In civil engineering, the invert level is the base interior level of a pipe, trench or tunnel; it can be considered the `floor` level. Conversely, the crown level is the highest interior level, and can be considered the `ceiling` level. ... Found on http://en.wikipedia.org/wiki/Invert_level
In civil engineering, the invert level is the base interior level of a pipe, trench or tunnel; it can be considered the `floor` level. Conversely, the crown level is the highest interior level, and can be considered the `ceiling` level. ...