PROJECT OF THE YEAR

REPAIR AND PRESERVATION OF THE HISTORIC RAINBOW BRIDGE

Valley County, Idaho

Submitted by Vector Corrosion Technologies

Because of its historic significance (listed on the National Register of Historic Places) and strong support from the local community, the Rainbow Bridge in Idaho was designated for rehabilitation, rather than replacement. After years of exposure to deicing chemicals corrosion of the reinforcing steel was occurring and beginning to affect the integrity of the structure. The overall scope of the work included concrete patch repairs, replacement of selected items, and rehabilitation of the arches.

Independent consultants for the owner completed a comprehensive corrosion and structural survey. The chloride testing, corrosion potential testing, and a visual and tactile survey indicated that the most severe corrosion in the substructure was near the deck drains and the joints.

The corrosion mitigation strategy utilized two systems to protect different sections of the structure: electrochemical chloride extraction was utilized for the concrete arch substructure and galvanic anodes were used around the perimeter of concrete patch repairs in the areas that did not receive the electrochemical treatment.

The specified corrosion mitigation systems offered the best combination of service life, cost, and maintenance without major impact on the appearance of the historic structure. After the rehabilitation, the structure has been preserved for the enjoyment of future generations.

Owner
Idaho Department of Transportation
Boise, Idaho

Project Engineer/
Designer
CH2M Hill
Boise, Idaho

Repair Contractor
Vector Corrosion Technologies
Wesley Chapel, Florida

General Contractor
Mowat Construction
Desert Hills, Arizona

Material Suppliers/
Manufacturers
Vector Corrosion Technologies
Wesley Chapel, Florida