Culvert
From BAWiki
Definition
Crossing structure for the passage of a water body, mostly with free water level, eg. through a dam. Junction structure in which a body of water, usually with free water level and significant narrowing of the outflow cross section, is passed through a dam. In a combination of underpass and culvert the greater importance is decisive for the assignment. If a footpath is a component of the culvert it becomes part of the object.