California Builder & Engineer

Dedicated to the people who make our built environment better and safer. We tell your stories and celebrate your successes.

Register with us and receive industry news and content only available to subscribers.


Indianapolis, IN, USA (HQ)

903 E. Ohio St., Indianapolis, IN 46202

Call: (317) 423-2325

Orange County I-5 Project Adds New Carpool Lanes to Busy Corridor

by: Mark Bird
Crews use a Caterpillar excavator to remove concrete barriers between carpool and regular lanes on I-5 in Orange County.
Crews use a Caterpillar excavator to remove concrete barriers between carpool and regular lanes on I-5 in Orange County.
With the completion of the I-5 Central County Improvements Project, an essential transportation link in the central part of Orange County now generates less traffic congestion, fewer bottlenecks, and improved traffic operations along the section of I-5 between SR 55 and SR 57.

The Orange County Transportation Authority (OCTA), in partnership with Caltrans, added a second carpool lane in each direction on this corridor within the cities of Santa Ana, Orange, and Tustin. The project also included removal of the I-5/Main Street High Occupancy Vehicle (HOV) on- and off-ramps. Additionally, the concrete barriers between the carpool and regular lanes have been removed and the carpool lanes have been striped for continuous access, allowing drivers to move freely between the lanes.

Approximately 380,000 drivers travel through this area near Santa Ana, Tustin, and Orange every day, and traffic is expected to increase to nearly 400,000 vehicle trips by 2035. The corridor is a crucial connection to local job and retail centers, and is an important commercial route as well. The existing HOV lanes were constructed nearly 30 years ago; motorists have frequently experienced traffic congestion on the I-5 freeway between SR 55 and SR 57, and delays were likely to grow along with the projected increase in traffic.

The project's environmental phase was completed in April 2015, and the final design phase in late 2017. Construction began in March 2019 and the existing I-5/Main Street carpool bridge was demolished in August 2019. The project was essentially complete by the end of 2020.

The primary contractor on the I-5 Central County Improvements Project was OHL. Among the other project partners were TRC Companies, construction management consultant; TY Lin International, designer consultant; Hill International, outreach support consultant; and AECOM, environmental phase consultant.

Federal Funding Augmented By County's OC Go Initiative
The $39 million project was funded with federal dollars and by Measure M, also known as OC Go, Orange County’s half-cent sales tax for transportation improvements. As OCTA CEO Darrell E. Johnson explains, “The funds from Measure M helped OCTA leverage federal funds, which made up the majority of project funding. The total project funding included $34 million in federal funds and $5 million in local sales tax funds.”
Your local Trimble Construction Division dealer
SITECH Southwest

“The project was identified as an important improvement to Orange County’s overall transportation network through Measure M2, Orange County’s half-cent sales tax for transportation improvements,” says Johnson. “The measure was originally approved in 1990 and overwhelmingly renewed with 70 percent of the vote in 2006. The measure helps fund all transportation in Orange County with 43 percent of funding going to improve freeways, 32 percent to local streets and 25 percent to public transit.”

Johnson states that OCTA’s responsibilities, programs and services impact every aspect of transportation within the state’s third largest county. “Since its formation in 1991, OCTA has kept residents and commuters moving throughout the 34 cities and unincorporated areas of Orange County. After experiencing the success and progress of the original Measure M, nearly 70 percent of voters renewed the half-cent sales tax in 2006 to launch OC Go, as the measure was re-branded to raise awareness. The OC Go name and logo is consistent with other OCTA brands including OC Bus, OC Streetcar, OC Bike, OC Vanpool, and OC Metrolink.”

Lower Pandemic Traffic Volumes Helped Keep Project on Schedule
Johnson reports that a few major factors helped keep the project moving forward and open ahead of schedule. “Extra safety precautions were taken in the field because of the COVID-19 pandemic.  At the same time, reduced traffic volumes helped crews access more of the freeway for longer periods of time. Most of the work was able to be completed by the summer of 2020.”

He adds that during the early part of Summer 2020, the state’s stay-at-home orders related to the pandemic – and reductions in traffic numbers on I-5 – allowed Caltrans to approve closing the existing HOV lanes in both north and southbound directions for approximately two months.  This allowed the construction contractor much more access to the central area of I-5 so that drainage, median barrier, striping, and signage work could be completed ahead of schedule.

