Culvert: a small drainage and flood discharge structure across subgrade or embankment. Culverts can be called culverts in a broad sense, including small water-passing structures such as open channels and inverted siphons. Culverts generally use single or double holes (rarely more than four holes). Culverts are generally built by excavation. Culverts are mainly composed of tunnel body, end wall or wing wall and imported paving.