T.Y. Lin International

Scope Of Work

T.Y. Lin International (TYLI) was selected by the California Department of Transportation to upgrade the historic Laurel Street Overcrossing in San Diego, California, to current earthquake safety standards. The overcrossing, also known as the Cabrillo Bridge, carries vehicles, pedestrians, and bicyclists and is a vital link across State Route 163 and Cabrillo Canyon into Balboa Park, one of the San Diego’s main visitor destinations.

The 769-foot-long Laurel Street Overcrossing was built in 1915 and is a reinforced concrete cantilevered hollow arch structure with a maximum height of 129 feet. Retrofitting for seismic strength and rehabilitation was required due to corroded steel and unsound concrete. Resembling a Roman aqueduct, the bridge is listed on the National Register of Historic Places, which made preservation of its historic character a controlling design criterion.

TYLI’s scope of work included performing detailed inspections; determining the scope and cost of necessary rehabilitation work; developing the seismic retrofit strategy; preparing final plans, specifications, and estimate (PS&E); and providing support during construction for both the rehabilitation and seismic retrofit.

PROJECT HIGHLIGHTS:

TYLI's seismic retrofit strategy used both response-spectrum and non-linear time history analyses.

The bridge's historic character was preserved by concealing all retrofitting within the internal framework.

The superstructure uses external post-tensioning for seismic stability.

Pedestrian access was maintained at all times during construction.

Bridge closure to traffic was limited to a short, four-month window.

To facilitate bridge inspection access, TYLI designed interior, OSHA-compliant catwalks and ladders, upgraded the electrical system, and added lighting.