Hampden Bridge is a three span, overhead brace Allan Timber Truss Bridge. Spanning the Murrumbidgee River, the Hampden Bridge once provided the main link between north and south Wagga Wagga, but was replaced in 1995 with the Wiradjuri bridge 150 metres downstream.
The main spans of Hampden Bridge consist of three 33.6m span 6.4m deep Allan trusses on cylindrical iron piers. The carriageway measures 7.39m wide with a 1.37m wide pedestrian walkway. The walkway is located on the upstream side of the bridge.
The Hampden Bridge is a modified "Allan truss" type timber structure using sloping and top chord timbers as compression members and vertical steel rods as tension members. The bottom hardwood chords of the trusses are tension members. The tops of the trusses are tied together and braced by horizontal timber struts and steel rod horizontal bracing. Node points for trusses comprise custom fabricated cast iron bolted joints.
The decking comprises a bitumen wearing surface on heavy plywood with hardwood stringers supported at intervals corresponding to the truss nodes by heavy hardwood cross beams supported in turn at each end by the bottom chord of the trusses on each side of the bridge.
The bridge is supported by two steel towers founded in the Murrumbidgee River, one steel stub tower at the eastern abutment and by a concrete wall at the western abutment. The tower foundations are unknown being concealed below water level but believed to comprise steel tower tubes continuing below water level into concrete filled steel caissons probably to rock.
The bitumen wearing surface and plywood decking of the road deck are carried by heavy log hardwood stringers spanning up to eight metres onto hardwood cross beams, the cross beam supported in turn by a series of closely spaced cross braced hardwood poles founded on the natural ground using hardwood sole plate or spreader. Some larger span stringers have retrofitted log props to reduce their effective span.