Anyone who has ever driven the 405 through Orange County is well aware of the traffic, the congestion, and the condition of the roadway, bridges, and ramps. The I-405 corridor is recognized as the busiest road in the United States, with 370,000 vehicles traveling it daily.

The 405, looking south, from Springdale Street in Westminster. Photo courtesy of Jeff Gritchen, Orange County Register.

The Orange County Transportation Authority (OCTA) and Caltrans are also well aware of the traffic and road conditions, and for more than a decade have been carefully planning the 405 Improvement Project, which is currently midway to completion, being built by OC 405 Partners Joint Venture. The project entails the widening the San Diego Freeway (I-405) between the SR-73 freeway in Costa Mesa and I-605 near the L.A. County line, a stretch of 16 miles.

The project, which stretches through Orange County from Irvine on the south to Long Beach on the north, will extend the life expectancy of pavement, improve safety and efficiency for all modes of travelers, enhance traffic operation, and manage congestion. An added bonus will be the ability to collect, analyze, and utilize data for systems performance along the I-405 corridor.

The project features the addition of one regular lane in each direction between Euclid Street and I-605, reconfiguration of 12 interchanges and two major connectors, new concrete entrance and exit ramps, and the reconstruction of 22 bridges. In addition, the project is adding the 405 Express Lanes, which incorporate the existing carpool lanes and add a new lane in each direction between SR-73 and I-605. When completed, I-405 will have a total of two new toll lanes with five to seven general purpose lanes.

The total project cost is estimated at $2.08 billion, funded through a combination of local, state, and federal funds, with the 405 Express Lanes portion of the project to be paid for by those choosing to use the express lanes. Here’s the breakdown on the funding – $1.316 billion from OC Go, $90 million from Caltrans, $46 million from Federal funding, and $629 million from a Federal Transportation Infrastructure Finance and Innovation Act (TIFIA) loan secured by the 405 Express Lanes future revenue.

Design-Build Was a Wise Choice

The 405 Improvement Project was programmed to be design-build to provide OC 405 Partners Joint Venture with the ability to innovate throughout the process and improve the efficiency of the operation.

Construction photo courtesy of Frank Stevenson, Pavement Manager at OC 405 Partners Joint Venture.

The design-build method creates a partnership between the client, designer and the contractor, which reduces the risk of design errors and the need for redesigns. Design-build accelerates project delivery, shortens the project duration, and gives the contractor flexibility to respond to changing conditions such as materials and workforce availability, weather, and other extenuating circumstances.

OC 405 Partners is the joint venture of contractors OHLA USA, Inc. and Astaldi Construction Corporation. OHLA has delivered more than 3,700 miles of roadways that safely and efficiently connect communities and key economic centers around the world. OHLA USA has constructed 103 design-build projects and 14 toll road projects that total more than 620 miles. Astaldi is an international construction group that builds technologically complex infrastructure and transportation projects, with 90 successful design-build completions and more than 9,300 miles of highway and roadway projects.

The design team is led by Pacific Infrastructure 405 Designers, a joint venture of California-based Moffat & Nichol with H.W. Lochner, Inc. and Arup North America Ltd. Together, the JV design group avails the talent of a transportation-focused workforce of more than 3,000 professionals, with 76 design-build project completions and a thorough understanding of the local infrastructure environment through ongoing projects and relationships with Caltrans, OCTA, and local agencies.

Construction photo courtesy of Frank Stevenson, Pavement Manager at OC 405 Partners Joint Venture.

Since being awarded the project in 2017, the OC 405 Joint Venture Team has worked to assemble top-notch crews to build the new roadway. For the paving operations, construction crews are being led by Frank Stevenson, Pavement Manager at OC 405 Partners Joint Venture.

“The OC 405 crews are doing an outstanding job performing the work seamlessly as a team,” Stevenson stated, “working with our great subs, all in conjunction with the designers and engineers.

“Caltrans has been a great partner throughout the project,” Stevenson continued, “supporting and encouraging the sustainable aspects of the project, along with establishing a close working relationship with the OCTA, and listening to the OC 405 team’s suggestions, such as our specific shutdown recommendations, which has allowed for more efficient and faster work, minimizing the impact on the public.”

Ramping Up with Concrete Pavement

Early in the design process, the change was made to build the ramps with concrete instead of asphalt. This is unique as many design engineers don’t think concrete can be used to construct ramps. Common misbeliefs are that concrete takes too long, costs too much, can’t be used on steep grades and super-elevations, and the ride quality will be poor.

The OC 405 Joint Venture teams are proving all of those assumptions wrong and building concrete ramps of amazing quality. The crews are utilizing 3D stringless paving on the ramps and it has had a huge, positive impact, reducing the amount of grinding required by 30%, and delivering extremely smooth pavement surfaces. The 3D technology has also enabled the crews to optimize the ramp paving on the fly and finish the ramps with much greater efficiency.

Ramp construction photo courtesy of Frank Stevenson, Pavement Manager at OC 405 Partners Joint Venture.

Paving concrete on steep slopes and super-elevations can be challenging but with a few adjustments to the paving process, excellent results are achievable. In addition to using 3D paving, the paving team stiffened up the fresh concrete a bit and slowed down the paver. This allowed for the placement of all of the loop ramps with the new CT max super-elevation for cross slope of 12%.

The teams are also demolishing the myth that concrete ramps take too long to build. The projected time frame for the demolition and removal of each old ramp, construction of the new drainage system, building of the structural support, and pouring and curing of the concrete was established at 32 to 42 days. The overwhelming majority of ramps have successfully completed within that window, and in one case, came in at a record 30 days.

Caltrans recently made a change to the Standard Specification that helped the OC 405 Joint Venture Team pick up three to five days on each of their ramp construction schedules. The requirement to wait 10 days before allowing traffic on new concrete pavement was eliminated by Caltrans. Now, contractors only need to meet concrete strength requirement before opening pavement to traffic.

Ramp construction photo courtesy of Frank Stevenson, Pavement Manager at OC 405 Partners Joint Venture.

For these new ramps, the end result is truly monumental. In the short construction windows allocated for this specific work, the OC 405 Joint Venture Team is delivering smooth and durable concrete ramps that are designed for 40 years of life without the need for any significant maintenance.

The concrete in the ramps account for 133,000 cubic yards of Jointed Plain Concrete Pavement (JPCP) out of the total 288,000 cubic yards of concrete in the project. The mainline roadways will be comprised of 155,000 cubic yards of Continuously Reinforced Concrete Pavement (CRCP).

288,000 Cubic Yards of Sustainable, Long-Life Concrete

The decision to construct the ramps with concrete positively affects the overall sustainability and life-cycle costs of this massive project, as concrete, over the long run, is a much more sustainable pavement material. These same benefits are being experienced with the project’s CRCP concrete pavement – lifespans extending well beyond 40 years without the need for patching or extensive reoccurring maintenance.

The OC 405 Joint Venture Team is taking additional steps to further the sustainability of the project. None of the demolished materials are going into landfills. The team is recycling 100% of the old road sections, bridges, and masonry walls, crushing and screening the materials onsite, then using it as base under the CRCP on the mainline roadway. By having the crushing facility onsite, the old materials don’t need to be transported to an offsite crusher, further minimizing fossil fuel use.

In the next issue of Innovation Highway, we’ll look at Part Two of the I-405 Improvement Project story, focusing on the 24 new bridges, the I-405-SR-73 Express Lanes Connector, the SR-22/I-405/I-605 Express Lanes Connectors, and additional innovative aspects of the project.