Skip to main content

I-405 (I-5 to SR-55)

I-405 (I-5 to SR-55)

Caltrans and OCTA are proposing improvements to the I-405 between I-5 and SR-55 to address freeway congestion and make travel more efficient.

OCTA and OCGO Logo DarkBlue

Project Overview

Currently in the Project Approval/Environmental Document (PA/ED) phase, commonly referred to as the environmental study phase, OCTA and Caltrans have studied the potential benefits and effects of adding one or two general-purpose lanes in each direction, adding auxiliary lanes and making various operational improvements. The environmental study phase was completed in 2018.

About the Project Area

Interstate 405 between I-5 and SR-55 plays a central role in progressing Orange County’s mobility, economy and quality of life. This section of I-405 provides direct and indirect access to residential communities, employment centers, cultural and recreational facilities, John Wayne Airport, and some of the region’s top medical and academic institutions.

This 8.5 mile segment of I-405 is one of the busiest stretches of freeway in the nation, as well as one of the most congested. Forecasted local and regional traffic demand is expected to increase about 15%, resulting in 255,000 and 291,000 vehicles per day by 2050. To address current and future travel demand on this corridor, OCTA and Caltrans District 12 are studying the I-405 South Improvement Project.

Proposed Improvements

Three alternatives are currently under consideration, one No Build Alternative and two Build Alternatives. The No Build Alternative includes no improvements from the proposed project but assumes completion of other planned improvements in the study area that are currently underway by Caltrans. The Build Alternatives would increase capacity and ease merging operations by adding one or two general-purpose lanes in the northbound and southbound directions. Both Build Alternatives also propose the realignment of ramps, changing the existing limited carpool lane access to continuous access, as well as numerous operational improvements.

The Environmental Review Process

The I-405 (SR-55 to I-5) Improvement Project is currently in the Project Approval and Environmental Document (PA/ED) Phase, commonly referred to as the environmental study process. As mandated by the California Environmental Quality Act (CEQA) and National Environmental Policy Act (NEPA), an Initial Study and Environmental Assessment (IS/EA) environmental document was prepared.

At the heart of CEQA and NEPA is the public’s interest in the environment. In general, the purpose of the environmental review process is to identify a proposed project’s potential environmental effects and to develop measures to avoid, minimize and/or mitigate these effects.

The IS/EA will assess a wide range of topics including, but not limited to: air quality, noise, natural environment, community impacts, visual impacts, relocation impacts, cultural resources, water quality, floodplain impacts, and paleontological resources. A Draft IS/EA comprehensively details information of each study, and is available for public review and comment during a public review period from Nov. 14, 2017 through Dec. 15, 2017. A public hearing was held on Dec. 5, 2017 during the public review period at University Community Park in Irvine.

project approval steps

Project Study Report–Project Development Support

The Project Study Report–Project Development Support (PSR-PDS) was approved by Caltrans on December 10, 2013. The PSR-PDS is a preliminary planning document and describes the transportation problem, identifies the scope of viable alternatives, and provides an estimate of the project development support resources required. A Preliminary Environmental Assessment Report (PEAR) was also prepared as part of the PSR-PDS.

Studies indicate the proposed project will not significantly affect the quality of the environment.

A draft environmental document was prepared which evaluates the project’s potential benefits and effects. This document was circulated for public review and comment from November 14 through December 15, 2017. Although the public comment period has passed, you may continue to view the draft environmental document in the link below.

During the public review period, the draft environmental document was available at the following locations:

  • Caltrans District 12; 1750 East 4th Street, Suite 100; Santa Ana, CA 92705

  • Heritage Park Branch Library; 14361 Yale Avenue; Irvine, CA 92604

  • Mesa Verde Branch Library; 2969 Mesa Verde Drive E; Costa Mesa, CA 92626

  • El Toro Branch Library; 24672 Raymond Way; Lake Forest, CA 92630

Public Hearing (Open House Format) Held on December 5, 2017:

Caltrans and OCTA held a public hearing (open house format) on Tuesday, December 5 at University Community Park in Irvine for members of the community to learn about the proposed project improvements, meet the project team, ask questions, and submit comments.