Soscol Junction Improvement Project Breaks Ground in Napa

Project will replace outdated intersection with an overpass and two roundabouts

Caltrans and the Napa Valley Transportation Authority broke ground today on the Soscol Junction Interchange Project in southern Napa County. The $54 million project includes nearly $24 million in funding from Senate Bill (SB) 1, the Road Repair and Accountability Act of 2017.

The three-year project will replace the signalized intersection of State Route 12/29, State Route 221 and Soscol Ferry Road with an interchange composed of an overpass and two roundabouts, a configuration that will add fluidity to traffic flow, reduce congestion and enhance bicycle and pedestrian connectivity.  

“Working with the Napa Valley Transportation Authority, we created a plan to construct an interchange that significantly reduces traffic congestion yet blends with the surrounding landscape,” said Caltrans District 4 Director Dina El-Tawansy. “Better still, the interchange includes bicycle and pedestrian lanes that will eventually connect with the Napa Vine Trail.”

Unlike a typical interchange with an elevated overpass where motorists make inter-route connections, most motorists at Soscol Junction will make connections at surface level on roundabouts. Napa, which is a tourist destination, desired a low profile interchange. Caltrans crews will landscape the area with local plants, including oaks whose canopies will visually screen the interchange from distant onlookers.

In addition to the SB 1 funding, the project will be paid for with $29.8 million in state and regional funds and $3.7 million in local funds. 

“The Soscol Junction Project will dramatically improve the gateway to downtown Napa, and other parts of this remarkable Valley," said Liz Alessio, Vice Chair of the Napa Valley Transportation Authority, “bringing workers to jobs, and visitors to our wineries and hotels and shopping centers like South Napa Marketplace and Oxbow, students to our campuses and residents to new affordable housing developments along the Soscol Corridor, and the Napa Pipe community development.”

Caltrans will build 1,200 feet of Class I bicycle and pedestrian paths as part of the project. Eventually the bicycle/pedestrian lanes will connect to the Vine Trail, a 47-mile multi-use path that will stretch from Calistoga to the ferry in Vallejo. 

Ghilotti Construction is the contractor for the project.

For more information visit the Soscol Junction Project webpage:

SB 1 provides $5 billion in transportation funding annually split between the state and local agencies. Road projects progress through construction phases more quickly based on the availability of SB 1 funds, including projects that are partially funded by SB 1. For more information about other transportation projects funded by SB 1, visit