DISCOVERY BAY NEWS | EAST CONTRA COSTA AND SAN JOAQUIN COUNTY DELTA | October 18, 2026. Travelers using the rural western portion of State Route 4 through the Delta should plan around a 36-hour full highway closure scheduled for next weekend. According to Caltrans District 10, the restriction will extend between Roberts Road and Old River Bridge, from 10 p.m. Friday, October 23, until 10 a.m. Sunday, October 25, 2026.
This is a scheduled construction closure, not confirmation that the highway is closed on October 18. Exact barricade placement, available alternatives and the schedule may change; drivers must obey posted traffic control and use official updates.
Where is the closure?
The Old River Bridge lies at the San Joaquin–Contra Costa county line. The affected SR-4 segment crosses the Delta landscape used by commuters, agricultural businesses, residents and visitors. Although this report is presented by Discovery Bay News because of its regional travel importance, the specified construction segment is not inside the central Discovery Bay community. That distinction matters when planning a route.
The project notice also references previous nighttime one-way traffic control between Whiskey Slough and Old River Bridge during October 11–16. The older night-control window should not be confused with the upcoming full closure of the Roberts Road–Old River Bridge section.
Why the road is closing
Caltrans says the restrictions are part of the SR-4 Delta Pavement Improvement Project. That work involves repairing roadway pavement and associated improvements. The stated 36 hours is the planned uninterrupted full-closure period for this stage, not the expected total duration of the entire pavement project.
How to plan a trip without a dangerous shortcut
- Check Caltrans QuickMap before departing, including the road-closure layer.
- Use an official detour or well-established state or county road connection suited to your vehicle. Avoid relying on an unverified navigation shortcut over privately maintained levee roads.
- Allow time for trucks, farm traffic and service vehicles whose alternative routes may differ from passenger cars.
- For emergency access, follow instructions from local law enforcement and public-safety officials rather than a generic online map.
Caltrans’ October 9 release does not provide a minute-by-minute travel time or a detailed signed-detour map in the text. California58 therefore does not invent a specific detour. Construction and weather conditions can alter the posted hours.
What changes for residents?
The temporary loss of the Roberts Road–Old River Bridge route may require long deviations around Delta waterways. Drivers should verify the opening status before attempting this segment on Saturday, October 24, and early Sunday, October 25. For more detail, read the official traffic advisory and the project overview.
Editorial note: October 9 Caltrans release, reviewed October 18. Dates reflect the agency’s announced plan; no live road status, alternate route or geographic boundaries beyond the agency’s description are invented.
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