I-580 & International Pkwy/Patterson Pass Rd Interchange Project

Project Overview

The City of Tracy, in cooperation with the California Department of Transportation (Caltrans), is proposing to modify the existing compact diamond (Type L-1) interchange at Interstate 580 (I-580) and International Parkway/Patterson Pass Road to a diverging diamond interchange (DDI).

This project is necessary to accommodate the increased traffic demand resulting from the Cordes Ranch Specific Plan development and surrounding areas in Tracy. The Cordes Ranch Specific Plan Environmental Impact Report identified that traffic from the development would significantly impact the I-580 interchange intersections. This project implements the required mitigation measures to reduce those impacts while improving local traffic circulation and discouraging highway traffic from using local roadways.

What is a Diverging Diamond Interchange?

A diverging diamond interchange (DDI) is an innovative design that improves traffic flow and safety. In a DDI, traffic on the crossroad briefly shifts to the left side of the road, allowing vehicles to move through the interchange more efficiently.

Key features of the DDI design include:

• Reduced conflict points between vehicles, improving safety
• Elimination of left-turn signal phases, reducing wait times
• Improved traffic flow for freeway on-ramps and off-ramps
• Better accommodation of heavy traffic volumes
• Proven success in similar locations across the country

Project Benefits

• Reduce congestion at the I-580 and International Parkway interchange
• Improve traffic flow and reduce wait times at the intersection
• Enhance safety for motorists through reduced conflict points
• Support planned economic development in the Cordes Ranch Specific Plan area
• Improve local traffic circulation throughout Tracy
• Accommodate future traffic growth in San Joaquin County
• Discourage highway traffic from using local roadways

Project Schedule

March 2021: The project was exempted by CEQA and cleared with a NEPA Categorical Exclusion (CE) determination.

Project Updates April 2026

I-580 & INTERNATIONAL PKWY/PATTERSON PASS RD INTERCHANGE

Lane Closure Update – Week of April 26, 2026

Nightly lane and ramp closures are scheduled Sunday, April 26, through Thursday, April 30, at the Patterson Pass Road overcrossing on I-580.

Eastbound I-580 (nightly, approx. 9:01 PM – 5:59 AM):

• 1 of 2 mainline lanes closed

• EB off-ramp at Patterson Pass Rd closed

• EB on-ramp at Patterson Pass Rd closed

Westbound I-580 (nightly, approx. 9:01 PM – 3:30 AM):

• 1 of 2 mainline lanes closed

• WB off-ramp at Patterson Pass Rd closed

• WB on-ramp at Patterson Pass Rd closed

Closures are weather-dependent and subject to change. Check Caltrans QuickMap for real-time conditions at quickmap.dot.ca.gov.

Questions or concerns?
Project Phone: (209) 208-0735
Project Email: tracy580ddiproject@gmail.com

Project Funding

Estimated Project Cost: $61,903,749 million

The project will be funded through a combination of federal, local and regional sources:

• Federal Trade Corridor Enhancement Program (TCEP)
• City of Tracy Transportation Impact Mitigation Fee
• City of Tracy Regional Transportation Impact Fee
• San Joaquin Council of Governments (SJCOG) Measure K

Schedule

The City of Tracy is committed to minimizing impacts during construction. The project team will work to:

• Maintain access to local businesses throughout construction
• Provide advance notice of traffic changes and detours
• Coordinate construction activities to minimize disruption
• Keep the public informed through regular updates
• Maintain at least one lane of traffic in each direction during peak hours

STAY INFORMED

We want to hear from you! If you have any questions or concerns about the I-580 Diverging Diamond Interchange project, please don't hesitate to reach out to us.

Project hotline: (209) 208-0735

Project email: tracy580ddiproject@gmail.com