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SR-55 (I-5 to SR-91)

The Costa Mesa (SR-55) Freeway is one of the most heavily congested freeways in Southern California, and future demand is only expected to increase congestion. This project proposes to improve mobility, help with traffic flow, and improve traffic operations.

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The SR-55 serves as a vital link to other major freeway systems within 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 5 (I-5) and State Route 91 (SR-91) has three to four regular lanes, one carpool lane and some merge lanes in each direction. 

About the Project

The project reduces congestion and improves traffic by adding one regular lane in each direction on SR-55 between I-5 and SR-22 and provide operational improvements at various locations on SR-55 between SR-22 and SR-91. The environmental phase of the project has been completed, and a Build Alternative was selected. The Project will:

  • Add one regular lane in each direction between I-5 and SR-22;

  • Modify southbound on- and off- ramps at Katella Avenue;

  • Modify southbound off-ramp at Lincoln Avenue; and

  • Modify northbound and southbound off-ramps at Fourth Street

Caltrans has approved the Final Environmental Document (FED), detailing the Preferred Build Alternative. To receive an electronic copy of the FED, please email

Project Schedule

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