Caltrans To Begin State Route 4 Delta Pavement Improvement Project From Old River Bridge To South Whiskey Slough Road

One-Way Traffic Control Begins March 15, 2026, Through January 2027 - Two Full Highway Closures Required - (Dates To Be Announced)

San Joaquin County- Caltrans will soon begin the State Route 4 (SR-4) Delta Pavement Improvement Project that will make necessary upgrades and repairs of approximately nine miles of existing highway between the Old River Bridge, located at the San Joaquin/Contra Costa County line, east of Discovery Bay, and South Whiskey Slough Road in Holt, just west of Stockton.

This $21.6 million project will be performed by Bay Cities Paving & Grinding, Inc. (Concord, CA) and is scheduled for 185 working days beginning the week of March 15-21, with completion expected in February 2027 (weather permitting).

The purpose of this project is to preserve and extend the life of the existing pavement, while improving ride quality for motorists as the pavement within the project limits is exhibiting major distress, which if left uncorrected would continue to deteriorate.

Work will include the repair of failed areas of pavement (dig outs), followed by cold plane and overlay of the existing pavement. Shoulder backing will be placed in both directions, along with upgrading departure barriers, electrical elements, traffic management systems, lighting systems, and sign panels.

Required Highway And Bridge Closures:

• Overnight, one-way traffic control to be performed at various eastbound and westbound locations on SR-4 on Sundays-Thursdays, through February 2027.
• Two, 55-hour/weekend, full highway closures of SR-4 will take place from 10:00 p.m. on Fridays, through 5:00 a.m. on Mondays. Specific closure dates to be announced once finalized and will require the following detour:

• State Route 4 Detour Information:

  • Westbound SR-4 travelers: The detour begins at the Tracy Boulevard intersection; south on Tracy Blvd; west on I-205; north on Mountain House Parkway; northwest on Byron Road to SR-4.
  • Eastbound SR-4 travelers: The detour begins at the Byron Road intersection; southeast on Byron Road; south on Mountain House Parkway; east on I-205; north on Tracy Blvd to SR-4.

Caltrans will utilize roadside and portable changeable message signs alerting motorists of the lane closures and potential delays, which are expected to be approximately 30 minutes. For more information on this project, please visit: https://dot.ca.gov/caltrans-near-me/district-10/district-10-current-projects/10-1f320.

Caltrans is aware of the impact on motorists during construction of this project, as well as the Old River Bridge Additional Maintenance project, which are both occurring concurrently on SR-4. Originally, the Old River Bridge project was scheduled to begin in late 2024, however, it was delayed as it had to be re-packaged and re-advertised before becoming fully funded in August 2025.

Caltrans would like to thank motorists for their patience during construction of these significant projects.

All work is scheduled to begin as listed, but is subject to change due to traffic incidents, weather, availability of equipment, and/or materials and construction related issues. For the safety of workers and other motorists, please Be Work Zone Alert.

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. For the latest highway conditions, visit quickmap.dot.ca.gov