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I-405 Improvement Project
OCTA in cooperation with Caltrans is widening the San Diego Freeway (I-405) between SR-73 and I-605.The project will improve 16 miles of I-405 between the SR-73 freeway in Costa Mesa and I-605 near the L.A. County line.
The project includes adding one regular lane in each direction between Euclid Street and I-605 and making improvements to freeway entrances, exits and bridges. In addition, the project will add the 405 Express Lanes, incorporating the existing carpool lanes and a new lane in each direction between SR-73 and I-605.
For more information, please contact the Outreach team by calling 888-400-8994 or visit their website.
Project updates surrounding the City of Los Alamitos:
February 1, 2022 Construction Alert: Crews will close the southbound (SB) I-405 on-ramp from Seal Beach Boulevard for approximately one month to accommodate the freeway widening.
The ramp is scheduled to close 10 p.m. Wednesday, Feb . 2, and is anticipated to reopen after approximately one month.
June 10, 2021 Construction Alert: Crews will continue to perform girder installation work for the Bolsa Chica Road bridge over I-405. The girders are the main horizontal support beams and are part of the superstructure.
This work will require SB and NB full freeway, lane, SB Bolsa Chica Road, and ramp closures.
Night One
• SB freeway closure is set for as early as 11 p.m. TONIGHT, June 10, to 5 a.m. Friday, June 11.
• SB Bolsa Chica and SB loop on-ramp closures are set for 10 p.m. TONIGHT, June 10, to 5 a.m. Friday, June 11.
Night Two
• NB freeway closure is set for as early as 11 p.m. Friday, June 11, to 5 a.m. Saturday, June 12.
• SB Bolsa Chica closure is set for 10 p.m. Friday, June 11, to 5 a.m. Saturday, June 12.
June 3, 2021 Construction Alert: Crews will install pre-cast concrete girders for the Bolsa Chica Road bridge over I-405. The girders are the main horizontal support beams, known as the superstructure, the abutments and center columns.
This work will require SB and NB full freeway, lane and ramp closures.
Night One
• SB freeway closure is set for as early as 10:30 p.m. Friday, June 4, to 7:30 a.m. Saturday, June 5
Night Two
• NB freeway closure is set for as early as 11 p.m. Saturday, June 5, to 8 a.m. Sunday, June 6
*If this activity has not been completed, during the timeframes above, work is anticipated to continue on Monday, June 7 from 11 p.m. to 5:30 a.m.
April 9, 2021 Construction Alert: Crews are set to close the Old Ranch Parkway on-ramp to the WB SR-22 for approximately eight months to realign it as part of the I-405 Improvement Project. Activities include demolition, excavation, grading, drainage and electrical system installation, concrete pours and asphalt paving.
Beginning as early as 10 p.m. Tuesday, April 13, for approximately eight months.
• Daytime work hours are 7 a.m. to 4 p.m.
• Crews may mobilize equipment as early as 6 a.m.
• Nighttime work hours are 9 p.m. to 6 a.m.
Motorists should expect delays and use alternate routes if possible. All closures and detours will be included in our interactive map (https://i405improvements.kleinfelder.com/), on our closure list and on the project website.
Please be advised that this work may be loud. Dates and times are subject to change due to unforeseen operational factors or inclement weather.
April 8, 2021 Construction Alert: Partial Lane Closures on Seal Beach Boulevard for Median Work. Crews will install temporary traffic signals at Seal Beach Blvd. and Lampson Ave. and at Seal Beach Blvd. and the northbound (NB) I-405 freeway ramps/Old Ranch Parkway.
Temporary traffic signal construction is anticipated to start as early as 10 p.m. Friday, April 9 for approximately two weeks on weeknights.
Seal Beach Blvd. and Lampson Ave. will be intermittently reduced to two lanes at the intersection for the duration of the work.
Nighttime work hours are 9 p.m. to 6 a.m.
March 26, 2021 Construction Alert: Crews will begin median removal activities on Seal Beach Boulevard between Lampson Avenue and Old Ranch Parkway. This work will require continuous lane reductions on Seal Beach Blvd. for the duration of the work.
The center median will be demolished, removed and reconstructed to allow for the addition of a second left-turn lane from southbound (SB) Seal Beach Blvd. to the northbound (NB) I-405 on-ramp.
Activities include median removal, landscaping/tree removal, excavation, concrete work, backfilling, striping and street/median restoration.
Median work is anticipated to begin as early as 10 p.m. Monday, March 29, and continue for approximately one week on weekdays.
• Daytime work hours are 7 a.m. to 4 p.m. Crews may mobilize equipment as early as 6 a.m.
• Nighttime work hours are 9 p.m. to 6 a.m.
Motorists should expect delays and use alternate routes if possible. All closures and detours are included in our interactive map (https://i405improvements.kleinfelder.com/), on our closure list and on the project website.
Please be advised that this work may be loud. Dates and times are subject to change due to unforeseen operational factors or inclement weather.
October 15, 2020 Construction Alert: Full southbound (SB) I-405 closure between Seal Beach Boulevard and SR-22 SB is set for 11 p.m. Saturday, October 17, to 7 a.m. Sunday, October 18.
I-405 Detour is:
SB I-405 off-ramp to Seal Beach → SB Seal Beach → Eastbound (EB) Westminster Boulevard → SB I-405 on-ramp
EB SR-22 Detour is:
EB SR-22 off-ramp to Seal Beach → SB Seal Beach → EB Westminster → Northbound (NB) Bolsa Chica Road → EB Garden Grove Boulevard→ EB SR-22 on-ramp
June 15, 2020 Construction Alert: Crews will begin median removal activities on Seal Beach Boulevard between Lampson Avenue and Old Ranch Parkway. This work will require continuous lane reductions on Seal Beach Blvd. for the duration of the work.
The center median will be demolished, removed and reconstructed to allow for the addition of a second left-turn lane from southbound (SB) Seal Beach Blvd. to the northbound (NB) I-405 on-ramp.
Activities include median removal, landscaping/tree removal, excavation, concrete work, backfilling, striping and street/median restoration.
Median work is anticipated to begin as early as 10 p.m. Monday, March 29, and continue for approximately one week on weekdays.
• Daytime work hours are 7 a.m. to 4 p.m. Crews may mobilize equipment as early as 6 a.m.
• Nighttime work hours are 9 p.m. to 6 a.m.
Motorists should expect delays and use alternate routes if possible. All closures and detours are included in our interactive map (https://i405improvements.kleinfelder.com/), on our closure list and on the project website.
Please be advised that this work may be loud. Dates and times are subject to change due to unforeseen operational factors or inclement weather.
May 26, 2020 Construction Alert: Crews will begin pile driving activities to build the foundation of the Magnolia bridge. Approximately 130 piles will be used.
The activity will occur along northbound and southbound I-405 and in the freeway median at Magnolia.
Some activity, such as equipment mobilization and hauling materials, may occur at night.
Beginning as early as Tuesday, May 26, 2020. Daytime schedule 7 a.m. to 4 p.m. and nighttime schedule 10 p.m. to 5 a.m. This activity is anticipated to last approximately one month.
Please be advised that this work may be loud. Dates and times are subject to change due to unforeseen operational factors or inclement weather.