ASPIRE is a quarterly magazine published by PCI in cooperation with the associations of the National Concrete Bridge Council. The editorial content focuses on the latest technology and key issues in the Concrete Bridge Industry.
Issue link: http://www.aspiremagazinebyengineers.com/i/306183
An Iconic Bridge for One of America's Finest Cities For an engineer, a pedestrian bridge is like a child's blank canvas, allowing nearly unlimited creativity in structural f o r m . T h e re s i m p l y a re n o t t h e restrictions with geometry, structural systems, and details that constrain the engineer on a conventional vehicular bridge design. Winding ramps and stairs, inclined members, challenging cable geometry; are all possible on a pedestrian bridge. With far more freedom than with a vehicular bridge, the pedestrian bridge allows for greater expression. There are less geometric constraints. Cars just don't like highly curved superstructures, but people do. In addition, the practical monetary constraints on a vehicular bridge can be greatly reduced on a pedestrian bridge. Their smaller scale makes them inherently less costly, even though their unit cost is much higher. Therefore, a community may be able to spend several million dollars more for a unique pedestrian bridge, while this same amount spent on a vehicular bridge would certainly enhance it, but may not be enough to allow for an iconic structure. Fine detail can be incorporated into the design and appreciated by pedestrians, whereas, on a vehicular bridge, a motorist traveling at highway speed cannot possibly see or appreciate such detail. With these f re e d o m s , a n d t h e b e a u t i f u l S a n Diego, Calif., downtown landscape as the canvas, we were able to create a dynamic, dramatic, and iconic structure. The City of San Diego downtown area is situated on the San Diego Bay. For many years, it has been the goal of the city to complete a pedestrian and bicycle link between the historic Balboa Park and the picturesque San Diego Bay, dubbed the Park-to-Bay Link. The last section of the Link was blocked by local trolley tracks, several sets of freight train tracks, and a busy downtown thoroughfare. In 2004, the city commissioned the Centre City Development Corporation (CCDC), the city's redevelopment agency, to design and build a bridge to complete the approximately 2-mile-long Park-to- Bay Link. The site chosen for the final bridge link is adjacent to the recently constructed Petco Park, home of Major League Baseball's San Diego Padres and the San Diego Convention Center on the San Diego Bay, covering over 1 million ft 2 . high-profile Solution CCDC recognized that the high-profile project location needed a landmark structure to act as the gateway to the city and as an icon of the revitalized downtown area of San Diego. They hired the design team to develop a concept and plans for the bridge and surrounding plazas. Although many alternatives were considered for the site, the final bridge type selection was a self-anchored suspension bridge with an inclined pylon. The horizontally-curved superstructure of the 355-ft-long main span is a 3-ft-deep, single-cell, hollow, box girder section. The full 19-ft 7-in.- section width includes a 9-ft 1-in.-wide profile HARBOR DRIVE PEDESTRIAN BRIDGE/ SAN DIEGO, CALIFORNIA CLIE nT: Centre City Development Corporation, San Diego, Calif. BRIDgE DESIgn EngInEER: T. y. Lin International, San Diego, Calif. ARC hITECT: Safdie Rabines Architects, San Diego, Calif. COnCEpT COLLABORATIOn AnD InDEpEnDEnT ChECK: Strasky and Anatech, San Diego, Calif. pRIME COnTRACTOR: Reyes Corporation, National City, Calif. COnCRETE SUppLIER: Hanson, San Diego, Calif. Te Harbor Drive Pedestrian Bridge The bridge carries pedestrians over a series of railroad lines including heavy freight, passenger rail, and trolley lines. It also allows pedestrians to cross over a busy downtown street and connects directly with a multi-level parking structure. Photo: Paul Savage. All other photos and drawings: T.Y. Lin International. by Joe Tognoli and Dan Fitzwilliam, T. Y. Lin International 26 | ASPIRE , Spring 2011 Book_Spr11.indb 26 3/30/11 5:09 PM