San Diego Freeway (I-405) Improvement Project

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Today, 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. Traffic volumes on the I-405 are expected to increase significantly and the population is expected to grow 11 percent by 2040.

The California Department of Transportation (Caltrans), in cooperation with the Orange County Transportation Authority (OCTA), is proposing to widen the San Diego Freeway (I-405) between State Route 73 (SR-73) and Interstate 605 (I-605). The purpose of the proposed improvement is to improve travel conditions for work, recreation, school, and commerce by increasing freeway capacity, improving traffic and interchange operations, and enhancing road safety to meet state and federal standards. The I-405 Improvement Project is partially funded by Measure M Orange County’s half-cent sales tax for transportation improvements.

Board Takes Steps to Ensure Local Control of I-405 improvements
On February 9, 2015, the OCTA Board of Directors (Board) directed CEO Darrell Johnson to re-engage in discussions with Caltrans regarding the design-build cooperative agreement on the I-405 Improvement project and return to the Board with an option for OCTA to proceed as the lead agency for the full implementation of the Caltrans project preferred alternative.

That option for Board consideration, expected within 60 days, would include policies required for operations, management and use of excess revenue for the planned high-occupancy (HOT) lanes. The Board’s action comes after Caltrans was able to secure $82 million to begin implementation of the HOT lanes. The HOT lanes had previously been planned as a second phase of the project after OCTA added one regular lane in each direction, as promised to voters in Measure M.

The full project preferred alternative selected by Caltrans in the environmental process in July 2014, calls for one general-purpose lane in each direction and an additional lane in each direction to be combined with the existing carpool lane to create a dual tolled express lane.

Caltrans’ Preferred Alternative Recommendation
On July 24, 2014, OCTA was informed that Caltrans recommends building Alternative 3, potentially using a phased implementation approach.

As part of Phase 1, OCTA would construct one general-purpose lane on the San Diego Freeway (I-405) in each direction between Euclid Street and the San Gabriel River Freeway (I-605). This will allow OCTA to move forward on the freeway improvement project that was promised to voters in Measure M. All of the Measure M Project K funding would be directed toward adding the one general-purpose lane. As part of Phase 2, Caltrans will pursue funding and ultimately construct an additional lane in each direction that would combine with the existing high-occupancy vehicle lane to operate as high-occupancy toll lane facility.

Project Alternatives
The I-405 Improvement Project draft environmental impact report/impact statement (EIR/EIS) was released on May 18, 2012 and included a no build and three build alternatives. Any project built will include at least one free lane in each direction as part of the I-405 Improvement Project that is funded through Measure M, the county’s half-cent sales tax for transportation.

No-Build Alternative

  • The No-Build alternative leaves the I-405 in its existing configuration with no additional lanes or interchange improvements.

Alternative 1: Add one general purpose (GP) lane in each direction

  • Alternative 1, the Measure M2 (M2) Project K as approved by the voters, adds one GP lane in each direction on the I-405 from Euclid Street to the Interstate 605 (I-605) interchange.

Alternative 2: Add two GP lanes in each direction

  • Alternative 2 is the M2 Project K with the addition of a second GP lane in the northbound direction from Brookhurst Street to the State Route 22 (SR-22) / 7th Street interchange, and the addition of a second GP lane in the southbound direction from the Seal Beach Boulevard on-ramp to Brookhurst Street.

On January 26, 2009, the Orange County Transportation Authority (OCTA) Board of Directors (Board) approved the addition of Alternative 3 to significantly alleviate congestion and provide additional travel choices to commuters, as well as to help fund the overall Project during difficult economic times when M2 sales tax forecasts were dropping:

Alternative 3: Add one GP lane and one high-occupancy toll (HOT)/ express lane in each direction

  • Alternative 3 includes M2 Project K and adds a HOT/express lane in each direction on I-405 from State Route 73 (SR-73) to SR-22. The HOT/express lane would be combined with the existing high-occupancy vehicle (HOV) lanes, and these would be converted to HOT/express lanes providing two HOT/express lanes in each direction on I-405 between SR-73 and I-605. The westbound HOV connector from SR-22 to I-405 would also be operated as a HOT/express lane.

I-405 Schedule
The following schedule is under review following the February 9, 2015 Board action described above.

Public Review

May 18 to July 17, 2012

Supplemental Draft EIR/EIS Public Review

June 28 to August 12, 2013

OCTA Board Recommends Alternative 1

December 9, 2013

Caltrans Recommends Preferred Alternative

July 2014

Issue Design-Build Request for Qualifications

October 2014

Issue Design-Build Draft Request for Proposals

March 2015


February 2015

Issue Design-Build Request for Proposals

August 2015

Design-Build Award

April 2016

Design-Build Notice to Proceed

June 2016


2016 to 2021


Christina Byrne

Project Contact

Christina Byrne
Manager of Community Outreach
(714) 560-5717