The superstructure of a Cambridge Steel Truss Bridges is made up of the two truss structures on the sides of the bridge. Despite the trusses being composed of discrete members (arranged to form triangles) that are subjected primarily to axial loads, the two trusses generally react like two large support beams. Floorbeams are attached to the truss and run perpendicular to the flow of traffic to support the bridge loads that are distributed by stringers that run parallel with the flow of traffic. The top and bottom members of the truss system, chords, are often attached laterally to provide stiffness and resistance to wind loads. For the Cambridge Steel Truss Bridge, the top chords are generally arched.
This type of Truss System is installed along the sides of the bridge deck with floorbeams connecting the bottom chords to support the deck. This type of superstructure can support bridges of varying spans.
The members to be assembled are lighter for a truss system than those used for rolled steel girders and plate steel girders. There are of course several more members to be assembled in a truss system than in other superstructure methods. Because of the lighter member size, smaller cranes can be used in the construction process. The elements are connected to one another using bolted connections. For simple span trusses, falsework towers are usually required to facilitate erection. For continuous trusses, a cantilever erection can be used using falsework towers near the interior piers.