I-405 Improvement Project

Currently, the San Diego Freeway (I-405) is one of the most congested freeways in Orange County, carrying more than 300,000 vehicle trips in some sections each day. By 2040, traffic volumes on the I-405 are expected to increase significantly. The I-405 Improvement Project will increase freeway capacity, improve traffic and interchange operations, and enhance road safety to meet state and federal standards.

The Orange County Transportation Authority (OCTA) in cooperation with The California Department of Transportation (Caltrans) is widening the San Diego Freeway (I-405) between State Route 73 (SR-73) and Interstate 605 (I-605). The I-405 Improvement Project will improve 16 miles of the I-405 and includes the addition of one regular lane in each direction from Euclid Street to I-605, as well as improvements to freeway entrances, exits and bridges. It will also include the construction of the 405 Express Lanes, which will incorporate the existing carpool lanes and consist of two lanes in each direction from SR-73 to I-605. Solo drivers will pay a toll to use the 405 Express Lanes, but carpoolers will be able to utilize the lanes for free. 

I-405 Improvement Project Map


For More Information...

Visit OCTA’s website at www.octa.net/405improvement for up-to-date information about the project and to sign up to receive updates and alerts. You can also follow the project on Facebook (facebook.com/405Improvement) and on Twitter (@405Improvement).  

If you have specific questions about the I-405 Improvement Project, you can contact OCTA's I-405 Community Relations division directly by phone at (888) 400-8994 or email at 405project@octa.net

I-405 Improvement Project Update - March 2017

The OCTA Board of Directors awarded the I-405 Design-Build contract to OC 405 Partners on November 14, 2016.  The Orange County Transportation Authority (OCTA) in partnership with The California Department of Transportation (Caltrans) will start construction on the I-405 Improvement Project in late 2017. The project will include:
  • One new regular freeway lane in each direction
  • Two 405 Express Lanes in each direction
  • 18 bridge replacements
  • Interchange reconfigurations
  • Merge lane improvements
  • New and replaced soundwalls
  • New bike lanes and sidewalks on local streets/bridges

I-405 Bridge Construction Update - August 2017

OCTA recently released a preliminary bridge construction map showing when construction is anticipated to start on the bridges affected by the I-405 Improvement Project and which bridges will be closed during construction. (Click on the map to the right to enlarge the image.)

The City of Fountain Valley has seven bridges that will be affected by the widening of the I-405 freeway. Each of these bridges will need to be reconstructed to accommodate the freeway below. The Brookhurst, Slater, Warner and Magnolia bridges will remain open with a reduced number of lanes during construction. However, some bridges will need to be closed completely to traffic during construction, including the Ward, Talbert and Bushard bridges.

I-405 Interactive Map Pic

I-405 Improvement Project Launches Interactive Map - October 2017

OCTA recently launched a fully interactive, mobile-friendly resource for the I-405 Improvement Project.

Users can click on a location to see when construction is anticipated to start and find details on any current pre-construction activities planned in the area. The newly launched map currently features preliminary construction activities that are happening now.

When construction officially commences in early 2018, users can explore the project area in real time, view both planned improvements and current construction activities for each bridge, as well as, updated closure and detour information.

How Will the I-405 Improvement Project Impact Fountain Valley?

The I-405 Improvement Project will have a direct impact on traffic in Fountain Valley, both on and off the freeway. During construction, all seven bridge overcrossings in Fountain Valley will be taken down and replaced in a phased approach manner to minimize traffic impacts to the greatest degree possible. The affected bridges are on Ward Street, Talbert Avenue, Brookhurst Street, Slater Avenue, Bushard Street, Warner Avenue and Magnolia Street. Onramps and offramps throughout the City will also be improved. This construction will cause detours and traffic delays. Once construction starts, drivers are encouraged to stay informed so they can use alternate routes and to be patient with construction workers and fellow drivers. 

There are no full property acquisitions as part of the project. However, there are some locations along the 16-miles of the project where OCTA will require temporary construction easements or partial acquisitions. If you have questions, please contact Christina Byrne, OCTA's Community Outreach Manager, by calling (714) 560-5717 or emailing 405project@octa.net.


I-405 Improvement Activity in Fountain Valley - What's Happening Now?

In an effort to make travel easier for motorists during the Thanksgiving holiday weekend, pre-construction activities will be suspended Wednesday afternoon, November 22, thru Friday, November 24, 2017. Pre-construction activities will resume on Monday, November 27, 2017.

November 20-22, 2017 - OCTA's contractors will be conducting drill exploration and ADL sampling activities along the NB and SB shoulders, on- and off-ramps of the I-405 freeway, and local streets at the following locations:
Nighttime Work - 9 p.m. to 5 a.m. 

  • SB I-405 on-ramp from Euclid Street and SB I-405 right lane from Ward Street to Euclid Street
  • NB I-405 right two lanes from Harbor Boulevard to Talbert Avenue
  • NB I-405 Warner Avenue to Magnolia Street collector road
  • NB I-405 to WB Warner Avenue off-ramp
  • NB I-405 to NB Magnolia Street off-ramp
  • NB Euclid Street on-ramp

Please be advised that these activities may be loud.