Bridge 207 is a single-span (112’) Pratt Through-Truss steel bridge that carries O’Neal Road over Big Eagle Creek. The bridge originally had a timber plank deck and the steel superstructure was supported on a steel caisson abutment and a concrete wall-type abutment. According to the available records, this steel truss bridge was originally built around 1900.
At the start of this project, the truss bridge had a 3-ton load limit posted. However, the significant deterioration observed on several steel members below the deck made it necessary for Boone County to close the bridge to all vehicular traffic.
Lochmueller Group (Lochgroup) prepared comprehensive bridge restoration plans, specifications, and bid documents. Since original bridge plans could not be located, the rehabilitation included a detailed field inspection and survey to measure the existing bridge framing components and dimensions and to document the existing structural conditions. Restoration plans detailed removal of superstructure members with insufficient load-carrying capacity and replacement with new, high-strength steel members that matched the appearance of the original members. The removal and replacement of these select components increased the load-carrying capacity of the bridge and allowed the county to remove all load-limit postings.
The plans also detailed repairs to damaged bridge components and sections of the bridge railing with replacement pieces closely matching the original appearance. The existing timber plank deck was replaced with a new timber deck capable of supporting the higher vehicular load demands. Project specifications further detailed a full cleaning and repainting of the entire steel truss structure to lengthen the life of the bridge.
Following the completion of the bridge rehabilitation design, Boone County retained Lochgroup to provide construction engineering services. These services included shop drawing reviews and periodic site visits to observe and review construction efforts.