Comparative Analysis of Bridge Superstructure Deterioration

This paper presents the results of a study of rates of deterioration of steel and prestressed concrete bridge superstructures. The study involved forming sample groups of bridges that were homogeneous in terms of characteristics, other than superstructure material, which were expected to influence rates of deterioration. Superstructure condition rating was regressed against age and average daily traffic for sample groups of homogeneous steel and prestressed concrete bridges in the nation as a whole, as well as in seven states selected to represent diverse terrains and environments. Results indicated that age is the primary determinant of superstructure deterioration, followed by average daily traffic. Choice of structural material does not significantly affect superstructure deterioration rates. The study also found that deterioration of bridge superstructures takes the form of a convex function over time, with the rate of observed deterioration slowing as a bridge ages.