California Department of Transportation

04/27/2026 | Press release | Distributed by Public on 04/27/2026 16:03

Overnight, Full Highway Closure Of State Route 4 From Tracy Boulevard To San Joaquin/Contra Costa County Line

Overnight, Full Highway Closure Of State Route 4 From Tracy Boulevard To San Joaquin/Contra Costa County Line

Published: Apr 27, 2026

Closure Begins May 2 At 11:00 P.M. Through May 3 At 6:00 A.M. - Detour Required

San Joaquin County - Caltrans will perform an overnight, full highway closure of State Route 4 (SR-4) from Tracy Boulevard to the San Joaquin/Contra Costa County line, east of Discovery Bay, for emergency guardrail repairs at the Middle River Bridge.

This closure will occur beginning at 11:00 p.m. on Saturday, May 2, until 6:00 a.m. on Sunday, May 3, 2026. During this closure the following detour will be required;

State Route 4 Detour Information:

  • Westbound SR-4 travelers: Closure will begin on SR-4 at Tracy Boulevard. From SR-4, travel south on Tracy Boulevard to I-205 west, exit Mountain House Parkway, travel north to Byron Highway to SR-4.
  • Eastbound SR-4 travelers: Closure will begin at Discovery Bay Boulevard. From SR-4, take Byron Highway south to Mountain House Parkway, south to I-205 East, exit Tracy Blvd, north on Tracy Blvd to SR-4.
  • Local access: Only local residents and business owners/employees will have access to locations on SR-4 within the closure limits.

Caltrans will utilize flaggers, as well as overhead and portable changeable message signs, alerting motorists of the detour and potential delays which are expected to be approximately 30 minutes.

Schedules are subject to change due to traffic incidents, weather, availability of equipment and/or materials and construction related issues.

Motorists should expect 5-to-10-minute delays and use alternate routes whenever possible. All work is scheduled to occur as listed but is subject to change due to traffic incidents, weather, availability of equipment/materials, and construction-related issues.

For the safety of workers and other motorists, please Be Work Zone Alert. Caltrans also reminds motorists to #KnowBeforeYouGo by checking QuickMaps on your mobile device or visit quickmap.dot.ca.gov for real-time highway conditions.

California Department of Transportation published this content on April 27, 2026, and is solely responsible for the information contained herein. Distributed via Public Technologies (PUBT), unedited and unaltered, on April 27, 2026 at 22:03 UTC. If you believe the information included in the content is inaccurate or outdated and requires editing or removal, please contact us at [email protected]