Bay Area Toll Bridges

Carquinez Bridge Seismic Retrofit



BACKGROUND:
The two Carquinez bridges carry approximately 104,000 vehicles per day along I-80 across the Carquinez Strait between Contra Costa and Solano counties. The eastbound Carquinez Bridge was built in 1958 as a part of the route's upgrade to interstate status.  Total bridge width is 52 feet, including four 12-foot lanes and two 2-foot shoulders.  The cantilever steel truss spans total 3,300 feet in length, crossing 140 feet above the twin 1,100-foot wide navigable channels within the Strait.  The eastbound bridge approach and eastbound Crockett Interchange on- and off-ramps are constructed on steel girders and supported by concrete columns/piers of up to 130 feet in height.  Caltrans engineers have determined that seismic strengthening is needed so that the bridge can withstand an earthquake of magnitude 6.5 on the Richter scale on the Franklin Fault with no catastrophic failure or loss of life.

SEISMIC RETROFIT STRATEGY:
Replacing or strengthening steel truss members in the bridge superstructure and towers. Reinforcing pile foundations of Pier No. 5 at the south end of the bridge.
Retrofitting the abutment where the bridge touches down on the northern end.
Strengthening the Crockett Interchange eastbound on- and off-ramps and approach structure.



ENVIRONMENTAL ISSUES:
Categorical Exclusion prepared pursuant to National Environmental Policy Act (NEPA).  The project is statutorily exempt under California Environmental Quality Act (CEQA).  FHWA is the lead agency; the US Coast Guard is a cooperating agency.
Coordination conducted with Bay Conservation and Development Commission (BCDC), US Fish and Wildlife Service (FWS), US Army Corps of Engineers (ACOE). 
Permits were obtained from BCDC, California Department of Fish and Game (CDFG), and  (RWQCB)


US COAST GUARD ISSUES:
The USCG approved the project as "repair-in-kind".  Most of the retrofit work will occur within the Carquinez Strait navigation channels, there was close coordination with the Eleventh Coast Guard District in Alameda, California.  A Coast Guard checklist, consisting of navigational and marine safety issues, was developed specifically for this retrofit project.  Contractors working on the Bridge will adhere to the safety checklist.  Restrictions on the contractors operation will be required to minimize any hazards to navigation.


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