Vertical adjustment potential example and factor of safety for various types of substrate.

A graph depicting a longitudinal profile of a stream with an existing culvert shown in dashed lines and a new culvert shown in solid lines. The longitudinal profile shows the existing thalweg, the existing water surface, the lower VAP line, the lower potential grade control line, and the existing crossing grade control line. The vertical axis of the graph shows the relative elevation in feet and the horizontal axis of the graph shows the distance downstream in feet. The new culvert is positioned so that the lower VAP line is higher than the invert of the new culvert.