Update: Overnight Full Closures of State Route 4 (Marsh Creek Road) Between Vasco Road and Byron Highway in Contra Costa County

Sunday, May 3,2026 to Thursday, May 21, 2026: nightly closures from 8:00 PM to 5:00 AM (Sunday through Thursday). Note: May 3rd closure is from 7:30 PM to 5:00 AM.

Contra Costa County - Caltrans construction will soon start a paving project on State Route 4 (SR-4), between Hillcrest Avenue and Byron Highway in Contra Costa County. For the safety of both workers and motoring public, full closures of SR-4 Marsh Creek Road between Vasco Road and Byron Highway will be in effect. Closures begin at 7:30 PM on Sunday, May 3, 2026, and last until 5:00 AM; they will continue nightly through Thursday, May 21, 2026, each Sunday through Thursday from 8:00 PM to 5:00 AM. Access during these times will only be available to local residents as well as business owners and employees needing to reach locations within the closed section of SR-4.

Please note all work is weather dependent and subject to change.

State Route 4 Marsh Creek Road Detour Information:

• Westbound SR-4 Travelers: Detour begins at Byron Highway left on Brentwood Blvd., left on Balfour Rd., right on to westbound SR-4.

• Eastbound SR-4 Travelers: Detour begins at Vasco Road; left on Walnut Blvd, right on Payne Ave, left on Sellers Ave, right on Brentwood Blvd, continue on Byron Hwy to eastbound SR-4.

Please follow posted signs and detour routes during these closure periods.Motorists are advised to expect delays and allow extra time.

For 24/7 traffic updates, please visit 511.org: https://x.com/511SFBay
For real-time information, visit Caltrans QuickMap: https://quickmap.dot.ca.gov
Follow us on X: https://x.com/CaltransD4
Or call 1-800-472-7623, 1-800-427-ROAD for state highway conditions statewide.