Culvert

A culvert is a structure that channels water past an obstacle, most often carrying a stream or drainage flow underneath a road, railway, or other embankment so that the crossing can carry traffic while the water continues to flow beneath it. Culverts are typically buried in the surrounding soil or fill and are built from materials such as concrete, corrugated steel, or plastic pipe, in shapes ranging from simple round pipes to elliptical, box, and pear-shaped designs chosen to suit the site's hydraulic needs; beyond road crossings, culverts also relieve roadside drainage ditches and can carry fire hoses beneath noise barriers. Because poorly sized or poorly installed culverts can obstruct fish and other aquatic wildlife from moving along a stream, restoring a culverted stream to open air, called daylighting or deculverting, has become an increasingly common environmental practice. No single clean origin date or inventor is established in the source consulted, since culverts developed gradually as a standard element of road and drainage engineering.