State Route 239 Project
The State Route 239 project will provide a new, four-lane highway from State Route 4 at Marsh Creek Road in Contra Costa County to Interstate 580 in Alameda County. This new state route will ultimately improve the transportation network for an area that had few viable north-south roadway connections between East Contra Costa and the Central Valley.
This project is being led by the Contra Costa Transportation Authority (CCTA) in partnership with Contra Costa County and Caltrans.
The State Route 239 project is particularly important now, to provide relief from increasing commute traffic through the town of Byron, enhance mobility in East Contra Costa, and improve access to the Byron Airport.