The culvert flowline slope is the average drop in elevation per foot of length along the culvert. For example, if the culvert flowline drops 1 foot in a length of 100 feet, then the culvert flowline slope is 0.01 feet per foot. Culvert flowline slopes are sometimes expressed in percent. A slope of 0.01 feet per foot is the same as a one percent slope.
The culvert slope is computed from the upstream invert elevation, the downstream invert elevation, and the culvert length. The following equation is used to compute the culvert slope:
