Terms used in this chapter mean:
(1) "Bridge," a structure, including supports, erected over a depression or an obstruction, as water, highway, or railway, the structure having a length measured along the center of the roadway of more than twenty feet between undercopings of abutments or extreme ends of openings for multiple boxes and pipes where the clear distance between openings is less than half of the smaller contiguous opening;
(2) "Culvert," any structure not classified as a bridge which provides an opening under any roadway;
(3) "Department," the Department of Transportation.