Interstate 5 Louise Avenue Interchange Improvement

Project Description

This project consists of the design and construction of the Interstate 5 / Louise Ave interchange ultimate improvements. Staff is currently pursuing a Diverging Diamond Interchange (DDI) layout with Caltrans. The DDI will accommodate traffic needs while reducing construction costs and right of way acquisitions. The project phases include Project Approval and Environmental Document (PA&ED), right of way acquisition, Plans, Specifications and Estimate (PS&E) and construction.  Due to the large construction cost associated with the ultimate interchange improvements and the need for immediate enhancements in traffic operations, City staff has worked with Caltrans to stage the construction.


Project Benefits


The purpose of the proposed project is to reduce congestion, improve traffic operations and accommodate anticipated travel demand due to development approved by the City of Lathrop General Plan. Significant economic growth is projected west of the Interstate 5/Louise A venue/River Islands Parkway interchange. Anticipated traffic volumes far exceed current capacities of the existing interchange due to the area's new development. The Louise Avenue/River Islands Parkway Interchange is an important link to I-5 for the City of Lathrop and the surrounding community. The proposed improvements to the interchange will allow the City to continue with the planned growth. The interchange improvements will also improve traffic operations for commuters traveling into and out of Lathrop. These improvements will enhance the traffic operations for through traffic on I-5 by providing improved on and off-ramps at the interchange. The projected growth in and around Lathrop will put traffic demands on the interchange that can not be met unless improvements are made to the existing interchange. Specifically, the project purpose is to:

  • Improve local east-west circulation in Lathrop between State Route 99 and Interstate 5
  • Improve access to Interstate 5
  • Improve traffic operations at the interchange
  • Improve traffic operations on Interstate 5



The project improvements are needed because Lathrop is projected to face increased traffic demands at the Interstate 5/Louise Avenue/River Islands Parkway Interchange, the increased traffic demands will be the result of planned growth in the area. Traffic will experience delays and extensive queuing due to congestion without these improvements. This, in turn, will bring about inefficient fuel consumption, deteriorating air quality, and unacceptable level of service conditions. Without the proposed interchange improvements, these problems would significantly degrade the operations of the Interstate 5 freeway system.


Funding Source

Locally Funded


Project Cost/Programmed

 Programed Project Cost Capital $ Support $
Project Approval & Environmental Document $0 $400,000
Plans, Specifications, & Estimates $0 $0
Right of Way $0 $0
Construction $0 $0


Projected Cost as of (December 2022) Planned $ Expended $
Project Approval & Environmental Document $0 $380,000
Plans, Specifications, & Estimates $0 $0
Right of Way Support $0 $0
Construction Support $0 $0


Current Schedule

 Process Date
Project Study Report (M010) To Be Determined
Project Approval & Environmental Document (M200) November 2023
Right of Way Certification (M410) To Be Determined
Ready to List (M460) To Be Determined
Approved Construction Contract (M500) To Be Determined
Project Completion (M600) To Be Determined


Project Status

The project is currently in Project Approval & Environmental Document (PA&ED) phase.


Project Contact

Caltrans District 10 - Public Information Office
Phone: (209) 948-7977


Title VI Information

The California Department of Transportation (Caltrans) assures that no person shall, on the basis of race, color, or national origin, be excluded from participation in, be denied the benefits of, or be otherwise subjected to discrimination under any program or activity receiving Federal financial assistance, as required by Title VI of the Civil Rights Act of 1964, as amended, the Civil Rights Restoration Act of 1987, and Federal Executive Order 12898 (Federal Actions to Address Environmental Justice in Minority Populations and Low-Income Populations).

Caltrans will make every effort to ensure nondiscrimination in all of its programs and activities, whether they are federally funded or not, and that services and benefits are fairly distributed to all people, regardless of race, color, or national origin. In addition, Caltrans will facilitate meaningful participation in the transportation planning process in a nondiscriminatory manner.