King Ridge Road Bridge Replacement over Austin Creek

Location: 21653 King Ridge Rd (Lat/Lon: 38.561, -123.102)

Sonoma County is currently working towards replacing the single-lane bridge over Austin Creek, on King Ridge Road. The bridge requires replacement due to scour deficiencies and seismic deficiencies.

The proposed new bridge will be a single span (no piers in the stream), steel girder bridge, consisting of two 11 ft lanes and 3 ft shoulders. The new bridge will be constructed upstream (east) of the existing bridge on a new alignment. The existing bridge will remain open to traffic during construction and will be removed after the new bridge is opened to traffic. The substructure shall consist of seat type abutments on footings with Cast-in-Drilled-Hole (CIDH) piles to minimize construction noise. Construction is anticipated to be performed over a single season. The project is currently in the environmental process with various studies ongoing. Planned National Environmental Protection Act (NEPA) clearance date is spring 2022.

Project Goals:
• Replace existing bridge with a bridge that meets modern design and construction standards
• Design a bridge that reflects local character and environment
• Improve safety and access for drivers, pedestrians, cyclists, and emergency services

Project Status:
The project is currently in the National Environmental Protection Act (NEPA) environmental process, with various technical studies ongoing. Anticipated NEPA clearance date is fall 2022.

Estimated Target Dates (subject to change):
• NEPA Clearance fall 2022
• CEQA Clearance fall 2023
• Permitting 2024
• Right of Way acquisition 2024
• Construction 2025

Please direct any questions to Chet Jamgochian at chet.jamgochian@sonoma-county.org.