St. Bernard HMP Con Span Bridges
St. Bernard Parish, Louisiana
St. Bernard Parish Government
Project Overview
The St. Bernard HMP Con Span Bridge replacement program removed and replaced over nine bridges in St. Bernard Parish. The program consisted of engineering and construction administration services for the replacement of damaged or deficient canal crossings located throughout St. Bernard Parish. The initiative is part of the Parish’s investment in bringing their roadways, bridges, culverts or other canal crossing structures, and all associated infrastructure to meet current codes and standards, as well as providing hazard mitigation measures for structures prone to repeated damages caused by high velocity flood waters, sediment, and debris delivered by hurricane storm surges. The bridge scope included a full replacement of the existing drainage system. Royal performed an analysis of existing conditions and identified significant damages to the pipe ends as well as pipe breakage. These damages exacerbated existing subsidence, pipe separation, loss of hydraulic capacity, and roadway failure.
Project Work and Royal Solutions
Due to the extent of the damages documented by the Royal team, the project was deemed eligible for replacement by FEMA. Royal also conducted a cost analysis that ultimately justified a Hazard Mitigation solution (Con Span Hazard Mitigation) to replace the existing crossing with a lower-cost, resilient system that exceeded the existing hydraulic capacity of the canal. The Con Span Hazard Mitigation alternative for the Magistrate Street Bridge replacement was determined as eligible, resulting in a FEMA-obligated scope and cost.
To begin the project, Royal designed the interior height of the crossing to provide the cross-sectional area required for the drainage and engineered the roadway grades to raise the roadway while simultaneously not exceeding the maximum longitudinal slope required by LADOTD. In addition, Royal designed vertical curves into the changes in the roadway profile to provide a seamless transition from the new to pre-existing roadway grade. Next, Royal performed a complete hydraulic analysis of the existing canal and clear-span concrete arch that was constructed.
Elements of work included demolition and removal of the existing canal crossing, replacing the existing canal crossing with a precast concrete clear span con-span, driven timber and concrete piles, structural concrete grade beams, storm drainage, sanitary sewer replacement, waterline replacement, canal cleaning/shaping, riprap with flowable fill, roadway replacement, ADA ramps, sidewalks, and incidental PCC pavement.
Royal managed all elements of construction, providing the client with on-site representation, RFI, submittal, pay applications, and other construction administrative duties. As Royal managed several of these similarly scoped projects in succession, we were able to use lessons learned from past projects and implement changes in future projects. By constantly evaluating and evolving project plans and specifications, we were able to provide the client with seamless designs, specifications, bid packages, and a successful construction phase.
