VERTICAL ALIGNMENT

Vertical alignment is the rise or fall of the curves in a highway. Similar with horizontal alignment or the curving to the left or right of the highway curve, the critical parameter for this alignment is the sight distance - stopping and overtaking.

The only difference with the relation of sight distance with the length of the curve is the number of cases where

1. S>L
2. S<L where        S = sight distance and L = length of curve

The two kinds of vertical curves are:

1. Summit (aka, crest curve, and oververticals) = curve which concaves upwards

2. Valley (aka, sag curve, and underverticals)   = curve which convexes upwards.

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