West County Connecter

The Project.

By linking high occupancy vehicle (HOV) lanes from the I-405 to SR-22 and to the I-605, drivers now have a seamless carpool connection to relieve congestion on the busiest section of freeway in the nation. Other project elements include adding a second carpool lane in each direction on the I-405 between the SR-22 and the I-605, reconstructing six bridges, building two new bridges, and reconstructing on- and off-ramps and up to 26’-tall retaining walls.


Orange County Transportation Authority/CALTROP


Orange County and Los Angeles County, CA


  • Geotechnical Testing
  • Materials Testing

Project Fact:

Congestion relief on the busiest section of freeway in the nation.

The Leighton Solution.

Leighton provided soils and material testing services in accordance with California Test Methods and ASTM requirements.

Our Caltrans-certified technicians provided periodic field and materials testing for Engineer’s Acceptance. Working under the roadway and structural inspectors, who act on behalf of the project’s Resident Engineer, our duties included quality assurance of the methods and frequencies for performing testing and inspection; random field testing of soils, aggregates, and Hot Mix Asphalt (HMA); and full-time field testing of structural Portland Cement Concrete (PCC). Construction materials testing is performed in Leighton’s Caltrans-certified lab to verify contractor compliance with Caltrans specifications.

The 6-mile project traverses the cities of Garden Grove, Westminster, Seal Beach, Los Alamitos, Long Beach, and the community of Rossmoor.