The vertical alignment of highway generally defined as the presence of heights and depths in vertical axis with respect to horizontal axis of alignment. These heights and depths in roads may be in the form of gradients (straight lines in a vertical plane) or vertical curves.

Raise with respect to horizontal distance is called Upward gradient (+n %)

Fall with respect to Horizontal distance is called Downward Gradient (-n %)

A detailed explanation of how vertical alignment is implemented in MicroStation and InRoads is presented in the following video.