What is the meaning of bridge span (5×20)+(4×20)m? How to know the distance between piers and the length of the bridge?

The bridge consists of 9-hole and 20-meter-span beams or slabs, with two joints, one with 5 holes and the other with 4 holes. Pier spacing generally refers to the distance between the center lines of two piers. There are several concepts of bridge length, such as single span, multi-span and standard span. Generally, the length of a bridge with abutment refers to the distance between the back ends of two abutment side walls or splayed walls; The bridge without abutment is the length of deck system. See General Code for Design of Highway Bridges and Culverts for details.