State Route 29/California Roundabouts

Project Description/Background

The State Route 29 (SR 29) Northbound First Street Ramps and California Boulevard Roundabouts Project (Project) involves the reconfiguration and construction of three modern roundabouts at First Street and California Boulevard, Second Street and California Boulevard, and SR 29 northbound on and off ramps at First Street.

The purpose of the Project is to relieve existing and future traffic congestion, improve traffic safety and traffic operations, and minimize queues and delay for all three intersections within the Project limits.  Furthermore, the Project includes bicycle and pedestrian facilities to encourage multi-modal forms of transportation.

The Project will accommodate bicycle and pedestrian traffic through a combination of sidewalks, shared use paths and bicycle lanes. Other features of the project include street lighting, landscaping, irrigation and storm drain systems, new side mounted and overhead signs to assist in navigating the roundabouts, the construction of retaining walls, and re-grading to accommodate street design grades and cross-slopes.

The Project will also increase mobility into and out of Downtown Napa through the reversal of First Street and Second Street between California Boulevard and Jefferson Street. Currently, First and Second Streets, between California Boulevard and Jefferson Street operate as a one-way couplet (with east and west-bound traffic separated onto two two-lane streets, rather than allowing two-way traffic on both streets). As part of the Project these streets will be reversed: First Street would become east-bound only, while Second Street would become west bound only, each from the California Boulevard roundabouts to Jefferson Street.

CA Roundabouts Concept

Construction Activities


AT&T and Comcast utilities have been relocated. Pre-project tree removal. 

Coming Up: 

Caltrans has closed the northbound First Street onramp to northbound State Route 29 (SR-29) in downtown Napa this week, which will last approximately through August 30 of this year to accommodate construction at the northwest corner of the intersection of First Street and California Boulevard in Napa.

A detour will be in place to help motorists on northbound First Street to get onto the onramp to northbound SR-29. Detour signs will be in place to guide traffic to the detour (see map).

Also, southbound California Boulevard at Second Street will be reduced from two lanes to one lane to accommodate construction at the northwest corner of California Boulevard and Second Street. This lane reduction will begin at 8:00 AM Wednesday, June 19, and will be in place up until early fall of this year.

The purpose of the ramp closure and the lane reduction is to accommodate construction on one of the three roundabouts that will be installed in the project. Work on the three roundabouts is expected to conclude in 2020.

Project Simulation

The design consultant for the Project, Omni-Means (A GHD Company), prepared a traffic simulation to illustrate how the Project will operate after completion.


Comments and questions may be directed to the Engineering Division email address: