T.Y. Lin International (TYLI), a globally recognized full-service infrastructure consulting firm, announces that May 30, 2015 marks the completion of the newly-rehabilitated Laurel Street Overcrossing at SR-163, also known as the Cabrillo Bridge, located in the heart of Balboa Park near downtown San Diego, CA. The rehabilitation and seismic retrofit of the 100-year-old structure has already received the 2015 Outstanding Centennial Historic Engineering Project Award from the American Society of Civil Engineers - San Diego and the 2015 Project of the Year Award from the American Public Works Association Chapter for San Diego and Imperial counties.
Working in partnership with the California Department of Transportation (Caltrans) District 11 and Division of Engineering Services, and the City of San Diego, TYLI created a solution to retrofit and rehabilitate the bridge, which was constructed in 1915 for the Panama-California Exposition and is listed on the National Register of Historic Places. The firm was charged with determining the scope and cost of necessary retrofit and rehabilitation work, developing a seismic retrofit strategy, performing a detailed inspection, and preparing final plans, specifications, and estimates for both the rehabilitation and seismic retrofit.
“The T.Y. Lin International team and Caltrans carefully planned the rehabilitation and seismic retrofit construction to ensure that there were no adverse effects to the historic integrity of this important structure,” said Mark Ashley, P.E., TYLI Senior Vice President and West Region Director. “It is also very gratifying to know that this renowned San Diego landmark is now preserved for future generations and safeguarded from loss due to an earthquake.”
The Cabrillo Bridge provides access to Balboa Park for vehicles, bicycles and pedestrians, and links travel to Sixth Avenue, a parallel arterial of SR-163. With over 100,000 vehicles traveling the portion of SR-163 under the bridge each day, the structure is the tourism gateway to Balboa Park, one of San Diego’s main visitor destinations. The Cabrillo Bridge consists of hollow rectangular columns with curved capitals that flare in each direction to form the cantilevered deck. This architectural feature forms the characteristic semi-circular archways that straddle scenic Route 163.
TYLI’s inspection consisted of identifying the locations and extent of unsound concrete and other deficiencies, including non-destructive material testing, concrete coring, and petrographic analysis. A man lift, snooper truck, and scaffolding were utilized to gain access for the inspection. A Pontis software model was used to compare bridge lifecycle costs for rehabilitation versus replacement.
Rehabilitation measures included repairing unsound concrete throughout the structure; restoring the deck drainage system; replacing the internal wood catwalk planks with a new OSHA-compliant catwalk system; installing permanent access features such as doors, ladders, and platforms; new interior lighting, and upgrading electrical components to current code requirements.
TYLI’s seismic retrofit strategy was developed using both response-spectrum and non-linear time history analyses. Retrofit measures included locking the mid-span expansion joints by longitudinal post-tensioning of the superstructure, and strengthening the columns by adding internal post-tensioned shear walls.
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