Flatiron Construction Creates New $77M Interchange for San Juan Capistrano
A long-awaited renovation to the highway interchange at Interstate 5 and California State Route 74 (Ortega Highway) was recently completed at San Juan Capistrano. The $77.2 million project was a joint effort of the California Department of Transportation (Caltrans), the Orange County Transportation Authority (OCTA) and the City of San Juan Capistrano. Flatiron Construction, headquartered in Broomfield, Colorado, was the contractor.
The SR 74 originates at San Juan Capistrano and takes traffic east. Following the path of a Native American trail. It was built in the early 1930s and is named the Ortega Highway after the Spanish explore JosÃ© Francisco Ortega who led an expedition exploring the area in 1769. The Los Rios Historic District just west of the highway is the oldest continuously occupied neighborhood in California, with buildings dating back to 1794.
Looking for Solutions
Beginning about 15 years ago, local authorities began looking for ways to provide congestion relief and improve local and regional traffic, improve traffic safety at the interchange and approaches, and to provide capacity for future local development.
Engineering and environmental studies were conducted in the mid-2000s and the City Council approved the selected alternative plan in 2009.
To meet their goals, project managers determined a scope of work that involved five elements:
· To replace the existing interchange
· To construct a new, expanded bridge
· To widen the existing on and off-rams
· To construct a new northbound I-5 loop on-ramp from east-bound traffic on the Ortega Highway
· To realign Ortega Highway to the west of the interchange to curve into Del Obispo Street and eliminate the need for two intersections
Ground was broken on the project in February 2013, with an initial timeline calling for completion by spring of 2015. Some adverse weather and the challenges of staging the project to accommodate city concerns stretched completion by a few months.
According to OCTA, the major challenge was to keep traffic moving throughout the site during construction. To meet that constraint, the project was constructed in 11 stages, which allowed traffic lanes to remain open in each direction most of the time.
"The most significant issue arose with the realignment of Ortega Highway to curve into Del Obispo Street," said OCTA Spokesman Eric Carpenter. "That required closing off direct access to the city's downtown for motorists and pedestrians. We handled that through advance outreach to businesses and residents that continued weekly throughout the closure."
The entire project consumed approximately 120,000 man-hours. Roadway construction crews had between 10 and 25 members. Specialty crews for construction of bridges and retaining walls varied between 10 and 30 members depending on the work load. The crew involved in placing fill comprised about 10 to 15 members.
Heavy equipment used on the project included Pile driving equipment, ac pavers, front-end loaders, Caterpillar dozers, heavy dump trucks, excavators, vibratory compactors, slipform pavers, rollers, and backhoe loaders.
The project made extensive use of time and labor-saving materials. Special materials included: Geofoam, lightweight concrete, geo-composite drains, architectural treatment panels, street pavers, geo-membranes and continuously reinforced cement concrete (rapid setting).
Construction of the MSE retaining wall at the northbound off-ramp consisted of precast concrete panels, welded mesh, structure backfill and use of lightweight fill (cellular concrete) for embankment construction. Expanded polystyrene (EPS) Geofoam blocks and gasoline resistant Geomembrane (GRC) were used for lightweight fill. The roadway was constructed with continuously reinforced concrete pavement (rapid strength concrete) on top of Geofoam lightweight fills. The project used 18,000 cubic yards of EPS Geofoam blocks for fill.
Plenty of traditional materials were also used, including: 35,000 tons of asphalt, 10,000 feet of steel piling, 6,700 cubic yards of concrete in the bridge and eleven retaining walls, 4,700 cubic yards of lightweight concrete and 1.1 million pounds of rebar.
To provide a figurative bridge back to the historic nature of the area and the Spanish colonial style of architecture, the project used colored concrete on the new bridge and features textured, hand-painted retaining walls.
Funding the Project
The $77.2 million project was funded with $42.7 million from the State Transportation Improvement Program (derived from gas tax), with an additional $5.6 million provided by Measure M, Orange County's half-cent sales tax for transportation improvements, and $1.8 million from the city of San Juan Capistrano. The remaining chunk of funding, $26.9 million, came from Proposition 1B, a 2006 voter-approved bond. Caltrans reports that to date, more than $18 billion in Proposition 1B funds have been put to work statewide for transportation purposes.
Money well spent, according to transportation and local officials.
"This project will be good for commuters and good for the economy, as the I-5/Ortega Highway is a key route for the movement of people, goods and services throughout California," said Caltrans Director Malcolm Dougherty at the opening ceremony. "These improvements will provide much needed congestion relief, improving not only local traffic flow but easing regional commutes as well."
OCTA Chairman Jeff Lalloway (who is also Mayor Pro Tem of Irvine) said, "This is a project in line with our mission at OCTS to help keep Orange County moving. It helps relieve a notorious choke point for local drivers and regional commuters."