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I-405/I-605 HOV Connector

TRC designed the widening of Interstate 405 to accommodate an additional HOV lane in each direction of a freeway segment that carries over 415,000 cars daily.​

Orange County Transportation Authority

Project Location:
Seal Beach, California

Project of the Decade

Project Challenges

TRC was selected by the Orange County Transportation Authority (OCTA) to design the widening of Interstate 405 to accommodate an additional HOV lane in each direction on I-405 between SR-22 and I-605. This freeway segment carries over 415,000 cars daily. This high profile project included six bridges, a reconstruction of the Seal Beach Boulevard interchange, and multiple retaining walls and soundwalls. The HOV Connector is a half-mile long structure connecting the HOV lane on I-405 to the HOV lane on I-605.​


The HOV connector was constructed in the median of the freeway, and required 26’ high retaining walls. Traditional cantilever retaining walls could not be used due to their construction footprint, so MSE walls were considered. However, due to poor soil in the area, the weight of the fill would impact the existing roadway. Instead, TRC used an innovative approach which incorporates lightweight fill and precast panels for the structure approach.

Because the structures were designed to accommodate the ultimate future widening, it resulted in longer structure spans and eliminated the possibility of using multiple-span structures. This particularly impacted the Seal Beach Boulevard Bridge which was originally designed as a 5-span bridge, but had to be redesigned as a 2-span bridge with a long span of 254’. This span length in turn required a 10’-6” deep prestressed box girder which resulted in high prestressing forces.
Maintaining all freeway lanes for the existing traffic was crucial during construction, so extensive stakeholder coordination was required, including interface with OCTA, Caltrans, and seven affected cities.
Design for the project was initiated in October 2007 using an accelerated design schedule. The design effort encompassed 38 engineering reports and over 1,850 plan sheets. Construction will begin in June 2010 and is anticipated to last four years.


Please visit the OCTA Website for more information.

TRC Honors the CC Myers, Inc. with a Top Project of the Decade Award
In this Photo: (Starting from left)

Kenneth OH – OCTA PM for the construction of I-405/ I-605 Connector; Ayman Salama - TRC; David Zarider – TRC, Ross Lew - TRC; Will Kempton – OCTA CEO; Niall Barrett – OCTA Project Manager for the PS&E; Rose Casey – OCTA Program Manager; Christina Byrne - OCTA Public Outreach Manager; Tom Bogard – OCTA – Director of Highway Design & Construction

TRC Honors the Orange County Transportation Authority with a
Top Project of the Decade Award