DLZ provided inspection, survey and engineering services for the rehabilitation of the bridge carrying Main Street over St. Joseph River in Elkhart, Indiana. The existing Main Street Bridge over St. Joseph River was a three span (92’, 92’ and 92’) earth-filled reinforced concrete arch bridge with an asphalt wearing surface. The bridge carried five lanes of traffic with a clear roadway width of 60 feet.
The inspection of the Main Street Bridge included sounding all of the concrete in the spandrel walls, arch rings, piers, abutments and retaining walls for delaminations, spalls and other deterioration. The scope of the project included removing and replacing the existing curb, sidewalk and bridge railing, repairing the spandrel walls and arch rings with pneumatically placed mortar and sealing the arch and spandrel walls.
The scope also included milling and resurfacing the roadway and placing erosion control at the piers to prevent future scour at the bridge. The replacement of two existing water mains and a major fiber optic line were also included in this project. All work was performed while maintaining two lanes of traffic on the bridge.
Additionally, a hydraulic analysis of the existing bridge was performed using the U.S. Army Corps of Engineers HEC-RAS program. An existing hydraulic model of the St. Joseph River in Elkhart County was used as a starting point, and additional surveyed sections were added both upstream and downstream of the bridge to supplement the existing information. The existing model was also modified to include the scour holes that had formed at the piers.
The analysis included determining scour elevations at the bridge for the 100 and 500-year discharges and designing scour countermeasures to repair the existing scour holes at the piers and to prevent additional scour in the future. DLZ also prepared environmental permits for the Indiana Department of Natural Resources, the Indiana Department of Environmental Management and the U.S. Army Corps of Engineers.