I-405 Sepulveda Pass Improvements Program

Los Angeles, California


Design-build delivery accelerates the massive job of widening the nation’s most congested interstate


• Capacity is enhanced with a 10-mile HOV lane
• Project is Southern California’s largest-ever design-build highway improvement project
• Three bridges erected in unprecedented time

HNTB served as lead designer on the design-build team implementing the massive I-405 Sepulveda Pass Improvements Project. HNTB’s scope of work included utilities, bridges, intelligent transportation systems, landscaping, maintenance of traffic, and other project criteria.

Los Angeles’ Interstate 405 is the nation’s busiest interstate. The Los Angeles County Metropolitan Transportation Authority and the California Department of Transportation envisioned the project as a way to loosen iconic L.A. congestion by adding a 10-mile high-occupancy vehicle lane to the northbound side of I-405 between the I-10 and U.S. 101 highways.

Coordination was critical in developing efficient staging schemes compatible with compliant traffic handling plans. HNTB also expedited the project by using mobile LiDAR to condense surveying to just 12 hours over three nights, employing innovative technologies to accelerate bridge erection, and preventing the mother of all traffic jams – “Carmageddon” – through a massive traffic management initiative and public awareness campaign.