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

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  • SR-55 (I-405 to I-5)

    Project Contacts 1 of 2

    Associate Community Relations Specialist

    (714) 560-5766
    Detours will be posted once the project reaches the construction phase.
    Detours will be posted once the project reaches the construction phase.
    Stay Informed

Overview Tab Content:

  • Project Overview

    The Costa Mesa Freeway (SR-55) is one of the most heavily congested freeways in Southern California. The SR-55 is a vital link to other major freeway systems in Orange County, and it is the only freeway providing a direct north-south connection between Central Orange County and the coastal region. Currently, the SR-55 between Interstate 405 (I-405) and Interstate 5 (I-5) has four general purpose lanes, one carpool lane and some auxiliary lanes in each direction. The heavy congestion on SR-55 is expected to increase with future demand. This project is proposing to add new lanes to this stretch of the freeway to reduce congestion and increase capacity.

    Notice of Availability: Final Environmental Document

    The California Department of Transportation (Caltrans) District 12, in cooperation with OCTA, proposes to widen SR-55 in both directions from just north of the Interstate 405 (I-405)/SR-55 Interchange to just south of the Interstate 5 (I-5)/SR-55 Interchange through the cities of Santa Ana, Tustin, and Irvine.

    This is a notice of availability of the Initial Study with Mitigated Negative Declaration/Environmental Assessment with Finding of No Significant Impact for this project. A copy of the final environmental documents can be seen at:

    Final design of the project is underway, and construction is scheduled to begin in mid-2021.

Details Tab Content:

  • About the Project

    The SR-55 between I-405 and I-5 has four general-purpose lanes and one continuous-access carpool lane in each direction. OCTA and Caltrans conducted an environmental study for a project to add new lanes to the 4-mile stretch of SR-55 in northbound and southbound directions, between I-405 and I-5. Based on the study, the selected alternative is:

    • Alternative 3 Modified – Add one general purpose lane, one carpool lane and auxiliary lanes in each direction

    Purpose and Need

    The purpose of the proposed project is to:

    • Improve mobility and reduce congestion;
    • Improve traffic operations; and
    • Increase capacity.

    The project is needed due to:

    • Limited available lane capacity during peak periods;
    • Inadequate merging distances as a result of closely spaced on- and off- ramps along the freeway mainline; and
    • Non-standard lane and shoulder widths at some locations.

    Anticipated Schedule

    Community Outreach

    The SR-55 Project Outreach Team is available to make a presentation to your neighborhood, organization or business. Please contact us with requests, questions or comments at or 800-724-0353. Or, sign up for our project email alerts by selecting the Stay Informed tab at the top of this page.

Detours Tab Content:

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SR-55 Improvements
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