TRC was selected by the Orange County Transportation Authority (OCTA) to develop Plans, Specifications, and Estimates (PS&E) and provide construction support for the Western Segment of the West County Connectors Project which widened I-405 to accommodate an additional HOV lane in each direction with direct HOV connection to I-605. This major connection between Orange and Los Angeles Counties is the busiest section of freeway in the nation, with an average daily traffic volume of over 370,000 vehicles and projections of 430,000 in 2035 through the cities of Long Beach, Seal Beach and Los Alamitos, and the community of Rossmoor. This connector is also an important truck route and an integral part of Southern California's freeway network, thus providing motorists with access to John Wayne Airport, Long Beach Municipal Airport, Los Angeles International Airport and the Port of Long Beach.
The $102 million construction contract to complete the 5-mile long Western Segment of the project, for which TRC was responsible, represents the largest such contract awarded by OCTA to date and includes the following major components:
Challenged by poor soil conditions in the area, TRC staff applied an innovative approach that incorporated lightweight concrete fill and precast panels to facilitate the construction of 26’ high retaining walls that were needed support the approach to the I-405/I-605 HOV direct connector bridge that was constructed in the median of the freeway. Maintaining all freeway lanes and minimizing the impact to Seal Beach Boulevard was also crucial during construction. To maintain traffic, an extensive stage construction scheme was developed and implemented, along with the maintenance of close coordination with stakeholders that included on-going interface with OCTA, Caltrans, and seven affected cities.
Design for the project was initiated using an accelerated design schedule and resulted in the development of 38 engineering reports and over 1,900 plan sheets.
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