients meet as illustrated in any of the following four ways:

1) When a positive gradient meets another positive gradient(fig a).

2) When a positive gradient meets a flat gradient(fig b).

3) When an ascending gradient meets a descending gradient(fig c).

4) When a descending gradient meets another descending gradient(fig d).

Types of summit Curve:

A) The common practice has been to use parabolic curves in summit curves. This is primarily because of the ease with it can be laid out as well as allowing a comfortable transition from one gradient to another.

B) Circular curve offers equal sight distance at every point on the curve, for very small deviation angles a circular curve and parabolic curves are almost congruent.