On-site Assembly And Erection Of Bailey Steel Bridge (Core Process)

This is the key stage that demonstrates the "rapidity" characteristic of Bailey bridges, typically employing the cantilever launching method.

Assembling the Truss on the Ground:
On a leveled area behind the bridge abutment, individual Bailey panels are connected using pins to form double-row, single-layer truss segments. Every two panels are paired side-by-side and linked via crossbeam frames and sway bracing, creating a stable portal frame structure.

Embodiment of the "Reinforced" Design: During this process, strengthening chord members are installed at the top and bottom chord positions of the main truss and secured with dedicated chord bolts, thereby enhancing the load-bearing capacity of the entire truss.

Installing the Launching Nose (Leading Edge):
A lightweight, triangular launching nose is assembled at the very front of the bridge. This nose serves for guidance and load distribution, reducing the bending moment during the cantilever launching process.

Launching and Erection:
Using a winch, crane, or manual capstan as the power source, the assembled bridge structure is progressively pushed from the bank toward the opposite shore. As the bridge advances forward, new truss segments are continuously added at the rear, along with the installation of crossbeams and decking. This is a dynamic balancing process requiring careful control of speed and center of gravity.

Positioning and Lowering the Bridge: Once the launching nose reaches the far bank abutment, precise alignment is performed. Using equipment such as hydraulic jacks, the entire bridge is lowered onto the pre-set bearings.

Installing Ancillary Structures: End posts, guardrails, final deck fastening, and expansion joint treatments are installed.