Under this On-Call Civil Engineering Contract for the City of Suffolk, Clark Nexsen was responsible for providing engineering services primarily associated with the design and preparation of plans and specifications for construction of bridge design, road improvements/ extensions, parking lots, sidewalks, multi-use trails, stormwater facility extensions/ improvements, traffic signal design, traffic signal coordination time plan preparation, as well as various engineering studies to include traffic impact analysis, hydraulic analysis, stormwater master planning, environmental studies and capital improvement plan cost analysis. Services also include development plan review, preparation of permits, surveys, geotechnical assistance, construction inspection, grant applications, and other documents. Acceptance inspections were performed upon completion of construction.
Summary Scope of Work. Relevant projects completed under this contract include preparing preliminary and final bridge and approach roadway plans to replace three (3) single span high maintenance steel bridge structures crossing freshwater creeks. Structures include:
- Badger Road Bridge Replacement
- Simon Drive Bridge Replacement
- Southwestern Boulevard Bridge Replacement
Design Approach. The existing bridges experienced frequent overtopping during flood events, including the 10-year design storm. The proposed structures consisted of a 54’ single span prestressed concrete voided slab superstructure with an asphalt overlay supported on abutments utilizing a single row of prestressed concrete piles. The same span configuration and structure type was selected for all three structures to provide design, fabrication, and construction efficiencies.
The longer span configuration was designed to maximize the channel opening and allow for optimum hydraulic conditions. It was also advantageous in that it allowed the contractor to install the new piles and abutment cap prior to removal of the existing bridge, which effectively eliminated the need for temporary shoring to retain the waterway.