Interchange upgrades crucial for Central County traffic

It’s official: The first segment of the Interstate 680/State Route 4 Interchange Improvement Project broke ground.
In addition to being the District 4 supervisor, I am a commissioner for the Contra Costa Transportation Authority (CCTA). One of my highest priorities is to ensure that residents of our county get from point A to point B safely and smoothly with minimal traffic.

Anyone who has driven during commute traffic hours can testify to the need for improvements to the 680/4 interchange. I-680 is the main artery that connects central Contra Costa County to Solano, Alameda and Santa Clara counties, while SR4 serves as the only major link to connect East Contra Costa County with other parts of the county.

Since there are several improvements needed, this project has been broken into segments. The first segment will widen four miles of 4 from Morello Avenue to State Route 242 by adding a third lane in both directions. This additional lane will allow for a safer lane transition while merging from the cloverleaf of 680 to 4.

The project will also raise the profile of the roadway and widen the median and the outside shoulders at Grayson Creek. This phase will lay the foundation for future segments, which include improvements to the connector ramps to 4 and 680. Not only will the widening increase capacity, but small upgrades like lighting and new lane striping will improve road visibility at night and increase safety overall.

This project is possible because of Senate Bill 1, which created a new funding source from the state for cities and counties to use for road maintenance.

The 680/4 interchange project is a partnership between CCTA and the California Department of Transportation (Caltrans). CCTA was formed to manage the county’s transportation sales tax program and oversee countywide transportation planning efforts and projects. CCTA is also the Congestion Management Agency, responsible for programs to keep traffic levels manageable. Caltrans manages California’s highway and freeway lanes.

The construction of the first segment of this project is expected to be completed in late 2021, for a cost of $136 million.

Karen Mitchoff is Contra Costa County District IV supervisor. Email questions or comments to

Karen Mitchoff