SR-55 Improvement Project Enters Final Major Construction Phase with Upcoming Traffic Shift

Drivers will begin using new freeway lanes as early as Oct. 26, allowing crews to finalize second carpool lane and reconstruct center median; project on track for completion in late spring 2027

ORANGE - A major improvement project along one of Orange County's busiest freeways is entering its final major phase of construction, with drivers soon shifting onto new lanes of State Route 55 between I-405 and I-5, so new carpool lanes can be built.

Beginning as early as Monday, Oct. 26, crews will begin shifting northbound traffic onto lanes along the outside of the freeway, marking the first time drivers will use the new lanes.

The shift will allow crews to begin demolishing and reconstructing the freeway's center median to accommodate new carpool lanes in both directions.

The work marks a significant milestone for the approximately $506 million SR-55 Improvement Project, which is expected to be completed by late spring 2027.

To prepare for the traffic shift, crews will restripe lanes and install concrete barriers to separate drivers from the center median work area. Intermittent nighttime lane and ramp closures will be necessary from approximately 9 p.m. to 5 a.m., beginning as early as Oct. 26 and continuing for approximately two weeks. Similar work will follow in the southbound direction, with some activities potentially overlapping.

The traffic shift will also bring a permanent change to the northbound SR-55 on-ramp at McFadden Avenue. Once restriping is completed in that area, drivers entering the freeway from McFadden Avenue will only be able to access northbound I-5. Access to northbound SR-55 and southbound I-5 will no longer be available from that on-ramp, and drivers traveling in those directions will need to use alternate routes.

The center median reconstruction is expected to take approximately six months and represents the last major construction activity before project completion. All major structures, including freeway bridges and retaining walls, are expected to be completed by the end of this year.

Project overview

Led by the Orange County Transportation Authority in partnership with Caltrans, the project is improving approximately four miles of SR-55 between I-405 and I-5 through Irvine, Santa Ana and Tustin. The improvements include adding one regular lane and one carpool lane in each direction, along with new merge lanes to help drivers enter and exit the freeway more smoothly.

The upcoming traffic shift follows years of extensive construction along the corridor, including widening freeway bridges, constructing retaining walls, relocating utilities, improving ramps and rebuilding drainage infrastructure. The project also includes new sound walls, overhead signs and lighting. The new carpool lanes will feature continuous access, allowing drivers to enter and exit more easily.

SR-55 is a vital north-south connection linking central Orange County with coastal communities and major employment centers. More than 260,000 vehicles travel this stretch of freeway daily, with traffic expected to grow to nearly 275,000 vehicles by 2040.

The project is funded through a combination of local, state and federal sources, including $140 million in competitive state transportation funding awarded by the California Transportation Commission. Additional funding comes from Measure M, Orange County's voter-approved half-cent sales tax for transportation improvements, and other state and federal sources.

As construction enters its final major phase, OCTA and Caltrans will continue working to minimize impacts on drivers and nearby communities while keeping safety a top priority. Drivers are encouraged to use caution, watch for changing traffic patterns and allow extra travel time. Construction schedules are subject to change because of weather or unforeseen conditions.

Drivers can find the latest information about traffic shifts, lane closures and detours, including alternate routes for the McFadden Avenue on-ramp, and sign up for construction alerts at www.octa.net/sr55.

Meet the Team

Media Contacts

Resources

About

The Orange County Transportation Authority's Public Information Office responds to media inquiries, issues press releases and provides information about OCTA to the public and stakeholders.