Bridges

Bridges on the Sonoma County road system are maintained by the Roads Division of the Sonoma County Department of Public Infrastructure. Public Infrastructure currently maintains 323 bridges listed in the National Bridge Inventory (NBI) in addition to other minior bridges, retaining walls and other transportation structures, which serve over 800,000 trips per day on average.

Inquiries related to bridges maintained by Public Infrastructure can be sent to spi-bridges@sonoma-county.org. 

Load rating and other information about bridges maintained by the County of Sonoma can be found on our Interactive Map. Other NBI Bridge data can be found here.

Bridge Inspections

In California, all NBI-listed bridge structures in California are inspected by the California Department of Transportation Office of Structure Maintenance and Investigations. A bridge inspection examines the structural health of each bridge and makes recommendations for repairs and maintenance. State inspections are coupled with ongoing staff inspections to form the basis for the County's Bridge Program.

Maintenance and Repairs

The Bridge Group of Public Infrastructure oversees a variety of work related to the operations, maintenance, repair, and improvement of bridges and transportation structures.

Bridge Scour Protection

Erosion around bridge foundations poses a risk to the health and structural stability of the bridges. Public Infrastructure engineers and maintenance crews implement stabilization measures to protect and stabilize County bridges from scour.

Resurfacing

Weathering causes cracking and spauling of the deck surface over time. If untreated the damage can allow corrosion of bridge steel and risk harm to the strength of the structure, as well as reduce riding comfort for drivers. Public Infrastructure engineers and maintenance crews implement treatments, such as methacrylate sealer or polyester-concrete overlays to improve drivability and protect structural health.

Seismic retrofits

The engineering profession has improved the understanding of the effects of earthquakes on bridges since many of the bridges in the County were built. Public Infrastructure identifies vulnerable bridges and implements modifications or enhancements to bridges which protect the public during a major seismic event.

Reconstruction

When a bridge reaches the end of its service life and cannot be maintained in a serviceable condition, Public Infrastructure will implement projects to remove deficient bridge and construct modern bridges to serve in its place.

Landmark and Historic Bridges

Public Infrastructure maintains 14 bridges which are designated as Historic Landmarks by the Sonoma County Landmarks Commission. The Bridge section works with the Landmarks Commission, the State Historic Preservation Officer, and location historic groups to ensure the proper treatment of these historic properties.