Eight-shaped wall, I-shaped wall (end wall type), twisted slope type, flat head type, corridor type, streamlined type and falling well type. Culvert is a drainage tunnel under subgrade, which usually consists of two parts: tunnel body and portal building. The tunnel body is composed of several pipe joints and is the main body of the culvert. Buried in subgrade, there is a certain longitudinal slope to facilitate drainage; The end wall and wing wall are located at the entrance, exit and both sides, which play the role of retaining soil and guiding water, and can also protect the embankment slope from water erosion.