Assembled highway steel bridge was first designed by English engineer Donald Bailey in 1938, i.e. the beginning of World War II, so it is also called Bailey bridge.

Bailey bridge is built with two pieces of main trusses with a beam in between. Above the beam are stringer and bridge plate. The beam is fixed with bracing and tying materials. The bridge plate is made of wood and all the other parts are made of steel, so it is also called steel structure bridge. The main trusses can be parallel in single, double or three rows and can also be double or three layers so as to increase the bearing capacity. Such kind of Bailey bridge can also be built into suspension bridge, floating bridge or railway bridge. Due to its steel structure modularization design, Bailey bridge has excellent exchangeable connection performance. It can be either longer or shorter, wider or narrower. Furthermore, it is quick to build a Bailey bridge. Due to its economical efficiency and convenience, Bailey bridges are used by many countries to build temporal bridges or semi-permanent bridges. Its purpose has been expanded from purely military field to civil highway bridge. Bailey bridges have been widely welcomed by users since it came into being.

During World War II, a large number of assembled highway steel bridge was used in rush  repair of bridges and erecting of temporary bridges in European and far east batter fields. In 1941, USA purchased patent from England to manufacture assembled steel bridge, which was named as M1 steel bridge. After improvement (the carriageway is widened by 12%), it was named as M2 steel bridge. After World War II, many countries introduced assembled steel bridge and began to use them for civil purpose widely. In China, assembled steel bridges also made great progress and began to be modeled and manufactured in 1965. Nowadays, assembled steel bridges are widely used in national defence, traffic projects, public works and hydraulic engineering.