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

October 10, 2019

HEADS UP: Caltrans is scheduled to begin traffic changes to close multiple the offramps and onramps at First Street in the City of Napa effective Thursday, October 10 during construction of three new roundabouts. The First Street offramp from northbound State Route 29 (SR-29) and the First Street loop onramp from eastbound First Street to northbound SR-29 will be closed effective October 10. Also, northbound and southbound California Boulevard will be remain closed between Second Street and Clay Street and no southbound California Blvd. traffic will be allowed to cross First Street. Existing detours will remain in place. These closures are effective Thursday, October 10 through the end of November 2019. Detour signs will be posted.

Additionally, east and west lanes on First Street through the construction area will be shifted to accommodate the next phases of work. Drivers are asked to be aware of the new lane configurations. lanes will be flipped to the newly paved streets so crews can begin work on the other side.

As you can see from the cool photos to the right, a lot of progress has been made on the project. The first of the three roundabouts is beginning to emerge! We are excited to say that the first of the three roundabouts will be open before Thanksgiving, and the second will be open by Christmas! The project contractor, O.C. Jones, took these great photos and has been working diligently to keep this work moving as quickly as possible. We realize the inconvenience this much construction creates, but appreciate our community’s patience as we move closer to finished roundabouts even more quickly than anticipated.

Detours will remain in place, along with previously announced detours currently in place due to the construction. Motorists are encouraged to use alternative routes and allow more time to get to their destinations. Delays are expected in the construction area and drivers should exercise caution.

For more information from Caltrans, visit the Napa Roundabout Webpage at

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: