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.

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Page 31 of 55

Steel Fins 14'-0" Typ 3 Equal spaces 4'-0" 4'-0" 15" Typ 1'-6" Typ 12'-9" 10" 11'-0" The existing south access road to the iconic Golden Gate Bridge, known as Doyle Drive, is structurally and seismically deficient and needed to be replaced. The roadway is facing the same problem that threatens other parts of our nation's infrastructure— the ravages of time and heavy use. Originally built in 1936, Doyle Drive has reached the end of its useful life. The Presidio Parkway project, the Doyle Drive replacement, will result in a dramatic visual and structural change for the corridor. The $1.045 billion project is divided into two phases. The first phase, currently underway, involves construction of one of two new viaducts, one of four cut- and-cover tunnels, and an at-grade temporary bypass at the eastern end of the project. The new Presidio Viaduct currently under construction is one of the landmark structures of this extensive project. Several bridge types were considered during the design phase, including parabolic, prestressed concrete box girders, steel tubular trusses, and Warren steel trusses with composite concrete deck and soffit. The selected bridge is a six-span, cast- in-place, prestressed concrete box girder with three main spans of 275 ft (Spans 2, 3, and 4). Spans 1, 5, and 6 have lengths of 188 ft, 184 ft, and 143 ft respectively, resulting in a total bridge length of 1340 ft. The bridge has a uniform superstructure depth along its length, with the depth varying transversely. The depth is 12.75 ft at the middle of the cross section, but curves upward to a depth of 11 ft at the face of the exterior webs. The superstructure cross section includes a 14-ft deck overhang on each side with architectural steel fins spaced at equal intervals along profile PRESIDIO VIADUCT / SAN FRANCISCO, CALIFORNIA bRIDge eNgINeeR: California Department of Transportation, Sacramento, Calif. pRIme CoNTRACToR: CC Meyers Inc., Rancho Cordova, Calif. CoNCReTe SupplIeR: CEMEX, San Ramon, Calif. poST-TeNSIoNINg SupplIeR: Schwager-Davis Inc., San Jose, Calif. ReINFoRCemeNT SupplIeR: Harris Salinas Rebar Inc., Livermore, Calif. by Ahmed M. M. Ibrahim, John F. Walters, and Ofelia P. Alcantara, California Department of Transportation (Caltrans) Presidio Viaduct Rendering of the Presidio Viaduct. All photos, drawings, and rendering: Caltrans. South Access to the Golden Gate Bridge Typical cross section of Frame 1. 30 | ASPIRE , Winter 2012 Book_Win12.indb 30 12/29/11 11:12 AM

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