I-405 Improvement Project (SR-73 to I-605)

Easing Gridlock Along the San Diego Freeway

About 430,000 vehicles travel the San Diego Freeway (I-405) every day. By 2030, the volume is expected to increase by nearly 23 percent—threatening to worsen gridlock and commuter delays.

As part of efforts to increase freeway capacity and improve congestion along I-405, the Orange County Transportation Authority (OCTA) and Caltrans embarked on a $1.217 Billion project that added new lanes, updated interchanges, and integrated merging lanes near on- and off-ramps.

A subconsultant on the project, Harris & Associates was responsible for a variety of vital tasks, including: completing quality verification on roadway activities in accordance with contract requirements; coordinating field activities with the design-builder and quality verification inspectors; public relations; and traffic control.

Core Elements

The scope of the project, completed in 2023, includes the 16 miles of I-405 between the SR-73 freeway in Costa Mesa to the south and I-605 near the L.A. County line to the north. Improvements include new bike lanes and sidewalks, new regular and Express Lanes, several interchange reconfigurations, and over 18 new, replaced, and widened bridges.  

Harris worked closely with partners on the design-build project to:

  • Coordinate among the design-builder’s quality control and quality assurance staff for activity inspection and acceptance
  • Coordinate traffic control using Caltrans’ Lane Closure System
  • Schedule California Highway Patrol for traffic closure support
  • Review and approve monthly progress payment requests
  • Support the program manager with ongoing activities
  • Support the stormwater pollution prevention plan, the maintenance inspection, and task order log
  • Support environmental and permit compliance activities

A combination of local, state, and federal funds support the project, while Express Lane tolls will cover Express Lane improvements.

Beyond the Blueprints

Outreach is an important factor for a project of this size. Harris supported OCTA’s public relations team during project activities. Innovative communication tactics included interactive maps showing planned improvements, a project mobile app featuring key milestones, and a partnership with Waze to capture real-time road closures and user-powered reports.

To help minimize disruptions and frustrations, Harris was also focused on specialized communications with area businesses. To date:

  • More than 1,200 businesses have been contacted
  • 60% of businesses signed up to receive notifications about the project
  • More than 500 employers are willing to share information with customers
  • 8 dedicated street team members met one-to-one with business owners

Meet the Team

Vijay Desai, PE, QSD/P

Vijay Desai, PE, QSD/P

Vice President / Program + Construction Management


Orange County Transportation Authority


Orange County, CA




Construction Management

I-405 Improvement Project Wins Major ASCE OC Award


I-405 Improvement Infographic