Delphi Study on Bridge Condition Rating and Effects of Improvements

Abstract

As part of an effort to develop guidelines for appraising bridge improvement needs, a Delphi study was conducted to seek opinions from bridge inspectors and engineers in the Indiana Department of Transportation (INDOT). The specific objectives of the study were to: (1) Establish relationships between subjective bridge condition ratings and the FHWA's numeric ratings; (2) assess relationships between the subjective rating and the severity and extent of distresses; (3) find relationships between the numeric condition rating and the expected remaining service life of bridges; and (4) estimate the effect of improvements upon the numeric condition rating and expected remaining service life of bridge components. The perception of bridge condition and the interpretation of FHWA's numeric condition rating varied among the bridge inspectors. The Delphi rounds helped to evaluate the amount of variation and subsequently to decrease it. As for the remaining service life of bridges, results from the Delphi analysis and the statistical analysis showed similarities.