San Diego — Kleinfelder won the ACEC Honor Award for the Georgia Street Bridge Over University Avenue Rehabilitation and Seismic Retrofit project for the City of San Diego. The award was announced at the American Council of Engineering Companies (ACEC) California’s 2019 Engineering Excellence Awards Banquet in San Francisco, Calif.
Constructed in 1914, the Georgia Street Bridge has been an iconic gateway to San Diego’s North Park neighborhood for over a century. Over the years, the structure and its walls had undergone a substantial amount of repairs and modification, including extensive patching and multiple global layers of shotcrete. Degradation of the concrete and reinforcement was visually apparent despite the placement of many layers of shotcrete. In addition, the structures had several functional deficiencies including substandard barrier rails and sidewalks, vertical and horizontal bridge clearance, and inadequate to support for modern vehicular live loads.
As the lead consultant and bridge designer, Kleinfelder worked with the City of San Diego (Client/Owner) to develop a full retrofit plan as well as address other rehabilitation efforts for the bridge. The reconstruction plan was developed to alleviate structural deficiencies, seismic vulnerability and extensive deterioration.
Historic preservation of the bridge and retaining walls, as well as public safety, were the dominant factors in determining the retrofit strategy. Several communities and organizations in uptown San Diego that had stressed the importance of maintaining the bridge’s historic integrity were engaged during preliminary engineering, concept approval, environmental clearance, and final design. Kleinfelder worked with historic architects retained by the City during design development to optimize solutions for maintaining the historic value of the structures.
Squeezing a modern seismic design into the framework of a historic arch bridge, along with working in a confined environment that had to maintain the continuity of traffic flow, was no easy feat. Unique design considerations had to be applied in order to preserve the historic integrity of the bridge while bringing it up to current safety and seismic standards. To accomplish this, Kleinfelder utilized innovative techniques including integration of existing arch ribs into the final structural system, hydrodemolition of cover concrete, and self-consolidating concrete with reinforcing fibers. Kleinfelder provided the City with an innovative design that balanced safety, historic preservation, cost, and seismic performance, while accomplishing the goal of revitalizing an iconic structure.
In addition, Kleinfelder continued to be involved throughout the construction process, adjusting the requirements as various issues emerged, as is to be expected when deconstructing and rebuilding a 100-year-old structure. Working closely with the City and contractor, Kleinfelder ensured that the project requirements were met while balancing the schedule and costs, and ultimately restored the aging landmark to its original glory.