This project involved the survey, design, and preparation of plans for the replacement of the deficient three-span concrete beam bridge on SR-31 in Union County, along with reconstruction of the approaches.
This structure acts as a northern gateway to downtown Marysville and the urban nature of its surroundings made drastic changes to roadway grades undesirable. The profile was raised slightly over the structure and tied back to the existing grade shortly outside the approach slab limits. Special aesthetic railing at the curb line, rather than standard barrier, was requested by the City of Marysville to accompany other landscaping improvements that were planned for this city entrance point. This railing was tapered away from the roadway outside the bridge limits to avoid the use of terminal assemblies, which the City felt would detract from the aesthetics. NCI designed a steel tube pedestrian fence system which further supported the City’s aesthetic vision. A detour route was prepared which allows the structure to be built in one stage and minimize construction duration. The waterline attached to the existing bridge was relocated to the west and run below Mill Creek.
The new bridge is a single-span, composite 54” steel plate girder structure with a span of 140’-0”. It has wall abutments which are supported by piles. A semi-integral design was chosen to eliminate deck joints and improve durability. The hydraulic study revealed a slightly shorter span would still pass the required storm events. Moving the abutments inward allowed the channel geometry to be improved and the flow path below the bridge was straightened. A scour analysis was performed and scour protection measures included increased pile length and rock channel protection.
CLIENT: ODOT District 6/The City of Marysville