The structural behavior of these decks under vehicle live loads and their long-term durability under environmental and vehicular demands will be studied. The performance of the decks will be compared and contrasted with due consideration of the known and projected costs for each type of deck. The project results will include:• a description of the load carrying mechanisms observed for each deck (load path and load magnitudes),• a description of the distress sustained by each deck over the duration of the project and the associated causes of this distress (e.g., live load demands, thermal expansion and contraction, etc.),• an estimate of the effect of this distress on the longevity of each deck,• an analysis of the life cycle costs of each deck (although this analysis will be based on only a few years of performance data), and•benchmark data on as-built deck conditions and early deterioration that can be used to evaluate performance well into the future.