Coating systems for corrosion mitigation of structural steel and reinforcing steel in marine bridge applications have been widely used. However, novel materials continue to become available and interest lies in identifying improved material performance for marine bridge applications. Research in progress considered Thermal Diffusion Galvanizing (TDG) with various industry-recommended topcoats. Test parameters included evaluating local coating defects such as abrasion, environmental conditions, and chloride contamination. Physical parameters such as coating thickness and adhesion were also assessed to elucidate corrosion deterioration mechanisms. Immersion in neutral pH water provided an aggressive environment analogous to coatings on structural steel exposed to wet environments (e.g. pooled runoff water). Simulated concrete pore solution (SPS), pH 13.3, was used to identify performance of coated steel in reinforced concrete applications. Accelerated corrosion tests including salt-fog exposures and outdoor exposures were made to identify the possibility for localized corrosion. Preliminary testing of TDG samples in outdoor and salt-fog exposure, and immersion in solution showed varying topcoat durability and subsequent varying performance of TDG. No enhanced corrosion at defect sites was apparent during the length of testing for any test conditions; however results did indicate active corrosion of the zinc and possible early TDG degradation.