Napa, CA — The Sonoma County Board of Supervisors approved a $1.8 million allocation on Tuesday to fund engineering and environmental work for the seismic retrofit of the Bohemian Highway Bridge, which spans the Russian River in Monte Rio.
Built in 1934, the bridge has long been considered structurally vulnerable, particularly in the event of a major earthquake. The California Department of Transportation (Caltrans) initially called for the complete replacement of the bridge due to its seismic vulnerability. However, after further evaluation by the Caltrans Office of Earthquake Engineering, the focus shifted to retrofitting the existing structure to address seismic safety concerns without the need for a full replacement.
“This bridge is a critical connection for West County, and I’m glad the seismic upgrade project is finally moving forward after eight years of planning and changes from the state,” said Sonoma County Supervisor Lynda Hopkins. “While we were hoping for a replacement, this project will extend the life of the bridge and address key safety concerns.”
Concerns about the bridge’s structural integrity were first raised by Caltrans in 2012, highlighting issues such as potential seismic vulnerability, deteriorating foundations, and insufficient access for cyclists and pedestrians. At the time, an analysis indicated that replacing the bridge would be more cost-effective than retrofitting the original structure. However, discussions surrounding the retrofit have been ongoing for nearly 20 years.
Efforts to replace the bridge officially began in 2015, with community engagement led by local, state, and federal agencies. Over the course of the project, funding from state and federal grants was secured. A comprehensive Environmental Impact Report (EIR) was completed for the proposed replacement bridge, but the project’s costs and designs continued to evolve. The cost estimate for replacing the bridge rose from approximately $25 million to $88 million, prompting Caltrans to reconsider the best approach. As a result, the focus shifted to a seismic retrofit, which is expected to be more cost-effective while addressing the most urgent safety issues.
The Bohemian Highway Bridge serves as a vital transportation route for the West County community, and local officials and residents have long advocated for its upgrade. Despite the shift away from a full replacement, the seismic retrofit project will ensure that the bridge remains operational for years to come, with enhanced safety measures for both motorists and non-motorized users.