I-405 Improvement Project

This project featured the fast-tracked design and construction of 16 miles of two new lanes in each direction of the interstate highway I-405 in Orange County, California, from Costa Mesa to Los Angeles County. The OHLA USA-led design-build joint venture -- known as OC 405 Partners -- performed this $1.5 billion assignment for the Orange County Transportation Authority and Caltrans.

The effort has added one new general-purpose lane in each direction and a second lane in each direction that combined with the existing carpool lanes to create the 405 Express Lanes along the corridor between State Route 73 and Interstate 605. along with improvements to freeway entrances, exits, bridges, and several auxiliary lanes. 

Key elements of the project, which stretches from Costa Mesa to the Los Angeles County line, include a total of 18 bridges that were demolished and reconstructed, many with new sidewalks and added bike lanes. The project team added ramps, upgraded drainage, and relocated utilities, in addition to constructing and installing hundreds of retaining and soundproofing walls. The massive undertaking was one of the most significant infrastructure contracts underway in the western United States.

The project met many sustainability objectives including the recycling of 710,000 tons of concrete, which was reused for the base layer of the new lanes. In addition to reducing emissions, the effort improves travel reliability by eliminating bottlenecks, resulting in fewer traffic delays. It is estimated that commute times are reduced by half for nearly 400,000 daily drivers.