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Gold Line Bridge



On the $18.6-million Gold Line Bridge in Arcadia, California, designers not only met the needs of overlapping governmental bodies but created a signature appearance that reflects the area’s heritage. Inspiration for the serpentine superstructure came from the Western Diamondback rattlesnake, while the basket-like columns represent indigenous Native American handicrafts. The bridge is the first artist-designed transit bridge in the state.

The 584-ft, dual-track bridge, which spans the eastbound I-210 Freeway, kicked off a $735-million, 11.5-mile light-rail project from Pasadena to Azusa. The bridge connects the existing Sierra Madre Villa station in Pasadena and the future Arcadia station (the westernmost of six planned stations).

The bridge features three spans of 8' 10"-deep cast-in-place prestressed concrete box girders, with span lengths of 144, 220 and 220 ft, respectively. The cast-in-place concrete deck is 33’ 11” wide to accommodate two light-rail tracks and a center emergency walkway. Cast-in-place pier caps, columns, and drilled shafts also were used.

Designed to be visually arresting, the bridge’s superstructure features a rounded underside, with a serpentine design along its length consisting of cast grooves and hatch-marks visible from the highway it spans. Column tops were constructed to resemble woven baskets connected with a horizontal support and decorated with reed patterns extending upward.

INNOVATIVE APPROACH

The underside features a curved profile with a longitudinal wave pattern mixed with a transverse rib pattern. Creating the serpentine soffit shape required building temporary falsework and using formliners to create the pattern. The cross-hatching detail was accomplished by nailing small pieces of chamfer to the forms. Each formliner was aligned by hand to ensure the proper shape and to align the grooves and hatch marks.

The outrigger column's basket shapes were created with precast concrete modules reinforced with steel. Sixteen reeds per basket were used with the same curvature but with varying lengths from 2 to 10 ft in height. The concrete mixture contained black stone as well as clear, gray, and mirrored glass to create a sparkling effect that responds to atmospheric conditions.

The 60 column basket’s modules doubled as formwork for closure pours of the bent-cap prestressing anchorage. The complex weaving patterns matched those of the adjacent bent caps and the column down below.

Project Details

Location:

Arcadia, CA

Owner:

Metro Gold Line Foothill Extension Construction Authority, Monrovia, CA

Design Engineer:

AECOM, Los Angeles, CA

Design Concept Advisor/Artist:

Andrew Leicester, Minneapolis, MN

CIP Concrete Supplier:

National Ready Mix, Irwindale, CA

Contractor:

Skanska USA Civil West, Riverside, CA

Precast Concrete Supplier:

Moonlight Molds, Gardena, CA

Reinforcing Bar Fabricator:

CMC Rebar, Fontana, CA

Post-Tensioning Contractor:

Dywidag Systems International, Long Beach, CA

Operator:

Los Angeles County Metropolitan Transportation Authority, Los Angeles, CA

Materials:

Concrete with steel reinforcement (92 percent from local and regional sources). 6,500 cubic yards of concrete and 1.3 million pounds of steel rebar.

Total Project Cost:

$18.6 million

Total Project Size:

584 feet (three spans)

Photography:

Courtesy of Metro Gold Line Foothill Extension Construction Authority, Monrovia, CA

Resources

 
  • CRSI Case Study 150 KB pdf
    This case study is a condensed version of an article that appeared in Aspire magazine, used with permission.