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 the following social media sites:
Facebook facebook.com/405Improvement
and on Twitter OCTA Twitter and Instagram at: OCTA Instagram Link

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 Activity in Fountain Valley - What's Happening Now?

November 19 - November 21, 2018 - Weekday Night Time Work - 10 p.m. to 5 a.m.

  • FULL CLOSURE of SB Brookhurst St CD Road Off-Ramp from SB I-405
  • FULL CLOSURE of SB Brookhurst St On-Ramp onto NB I-405
  • NB Warner Ave On-Ramp onto NB I-405

Pile driving near the Slater Avenue bridge is anticipated to begin Monday, Nov. 19 and to continue over the next several weeks. Activities will occur adjacent to Slater Avenue on the northbound and southbound sides of I-405, weekdays from 6:30 a.m. to 3:30 p.m. Pile driving is necessary to construct the foundation of the new Slater Avenue bridge. 

*Please be advised that this work may be loud. Dates and times are subject to change due to unforeseen operational factors or inclement weather. 

FULL CLOSURE of Slater Avenue Bridge for Demolition:

Road Detours:

WB Route-NB Brookhurst St left turn onto WB Warner Ave left turn onto SB Bushard St to WB Slater Ave

EB Route - SB Bushard St left turn onto EB Talbert Ave left onto NB Brookhurst St to EB Slater Ave

  • Road Detours: SB I-405 Warner Ave. Off-Ramp, EB Warner Ave., Brookhurst St.
  • Road Detours: SB I-405 Warner Ave. Off-Ramp, EB Warner Ave., Brookhurst St.
  • FULL CLOSURE SB I-405 Off-Ramp onto SB Brookhurst St
  • FULL CLOSURE SB I-405 Off-Ramp onto SB Brookhurst St
  • FULL CLOSURE SB Magnolia St On-Ramp onto SB I-405
  • FULL CLOSURE SB Magnolia St On-Ramp onto SB I-405
  • FULL CLOSURE SB Magnolia St On-Ramp onto SB I-405
  • SB I-405 from Warner Ave to Brookhurst St
  • SB I-405 from Warner Ave to Brookhurst St
Slater bridge sign
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.

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 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

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.