Bridge height: referred to as bridge distance, refers to the height difference between the bridge deck and the low water level or the distance between the bridge deck and the road surface under the bridge. The bridge height reflects the difficulty of bridge construction to some extent. The width of the bridge is the clearance of the bridge deck. In order to ensure the safe passage of vehicles and pedestrians, the boundary space should be reserved above the bridge deck perpendicular to the driving direction. It includes the clear width and clear height of the bridge deck. The total length of the bridge. For bridges with abutments, it is the distance between the side walls or the ends of the splayed walls on both sides of the abutments. For bridges without abutments, it is the length of the bridge deck.