Map: 

Project Description: 

Caltrans is proposing the Sonoma State Route (SR) 12 Shoulder Widening safety project (Project). The goal of this proposed Project is to improve safety and reduce vehicle collisions. The Project takes place in Sonoma County in the community of Glen Ellen on State Route 12 between Deerfield Ranch Winery near Kenwood and Babb Lane in Glen Ellen (post mile 28.1 to post mile 31.67). The Project proposes widening the existing roadway shoulder on State Route 12 up to 5 feet from the edge of the pavement. This project would add rumble strips on both the outside edge and center of the road to reduce collisions in the Project area. The widening will also include work to manage roadway runoff and maintain effective drainage.

Purpose  
The purpose of the Project is to reduce collisions and enhance safety conditions along SR 12 in Sonoma County. 

Need  
The Project is needed because repeated head-on collisions resulting from centerline crossover incidents have occurred within the Project area. 

Construction Traffic Management 
One-way traffic control with portable traffic lights will be required during construction. No traffic detours or full closures of SR 12 are proposed. Construction would primarily occur during daytime hours, and some may occur at night.  The one-way traffic control would be implemented using traffic cones and temporary railings. These measures will protect the construction work zones, keep travel lanes open as much as possible, and minimize traffic disruption. Caltrans will identify off-peak hours to conduct construction with one-way traffic control and provide continuous access along the highway. 

Proposed Construction Schedule  
Construction will require 160 working days and is anticipated to begin in February 2029. 

What You Should Do: 
Please read this Environmental Document prepared by Caltrans in compliance with the California Environmental Quality Act (CEQA). Click here to download a PDF copy.

We want to hear what you think. If you have any comments about the proposed Project, please submit a comment here.

Please send your comment by the deadline: July 27, 2026. 

You may also send your written comments via postal mail to Caltrans by the deadline to: 
Caltrans District 4, Office of Environmental Analysis 
Attn: Christopher Pincetich 
P.O. Box 23660, MS-8B Oakland, CA 94623-0660.   

Printed copies of the Environmental Document are available for review at: 
•    Sonoma Valley Regional Library at 755 West Napa Street, Sonoma, CA 945476
•    Sonoma County Central Library at 211 E St., Santa Rosa, CA 94504. 

A public information meeting with the project development team is available upon request. If you would like to request an individual meeting to discuss the project or request a public meeting, please contact us at sonoma12_4Q830@publicinput.com

Please send your comment by the deadline: July 27, 2026. 

Funding and Cost: 

This project is funded under State Highway Operation and Protection Program (SHOPP) Safety Improvements. program. The total programmed fund for this project is $14,205,000.