These viaducts are located in downtown Ketchikan and are part of the main north-south arterial in the city. Tinnea & Associates was the prime contractor for a multi-disciplined inspection team that included two structural engineering firms, an underwater inspection company, a ground penetrating radar consultant and the former City Engineer as subcontractors. The fact that all the work was over water that can see daily tide swings of 20 feet complicated access and required careful attention for both access and safety. The findings of this work were compiled in several bound volumes, CD-ROM, and videotape.

Based upon the findings of that inspection, Tinnea & Associates completed a restoration design and prepared the construction plans and specifications. Corrosion control is achieved by using galvanic cathodic protection systems. The deck and girders are protected by thermally sprayed zinc anodes. The pile caps, upper elevations of the piles and retaining wall are protected by jacket systems with integral zinc anodes. The lower elevations of the piling are protected by bulk galvanic anodes.

Kerri Howell, P.E. made a presentation on the bridge inspection and design at the NACE International Corrosion 2000 Conference. Jack Tinnea made a follow-up presentation on the construction phase at the 2001 meeting of the US Transportation Research Board. The project was also featured in the February 19, 2001 issue of Engineering News-Record.