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First Bridge Set to Open on I-405 Improvement Project in Orange County, Calif.


First Bridge Set to Open on I-405 Improvement Project in Orange County, Calif.

Posted: August 29, 2019 | Tradewinds

Drivers, pedestrians and cyclists traveling along Slater Avenue in Fountain Valley will see an easier commute starting Friday, after the bridge over the I-405 Freeway reopens to traffic, a major milestone for the $1.9 billion I-405 Improvement Project.

The Slater Avenue bridge was fully demolished in September and reconstructed in less than a year. It is the first of 18 bridges to be built, widened or replaced as part of the project, which will speed up travel times on I-405 between Costa Mesa and the Los Angeles County line, an area traveled by more than 370,000 vehicles a day. 

The I-405 Improvement Project, the largest highway project under construction in California, will add one regular lane in each direction, as promised to voters through Measure M, Orange County's half-cent sales tax for transportation improvements. The project also adds a second lane in the center of the freeway, which combined with the existing carpool lanes, will create the 405 Express Lanes. 

With the 405 Express Lanes, modeled after OCTA's successful 91 Express Lanes, solo drivers will have the choice to pay a toll to speed up their commute. The initial toll policy allows all three-person carpools to use the 405 Express lanes for free at all times and two-person carpools pay a toll only during rush hour. 

This 16-mile segment of I-405 is one of the most heavily traveled stretches of highway in the nation, and drivers routinely face severe congestion in both the regular lanes and carpool lanes. The project is critical to accommodate expected employment, population and housing growth throughout Southern California. 

The I-405 Improvement Project, set to be completed in 2023, is being funded with a combination of local, state and federal funds, including a $629 million federal Transportation Infrastructure Finance and Innovation Act (TIFIA) loan. The federal loan will save taxpayers approximately $300 million compared to traditional financing methods. 

OC 405 Partners, a team of firms led by OHL USA, Inc. and Astaldi Construction Corporation, is designing and constructing the project, the largest in OCTA's history.

Construction updates are available at or on the project's mobile app. To download the free app, search 405 Improvement in the App Store or Google Play.