Wisconsin & Southern Railroad Co. retained Ayres Associates to provide a comprehensive study and evaluation of a leased bridge near Merrimac. The structure is a 22-span, 1,729-foot-long open-deck truss/open-deck girder structure over the Wisconsin River.
Services included field survey and underwater contour mapping, underwater inspection with divers, structural steel superstructure inspection, load rating, risk analysis, cost estimating for alternatives, and public meeting presentations.
The underwater inspection was completed using surface-supplied air with two-way communication by divers who meet National Bridge Inspection Standards and are registered professional engineers. The above water portions of the structure were inspected using rock climbing and rope access techniques to provide fall protection as the inspectors moved across the structure. The bridge was also analyzed for its load-carrying capacity, and a Level 2 scour analysis was performed.
The final deliverable was a comprehensive report of the structure’s condition, the capacity of its members, and detailed repair recommendations.