Long-lasting coating system minimizes future maintenance on pedestrian bridge

July 12, 2021
The two 42-ft-high steel arches along the Iron Horse Trail in Contra Costa County, California, are protected by a high-performance polyurethane coating system.
The two 42-ft-high steel arches along the Iron Horse Trail in Contra Costa County, California, are protected by a high-performance polyurethane coating system.

With its curving arches and long-lasting polyurethane coating system, the 800-ft-long pedestrian and bicycle overcrossing along the Iron Horse Trail in Contra Costa County, California, is a footbridge with flair.

Named the Robert I. Schroder pedestrian bridge, the innovative bridge design was completed in October 2010. 

“Keeping to a tight schedule was critical,” said Todd Anderson, project manager for Jeffco Painting and Coating in Vallejo, California. “The city wanted disruption to the traffic flow to be kept at an absolute minimum.”

Located in the major transportation and commercial hub of Pleasant Hill, the visually striking bridge is supported by widely spaced cables suspended from two 42-ft-high arches constructed of steel pipes that were bolted together. 

All structural steel was primed by the fabricator with Series 90E-92 Tneme-Zinc, an ethyl silicate inorganic, zinc-rich primer with tenacious bonding and corrosion resistance, followed by an intermediate coat of Series 66 Hi-Build Epoxoline, a polyamide epoxy. The arches received a finish coat of Series 1077 Enduralume, an aliphatic acrylic polyurethane containing a sparkle aluminum pigment that creates a metallic finish.

For spot repairs and iron bolts, the field applicator prepared the substrate in accordance with SSPC-SP6/NACE No. 3 Commercial Blast Cleaning. Brushes and rollers were used to apply Series V69F Hi-Build Epoxoline II, an advanced generation polyamidoamine epoxy, which conforms to air pollution regulations limiting volatile organic compounds (VOCs). 

For field touch-up where abrasive blasting was not feasible, the applicator prepared the surface in accordance with SSPC-SP3 Power Tool Cleaning and SSPC-SP1 Solvent Cleaning. These areas were then primed with Series 135 Chembuild, a high-build polyamidoamine epoxy for marginally prepared rusty steel and tightly adhering old coatings.

All steel surfaces, except for the arches, received a full finish coat of Series 740 UVX, an advanced technology polyurethane that offers less than 100 grams/liter VOC content, superior color and gloss retention, and a hard, durable film that stands up to abrasion, exterior weathering, and ultraviolet (UV) light. 

“We recoated the bridge with Series 740 to compliment the silver and dark aluminum Enduralume colors,” noted Anderson. “The finish coat sprays nicely and can make any structure look great.”

The $6.8 million Robert I. Schroder pedestrian bridge, named for a former Contra Costa County supervisor and community activist, is part of a plan to improve access to the Pleasant Hill Bay Area Rapid Transit (BART) Station, while making the Bay Area’s Iron Horse Trail safer. 

After more than 10 years, the topcoat continues to perform beyond expectations and the bridge itself continues to be a centerpiece of the community and the Iron Horse Trail.

The Robert I. Schroder bridge in Pleasant Hill, California, was originally coated in 2010 and its coating system continues to protect the steel from corrosion and UV light degradation today.
The Robert I. Schroder bridge in Pleasant Hill, California, was originally coated in 2010 and its coating system continues to protect the steel from corrosion and UV light degradation today.

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Editor's Note: Scranton Gillette Communications and the SGC Infrastructure Group are not liable for the accuracy, efficacy and validity of the claims made in this piece. The views expressed in this content do not reflect the position of the Roads & Bridges' Editorial Team.

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