Interstate 605 is a major thoroughfare for moving people, goods, and service throughout the Los Angeles region. But this 28-mile corridor has not seen any major system-wide improvements for nearly five decades since its construction in 1971.

Over the past eight years, L.A. Metro has been planning and designing improvements for I-605, working with HDR, Caltrans, the Gateway Cities Council of Governments, and the San Gabriel Valley Council of Governments to create a project that will improve the safety, mobility, and connectivity throughout the region.

During an overnight closure, the C.A. Rasmussen and Vanguard Construction JV crew sawcuts slabs targeted for replacement in Segment 1.

Spanning close to 200 lane miles of freeway, the “Super 605 Freeway Enhancements Project” covers the entirety of the freeway, beginning in Duarte in the San Gabriel Valley and extending all the way down to Los Alamitos near Long Beach. Funding for the six-plus-year, $298.4-million project comes from the federal Infrastructure Investment and Jobs Act (IIJA), $273.3 million; S.B. 1, $23.3 million; and the State Highway Operation and Protection Program (SHOPP), $1.8 million.

After demolition and removal of the old concrete, plus the excavation of three feet of the existing subgrade soil as per the pavement design engineer’s request, the excavated site is filled with new structural backfill material before placing the new structural approach slab.

Construction and rehab efforts of the concrete pavement roadway will extend its lifetime, reduce costly repairs, provide a smoother ride for motorists, and create a safer environment for Caltrans workers by reducing the frequency and duration of pavement maintenance.

The project is divided into three segments. Segment 1 starts at the southern end of I-605 at Katella Avenue in Los Alamitos/Long Beach and proceeds to Telegraph Road in Santa Fe Springs. Segment 2 begins at the I-10 intersection and goes all the way to the terminus of I-605 north of I-210. And Segment 3 covers the remaining stretch of I-605 between Telegraph Road in Santa Fe Springs north to the intersection of I-10.

A new batch of concrete is tested before it’s poured to create a new replacement section.

Segment 1, covering 96 lane miles of pavement, was awarded to the joint venture of C.A. Rasmussen and Vanguard Construction and is valued at $72.8 million, with $59 million allotted for construction. Targeted completion for Segment 1 is early 2028.

The crew finishes the new concrete replacement slab during one of the 55-hour closures.

Work is underway on the removal and replacement of distressed pavement and concrete slabs. Additional scope includes the upgrading of curb ramps, and applying treatment to ramps and connectors to enhance skid resistance. A series of eighteen 55-hour closures will be implemented to execute the concrete slab replacements.

Pictured during a partnering session are key members of the Caltrans / C.A. Rasmussen / Vanguard Team. Front row, from the left, are: Tom Sharon, Danny Vega, Emre Erzen, George Malacalza, Ryan Luong, Ojas Sheth, and Tien Chu. In the back row, from the left, Jose Cruz, Miguel Rodriguez, Kelvin Cheng, Gary Rivers, Nikhil Lakkamraju, James Salcedo, Bryan Nguyen, and Martin Oregel. Photo by Clare Singleton, Partnering Facilitator, StreamLine.

C.A. Rasmussen’s subcontractor, RV Concrete, proposed an innovative solution to raise the elevation and profiles of the newly installed approach slabs. The innovation will significantly improve the roadway conditions of the final pavement.

Segment 2 is valued at $24.5 million, with $19.4 million toward construction. Peterson-Chase General Engineering Construction is the contractor on this segment. Work has not yet commenced on Segment 2 due to inclement weather. When it does clear up, the scope of work will include the rehabilitation of the pavement and concrete slabs, upgrades at on- and off-ramps, eight new vehicle maintenance pullouts, more than 12,000 linear feet of guardrail, and the replacement of 27 overhead sign structures. It’s projected that 1,450 cubic yards of Rapid Strength Concrete will go into replacing the individual damaged concrete slabs between I-10 and I-205 in both northbound and southbound directions. Peterson-Chase will also be paving 37,500 square feet of six new ramp termini with an additional 1,400 cubic yards of Rapid Strength Concrete. Anticipated completion of Segment 2 is the fall of 2026.

The lion’s share of the funding, $201.1 million, is allocated to Segment 3, with construction receiving $181.6 million. Along with rehabilitating the pavement and concrete slabs, construction will include 93 lane miles of new concrete pavement. Additionally, more than 16,000 linear feet of guardrail will be upgraded, 16 overhead sign structures will be replaced, and 53 acres of landscaping and stormwater improvements will be performed. The contract for Segment 3 is expected to be awarded in June of this year. Targeted completion for Segment 3 is early 2030.

A big thanks and a tip of the hard hat to District 7 P.I.O. Marc Bishoff for all of his contributions to this story, including the photos; to C.A. Rasmussen Project Manager Emre Erzen, P.E. for his contributions; and to Peterson-Chase Project Manager Kolbe O’Donnell.