Not only is Interstate 405 one of the busiest highways in the nation, but the 16-mile section of it in Orange County, Calif., runs through nine cities or communities and at an angle through the urban landscape. But the design-build team managed to complete the $2-billion I-405 Improvement Project on time and budget, improving driving conditions for some 400,000 daily motorists.

The Orange County Transportation Authority (OCTA), in partnership with the California Dept. of Transportation (Caltrans), oversaw the project (ENR CANW 6/12-19/23 p. 44). The project’s centerpiece, the 405 Express Lanes, combats gridlock while generating revenue for future transit improvements. Eighteen bridges were rebuilt or widened to modern standards, enhancing safety and preparing for future traffic needs.

Photo courtesy OCTA

Right-of-way (ROW) acquisition delays were a significant challenge. OCTA implemented a federal and state-approved incentive payment program, “Sign in 60,” which offered property owners a 20% incentive above the appraised value if an agreement was reached within 60 days.

OCTA’s board also approved modified settlement delegation specific to this project, granting staff more flexibility in settling agreements. Contingencies were built into the schedule for eminent domain actions and other unexpected issues, ensuring the design-builder had conservative parcel availability dates.

Photo courtesy OCTA

The design-build team used four haunched bridges on the project, says Pierce Homer, transportation director for Moffat & Nichol. “This approach reduced rights-of-way [needs] and wall heights near those bridges, reducing costs.”

A haunched bridge meets clearance requirements by being thicker near the bents and thinner near the abutments while maintaining overall structural strength.

Sustainable Investing

OC 405 Partners was required to develop a sustainability management plan and chose the Federal Highway Administration’s (FHWA) INVEST (Infrastructure Voluntary Evaluation Sustainability Tool). INVEST is a web-based self-evaluation tool comprised of voluntary sustainability best practices, which cover the lifecycle of transportation services.

OCTA project team received an update every six months to score against the plan. “This process routinely reinforced our sustainability priorities,” says an OCTA spokesman.

The project adhered to Caltrans guidelines by using native, drought-tolerant plants and maximizing the use of reclaimed water. Fly ash and rubber tires were used in concrete mixes, and new pavement includes recycling reclaimed asphalt pavement and recycled concrete aggregate. More than 700,000 tons of concrete were recycled and reused.

OCTA implemented executive partnering sessions with leadership from Caltrans and OC 405 Partners and Caltrans. These meetings were held quarterly and then went monthly during key periods of the projects.

“Like any megaproject, we encountered challenges,” says OCTA CEO Darrell E. Johnson. “Being a part of routine check-ins, developing trust with our partners and celebrating our successes helped keep the project moving forward in a positive manner.”