If widening and improving the busiest highway in the nation with the addition of two new general-purpose traffic lanes and two new tolled express lanes wasn’t enough of a challenge for OC 405 Partners Joint Venture, add in the reconfiguration of 12 interchanges and two major connectors plus 22 bridges! That’s right – 22 new bridges that span, in some stretches, 14 lanes of traffic.

The 405 Improvement Project, featured in the last issue of Innovation Highway, is a $2.08-billion endeavor that 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 features the addition of one continuously reinforced concrete pavement general-purpose 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 the aforementioned 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.

The Orange County Transportation Authority (OCTA), working in conjunction with Caltrans, awarded the project to OC 405 Partners Joint Venture, which is comprised of OHLA USA, Inc. and Astaldi Construction Corporation. 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.

The bridges of the 405 Improvement Project are a significant component of the work, each taking approximately 12 to 24 months to complete, depending upon the scope of work, physical and logistical constraints, and whether or not the bridge is completely closed during construction. After demolition of the old structure, the bridge abutments are constructed, which entails installing temporary shoring and excavation, pile driving, and building the steel and concrete abutments. Center columns are then constructed, and falsework, the temporary steel beam and timber structure to support the new bridge is installed. Once the falsework is in place, the superstructure, deck, approaches, sidewalks, curbs and gutters, and electrical systems are built.

The 22 improved structures feature increased widths and heights, and in some cases, the bridges will be almost doubled in width. Improvements to the bridges include new sidewalks, new bike lanes, and attractive aesthetic details.

Detail photos courtesy of the Orange County Transportation Authority

Starting on the north end of the 405 Improvement Project, here are the bridges that are being improved and their current construction status as of December 1st:

 

Bolsa Chica Road Bridge – Phase One Complete, Open to Traffic

Springdale Street Bridge – Under Construction, Closed to Traffic

Westminster Boulevard Bridge – Phase One Complete, Open to Traffic

Edwards Street Bridge – Complete, New Bridge Open to Traffic – Photo courtesy of the Orange County Transportation Authority

 

Goldenwest Street Bridge – Phase One Complete, Open to Traffic – Photos courtesy of the Orange County Transportation Authority

Bolsa Avenue Bridge – Phase One Complete, Open to Traffic

McFadden Avenue Bridge – Complete, New Bridge Open to Traffic – Photo courtesy of the Orange County Register

Beach Boulevard Bridge – Open to Traffic during Construction

Edinger Avenue Bridge – Complete, New Bridge Open to Traffic

Newland Street Bridge – Under Construction, Closed to Traffic

Heil Avenue Pedestrian Bridge – Under Construction through December 2021, Closed to Traffic – Photo courtesy of the Orange County Transportation Authority

 

Magnolia Street Bridge – Complete, New Bridge Open to Traffic – Photo courtesy of the Orange County Transportation Authority

Warner Avenue Bridge – Under Construction, Closed to Traffic

Bushard Street Bridge – Complete, New Bridge Open to Traffic – Photos courtesy of the Orange County Register

Slater Avenue Bridge – Complete, New Bridge Open to Traffic

Brookhurst Street Bridge – Phase One Complete in January 2022, Open to Traffic

Talbert Avenue Bridge – Complete, New Bridge Open to Traffic

Ward Street Bridge – Under Construction, Closed to Traffic

Santa Ana River/Euclid Street – Open to Traffic during Construction

Harbor Boulevard Bridge – Open to Traffic during Construction

Fairview Road Bridge – Phase One Complete, Open to Traffic

NEW I-405/SR-73 Express Lanes Connector – Under Construction

Crews are working on the foundation of the southbound I-405/SR-73 HOV Connector bridge. The foundation consists of eight cast-in-drilled-hole (CIDH) and 35 steel-pipe piles. The CIDH activity includes installing large-diameter casings approximately 200 feet into the ground. The steel-pipe piles will be driven into the soil until they reach a hard layer of earth beneath the foundation of the structure.