The final design for the $18.6 million “iconic” bridge over the eastbound lanes of the I-210 Foothill Freeway that will carry the Gold Line light rail train Gold Line Bridge has been approved by Caltrans and the Construction Authority, according to the Metro Gold Line Foothill Extension Construction Authority.
The “Gateway to the San Gabriel Valley,” featuring is the first component of the 11.5-mile Gold Line Foothill Extension light rail project from Pasadena to Azusa to advance from the design phase to the construction phase. Trains will cross from the median of the freeway across the bridge into Arcadia, over the bridge at Colorado Boulevard that will be replaced and then over a bridge to be built over Santa Anita Avenue before arriving at a station and transit plaza to be built on the northwest corner of First Avenue at Santa Clara Street. The extension line is scheduled to be open in 2015.
“We started this design process with an exciting artist’s concept paying homage to the region’s historic Native American basket-weaving tradition,” said Habib F. Balian, CEO for the Construction Authority. “That vision has moved from concept to design over the last year, and the bridge’s final design has improved through that process.” The bridge being built by design-build contractor Skanska USA has been undergoing design and pre-construction since August 2010. Since the contract was awarded last year, the Construction Authority and Skanska’s primary design subcontractor (AECOM) have been working with Caltrans and Metro to integrate their different design standards into the structural and aesthetics design for the bridge, going through multiple design submittals with increasing level of detail.
The original concept for the bridge design was envisioned by internationally-recognized and award-winning artist Andrew Leicester, selected to be the project’s Design Concept Advisor following a competitive, international search. With two prominent “basket” columns and a curve-shaped underside of the superstructure, Leicester’s design recognizes the region’s original American Indian inhabitants and the important role they played in the development of the San Gabriel Valley.
Leicester continued to play an advisory role as the design for the bridge developed and will supervise construction of design elements in the coming months.
“The bridge is the most visible element of the Foothill Extension project, and we wanted to utilize that prominence to create a true gateway to the San Gabriel Valley,” said Doug Tessitor, Construction Authority board chairman and Glendora mayor. “The details on the bridge are representative of the rich and proud heritage of the region and will become an important marker for future generations as they enter the Valley by train or car.”
In addition to the unique design elements, AECOM is integrating Time Domain Reflectometry (TDR) technology that has never been used before in bridge foundations. This technology can help assess any damage following an earthquake. The reinforcing steel cages that strengthen the bridge’s 110-foot deep, 11-foot diameter major foundations include wiring placed into the structures that will be able to provide electrical feedback when signals are transmitted down the columns to identify any damage. This “smart column” technology will allow engineers to make an initial assessment regarding the integrity of the columns’ structures electronically rather than relying on the traditional method of digging trenches adjacent to areas where engineers suspect damage could be found.
“The engineers had a true challenge in making the design a reality,” said Balian. “Caltrans required a bridge that can withstand a significant earthquake, Metro added that the structure needs to be operational the day after an event, and the Authority wanted to create an attractive gateway to the San Gabriel Valley. Andrew Leicester and the engineering team met all of these challenges to create a bridge design that will become a recognized, iconic feature for the region.”
— By Scott Hettrick