Wolf River Pedestrian Bridge
The Wolf River Pedestrian Bridge is a beautiful amenity at Shelby Farms Park that connects trail systems in the Park with the Wolf River Greenway and adjacent neighborhoods. The bridge is part of the ever-expanding network of connections linking visitors to Shelby Farms Greenline, which connects to Midtown Memphis. The 200-foot long pedestrian and cycling bridge features a steel-truss span and 12-foot custom wood decking that shapes the views that walkers, cyclists and others will get as they cross the Wolf River. The strategic design serves to dramatize the experience of entering the Park. The bridge connects not only with paved trails, but the primitive trails through the forest in the Lucius Birch State Natural Area.
SSR worked as a sub-consultant to Quality Iron to design the bridge. A major engineering challenge for the design of this huge structure was the planning for the actual, physical construction of the bridge. Two cranes were utilized to lift this massive structure into place and splice the trusses together over the Wolf River. This resulted in the splice being at the mid-span of the bridge. It was an engineering challenge to design a splice capable of withstanding very large forces and still have a simple connection that was easily installed while two cranes supported the half bridges.
To design the 250,000 pound bridge, a finite element model was utilized for comparison with traditional methods. The bridge was designed for specified vertical and lateral loads with adherence to AASHTO’s LRFD Guide Specification for the Design of Pedestrian Bridges (Dec. 2009). The superstructure of the bridge is composed of HSS members made from weathering steel material. An interesting fact is that the structure actually corrodes to protect itself. The 200 foot trusses were formed by shorter members that were welded together with complete joint penetration welds. The splice has four plates on the inside face of the HSS that slide inside the adjacent members. All bolts were high-strength A490 type three bolts.
SSR’s role was to provide the structural engineering for the bridge superstructure. This involved the design of the main trusses, the lateral bracing, and the bearing connections for specified loading conditions. The project had a construction cost of $1.27 million and the bridge opened to the public in December of 2010. The project won the 2011 Memphis City Engineer’s Award of Excellence as well as the 2011 TSPE People’s Choice Award in the Engineering as Art competition.