The Roads Division of Sonoma County Public Infrastructure manages the engineering, construction, and maintenance of bridges on County roads.
The County maintains 323 bridges listed in the National Bridge Inventory (NBI), along with other minor bridges, retaining walls, and transportation structures.
Together, these facilities carry over 800,000 trips per day on average.
Questions about County-maintained bridges may be sent to spi-bridges@sonomacounty.gov.
All NBI-listed bridges in California are inspected by Caltrans Office of Structure Maintenance and Investigations, with additional ongoing County staff inspections. These inspections ensure bridges remain safe and help guide maintenance and repair needs.
The Bridge Crew oversees operations, routine maintenance, and repairs to keep bridges safe and functional. Work ranges from small fixes to larger structural improvements.
Bridge foundations can erode from water flow. County engineers and crews install stabilization measures to protect bridges from scour and ensure long-term stability.
Weather and traffic wear down bridge decks over time. Treatments such as methacrylate sealers or polyester-concrete overlays improve drivability, prevent corrosion, and extend service life.
Many bridges were built before modern earthquake standards. The County identifies vulnerable bridges and upgrades them to better withstand seismic events, protecting the public during major earthquakes.
When a bridge reaches the end of its service life and repairs are no longer effective, the County replaces it with a new, modern bridge designed for today’s safety and traffic needs.
The County maintains 14 bridges designated as Historic Landmarks. Public Infrastructure works with the Landmarks Commission, the State Historic Preservation Officer, and local groups to ensure these historic bridges are properly preserved and treated with care.
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