Number of PI Points
The Profile Grade is specified by PI points and the vertical curve data. Normally, a minimum of 5 PI points and three curve data are required to describe a vertical curve which contains a sag point and two crest points. . The program can not handle the case with one sag and one crest. If user is sure there is no water coming from the missing crest, a dummy crest with C=0 at the crest area should be specified. But for bridge cases, user can specify minimum of 2 points for a straight sloped bridge. Also possible for bridge case is a sag bridge, a crest bridge. PI points should be arranged from lower station to higher station. Each PI point requires station and elevation data. Maximum of 100 points can be specified. Note: when user choose curve fitting to input vertical curve, the total number of data points should be input in this field.