“Also, earlier in the construction, project plans and specifications had allowed up to nine weeks to demolish the Main Street HOV drop ramps,” he continues. “Caltrans approved full closure of the I-5 for one weekend in August 2019 and the contractor was able to demolish the drop ramps in one weekend. Excellent partnering between OCTA, the contractor, Caltrans, consultants, the City of Santa Ana, Metrolink, and California Highway Patrol helped expedite the schedule.”

Upgrading 1950s Era Interstate Segment Presented Challenges
Even as the project proceeded smoothly, it was not without a few particular construction challenges, Johnson points out. “This portion of Interstate 5 was built in the 1950s and since then, several improvement projects added lanes, drop ramps, electrical, and drainage facilities. Because of this, there were a number of features that were different in the field than what was known or shown on written plans.  These varying site conditions resulted in numerous requests for information from the contractor, who worked in close coordination with OCTA and the designer to ensure that any needed changes did not delay construction of the project.  

“It’s important to note that there were no claims on this project, which won the Caltrans Excellence in Partnering – Gold Award.”

Deere CE
Your local Deere & Co dealer
Coastline Equipment

The existing northbound and southbound HOV lanes on I-5 “threaded” under existing railroad tracks, Johnson reports. To minimize impacts to the railroad operations, and essentially leave the railroad bridge alone, the two (one existing and one new) southbound HOV lanes were placed where the previous HOV lanes had been and the northbound side of the freeway was shifted to the east.  

This necessitated construction of a long retaining wall under the abutment of the railroad bridge.  This retaining wall was constructed utilizing tie-backs and soil nails.  The work required close coordination with railroad officials to ensure that the structural integrity and operations of the railroad were successfully maintained at all times.

Communication with Public was Essential
Such a complex project warranted extensive and coordinated public outreach. Johnson says that OCTA began communications with the public approximately one year prior to construction. The goal was to raise awareness about the project and the activities that would affect the community – including light, noise, dust, and impacts from large vibrations.

“We tailored our approach to specific construction activities such as building retaining walls behind a neighborhood tract; demolishing the HOV carpool ramp near the Discovery Cube and Park Santiago community; and communicating emergency daytime closures that affected hundreds of thousands of commuters along this segment of I-5.”

OCTA communicated updates through postcards, fliers, and press releases, and also through social media platforms, an interactive Google map, and text alerts. Weekly construction alerts were sent out and a project website was routinely updated. Key stakeholder briefings were set up with businesses and emergency responders and OCTA arranged targeted neighborhood presentations, as well as attending community events to proactively distribute information about the project. OCTA and Caltrans also partnered with the City of Santa Ana, which issued advisories regarding construction activities.

Corridor Ready to Meet Demands of Projected Traffic Increase
The completion of the I-5 Central County Improvements Project has not only improved the heavily-traveled corridor between SR 55 and SR 57 for the thousands who use it daily; it has also prepared the route to handle the increased traffic that is destined to come. The enhanced functionality and traffic flow in all of the HOV lanes should also encourage more people to carpool, Johnson says.

“Every major freeway project like this takes close coordination among team members. The teamwork on this project between OCTA, Caltrans, the contractors and all partners was essential during a public health crisis and everyone rose to the challenge to not only overcome the obstacles, but deliver a project that was on budget and ahead of schedule. Additionally, by enhancing our HOV network, we encourage carpooling and improve air quality, which in turn positively impacts the environment for the entire region.”  

Your local Trimble Construction Division dealer
SITECH Southwest

Steve Jones, OCTA Chairman and Mayor of Garden Grove, adds, “I’m proud that despite the challenging year 2020 was, we are able to continue delivering our promises to Orange County taxpayers by bringing relief to those who travel along this stretch of the I-5. A big thanks goes to all the essential workers for their efforts to help bring these benefits to the public early. As an organization, we worked diligently to proactively address the unprecedented challenges of this public health crisis. I’m proud of OCTA staff and our Board of Directors for accomplishing so much toward providing essential transportation improvements and services for Orange County.”

Your local Trimble Construction Division dealer
SITECH Southwest
Your local Trimble Construction Division dealer
SITECH Southwest
Your local Gomaco dealer
Terry Equipment