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/306885
14 | ASPIRE , Summer 2008 P E R S P E C T I V E the widened structures had to match the structural seismic and gravity response characteristics of the existing cast-in-place box girder bridges that are both continuous longitudinally and monolithic with the substructure. And finally, disruptions to traffic had to be minimal during construction. As with many states, California is faced with diminishing open space to improve congested transportation networks. Therefore, most of these improvements involve heavily-congested urban interchanges, where traffic disruption is not acceptable. Efforts are further hampered with construction cost increases in recent years that have largely outpaced inflation; thus delays in project delivery effectively diminish available budgets. All of this underscores the importance of delivering sustainable concrete bridges both cost-effectively and in an accelerated schedule. Bridge construction is often in the critical path of larger transportation improvement projects and is a significant portion of the overall project cost. When owner agencies and industry c o l l a b o r a t e , t h e c o s t b e n e f i t s o f sustainable concrete bridge delivery are maximized, as demonstrated by the recently completed widening of the State Route 22 freeway in Southern California. Twenty-two bridges were widened, nine bridges were replaced, and three new bridges were added in an aggressive design-build schedule. These bridge improvements were part of an overall project to eliminate bottlenecks, reduce congestion, and improve safety on a 12-mile stretch of Route 22, located in Orange County, California, extending from Valley View Boulevard to its terminus at State Route 55. This project added a high-occupancy vehicle (HOV) lane, auxiliary lanes, shoulders along with ramp replacement, and interchange reconfiguration. The $670 million project was funded by the Orange County Transportation Authority (OCTA), and delivered using design-build, led by the Granite-Myers- Rados (GMR) joint venture. The GMR team hired PBS&J as the lead structural engineer in design and construction support. A collaborative environment facilitated by innovative project delivery methods was crucial in not only meeting the aggressive design-build schedule but also maximizing economy. A significant challenge on the project was maintaining acceptable vertical clearance of the undercrossing and separation widening because widened bridge structures had to match the existing cross-slope and profile. Further, by Jay Holombo, Vinh Trinh, and Maher K. Tadros, PBS&J SuStainable Concrete bridge Design Formwork is placed around precast girders in the construction of a seismic- resistant integral connection with the columns. Photo: Jay Holombo, PBS&J. Completed low-profile precast concrete girder undercrossing on SR 22. Photo: Vinh Trinh, PBS&J. Aspire_sum08.indb 14 6/24/08 1:24:51 PM