| The main goal of this study is to characterize structurally deficient bridges and the rates at which they deteriorate. The scope of the study is limited to steel and pre-stressed bridges in the state of Oklahoma. The analysis utilized data from the National Bridge Inventory (NBI) for the years 1992--2010. The bridges were categorized as structurally deficient, functionally obsolete, or not deficient. The primary objectives of the study were to identify annual trends in deficient bridges, estimate deterioration rates of substructure, superstructure, deck, and sufficiency ratings, and compare the trends and deterioration rates for steel and pre-stressed concrete bridges. The deterioration rates for each rating were determined by simple linear regression of rating versus age with the slope component of the regression line being defined as the deterioration rate. Key findings include the number of steel deficient bridges increased from 1992 to 2003 but decreased from 2003 to 2010 whereas the number of concrete bridges increased from 1992 to 2010; substructure, superstructure, and deck ratings for pre-stressed concrete bridges had higher deterioration rates than steel bridges; and the deterioration rate of the overall sufficiency rating for both steel and pre-stressed concrete bridges were nearly the same. |
