Soscol Junction

Soscol Junction Project in Southern Napa County

Project to build interchange to relieve congestion at the junction of Route 12/29, Route 121 and Soscol Ferry Road 



Caltrans and the Napa Valley Transportation Authority (NVTA) are currently working together to construct the Soscol Junction Project, a three-year $54 million project to reduce congestion and improve traffic operations in southern Napa County.

At Soscol Junction, State Route 12/29 (a concurrent route hereafter we'll simply call Route 29), State Route 221, and Soscol Ferry Road merge at a signalized intersection. If it weren't enough that three roads meet at one intersection, nearby Devlin Road also funnels traffic onto Soscol Ferry Road not far from the junction. 

To reduce the traffic congestion created by this confluence of routes, Caltrans will build a flyover to connect southbound SR 29 to southbound SR 221 and northbound SR 221 to northbound SR 29.  Beneath the flyover, Caltrans will construct two roundabouts to distribute traffic to the remaining interconnections.  

Napa Valley is one of the most visited destinations in California, with nearly five million visitors annually. As the wineries, resorts and restaurants have proliferated, so has the traffic heading into Napa 

The demand for housing in Napa County lags behind the supply, forcing workers to commute to the Valley. As a result, the rapidly growing Solano County has become a significant source of commuter traffic. Other nearby counties, of course, contribute their share of traffic heading into the valley along with tourist traffic. Freight traffic, once consigned to transporting agricultural products and equipment, has dramatically increase with the rise of the hospitably industry in Napa Valley. 

With such growth in traffic it might have been tempting to construct a large interchange to handle the congestion caused by too many vehicles making too many connections, and such a structure was presented to opinion leaders, local legislators and the public during the early stages of project development. But sentiments strongly opposed a monolithic structure and favored a less obtrusive interchange.  After all, the allure of Napa is many-fold, but the beauty of the area ranks high as a reason to visit, and a sprawling interchange ran counter to the image the populace wanted to project. 

The Soscol Junction Project was designed to move traffic, while keeping a low profile.  Additionally, the interchange supports multi-model traffic, Class -1 pedestrian and bicycle path, as alternative means of travel is another goal of the project.  

The project will also construct 1,200 feet of Class-1 facility to accommodate bicycles/ pedestrians through the intersection.


  • Start Construction:  Summer 2022
  • Open for Traffic: Fall 2024
  • Finish Construction:  Fall 2025

Environmental Report


                    Soscol Junction Present Configuration

Soscol Junction Current Configuration




                   Soscol Junction Rendering of Completed Project 

Soscol Junction Completed Project


























Soscol Junction Draft Public Outreach Video