State Route (SR) 239 is currently called County Route J4 or the Byron Highway. It’s basically a county road that runs 28 miles from Brentwood past Mountain House into Tracy. Before shopping opportunities arrived in far East County it provided an easy access to the malls in Tracy. Although it has never been constructed it has been designated as a part of the State Highway System since 1957. J4/ Byron Highway carries over 10,000 vehicles per day with over 15% trucks and serves as a major truck route between East Contra Costa County and Tracy and the Central Valley.
Federal legislation enacted in 2005, authorized $14 million in federal appropriations toward construction of the route. Contra Costa County is developing a workplan for the $14million in federal earmarks received for the project. The County requested the funds for planning, environmental clearance and route selection, but the earmark language also specifies “construction”.
The money was granted in two earmarks. The first earmark, $4 million, states that the money should be used to “Conduct study and construct CA State Route 239 from State Route 4 in Brentwood to I-205 in Tracy area”. The initial phase will include the establishment of a multi-jurisdiction steering group to study the route, since the alignment will involve at least two counties (Contra Costa and San Joaquin) and could possibly include Alameda, depending on the route selected. Other task will include an analysis to examine different road classifications, such as regional or county-level expressway and alternate strategies to build, operate and maintain the roadway and finally the ultimate alignment.
The second earmark, $10 million, states that the money should be used to “Construction of and improvements to State Route 239 from State Route 4 in Brentwood to I-205 in Tracy area”. This money will used for preparing the necessary environmental impact documents, the design engineering, right of way acquisition and construction.
The highway will provide a number of benefits:
- Handle growth in truck traffic between the Central Valley and East Contra Costa County
- Improve traffic circulation in southeast Contra Costa
- Relieve some I-580 traffic
- Help long-term economic development in East Contra Costa