The east approach of the Richmond-San Rafael Bridge is just four miles west of the active Hayward Fault and several secondary faults. The San Andreas Fault is about ten miles west of the bridge. In addition to close proximity to the two major fault lines, the consideration of the bridge's survivability in an earthquake due to liquefaction was an important design consideration. Liquefaction is a phenomenon that occurs in the soil as a result of violent shaking during a seismic event. Soft clays and water-saturated geologic sand layers are most susceptible to this phenomenon. During a seismic event, the soft clay and sand turn into slurry, which has almost no ability to support the weight of structures. A majority of the damage that occurred in the bay area during the Loma Prieta quake in 1989 was due to liquefaction. Prior to the Loma Prieta quake, the Hayward Fault was considered to be inactive, because the last major earthquake, attributed to movement along the San Andreas intersection with the Calaveras Fault in 1906, may have relieved stresses built up in crustal rock along local secondary fault lines. Since 1996, the new IBC (International Building Code) and ASSHTO Standard Specifications for Highway Bridges have included stringent requirements for seismic event survivability. Much of the knowledge gained after the 6.9 magnitude Loma Prieta quake and the more recent North Ridge and Kobe quakes is used in evaluating the effect of high-magnitude seismic (6.2 on the Richter Scale) events for the survivability of bridge structures and foundations. This is the design philosophy for upgrading other bridges throughout California, but the retrofit for the Richmond-San Rafael Bridge is the most extensive to date.

Tudor-Saliba/Koch/Tidewater Joint Venture is the prime contractor and D. L. McQuaid is the joint venture's quality control manager. Approximately 75% of the new pile casings have been completed and about 35% of the structural steel subassemblies are in various stages of construction. The pile casings and structural assemblies are fabricated in Vancouver, Wash., St. Louis, Portland, and Salt Lake City.

XKT, Inc., one of the project's steel fabricators, is located at the retired Mare Island Navy Shipyard in Vallejo, Calif., just across the bay. A portion of the structural steel for the steel piers and superstructure sections is fabricated there. The company acquired shop equipment from the U.S. Navy, upgraded it, and installed modern computerized equipment. They have forming rollers that can handle material up to 5-in. thick - Fig. 2. The subassemblies are welded at FCAW-S and SAW stations. Welding procedures and welders are qualified under the supervision of shop CWIs and approved by Caltrans' Materials Evaluation and Testing Service (METS) inspectors. At XKT, bents and tower sections for the steel pier retrofit are assembled and shipped to the project site via barge for installation.

Modern steel fabrication shops at Oregon Iron Works, Thompson Metal Fab, and Universal Structural in Vancouver and Portland are fabricating structural steel subassemblies for shipment to XKT for final fitup. These subassemblies include tower sections (Fig. 3) and pin bases (Fig. 4) along with superstructure retrofit assemblies. Shop CWIs and METS inspectors perform acceptance inspections, and all subassemblies are fitted for bolt-up prior to shipping. Inorganic zinc primer coatings are applied at the Mare Island and Vancouver plants.

Skyline Steel/Profab in St. Louis is manufacturing 66-in. x 3Ž4-in. pile casings using SAW to complete spiral-welded sections. These will be used for CISS (cast in steel shell) piles where reinforced concrete is cast in drilled holes to the specified tip elevation with a socket cut into the bedrock. At the plant, the 66-in. pile sections are inspected to AWS D1.1, Section 6, with UT, meeting the acceptance criteria in Table 6.3.

At the shops, CWI visual inspection and nondestructive examination are used to assure weld quality. Most structural subassemblies are subject to ultrasonic and magnetic particle testing. Some of the more critical beam and column splices are radiographed. The overall weld quality is assessed by METS. Pre-installation inspection is done on site by the joint venture's QC department and accepted by the engineer. Currently, the rejection rate for manufactured assemblies has not exceeded 2%. All repairs are made using either SMAW or FCAW. Any unacceptable SAW pile repairs are done using FCAW or, if necessary, defective welds are cut out. Field welded pile casing repairs are air arc gouged or ground to sound metal, inspected using magnetic particle tests, and then repaired. Field weld rejection rate is less than 1%, based on linear feet of weld.