Evaluation of the Consistency of Bridge Inspection Ratings in New York State

Abstract

Previous studies by the Federal Highway Administration (FHWA) have shown significant variability in the rating of bridge elements through visual inspection. In this study, a detailed evaluation of the consistency of inspection ratings of four representative bridges in New York State has been conducted, using inspection data reported by 21 inspection teams employed by the New York State Department of Transportation (NYSDOT). The bridge condition rating scale of NYSDOT ranges from 7 to 1, with 7 being new and 1 being in a failed condition. In addition, the NYSDOT assigns ratings 8 and 9 to cases “not applicable” and “condition and/or existence unknown,” respectively. In general, consistency is defined as “conformity with practices and procedures.” In this study, consistency of inspection of elements has been quantified as a percentage of inspectors that rated the bridge element within ±1 of the median rating for elements with ratings 7 to 1, or as a percentage of inspectors who have assigned a rating of 8 or 9 to elements expected to be rated 8 or 9. Based on the evaluation of the consistency of elements of the four bridges in the study, the results show that 96% of the elements have a consistency of at least 90%. Only seven elements have been identified to have a consistency of less than 90%. For elements whose rating was supposed to be 8, approximately 97% of the elements had a consistency of at least 90%, whereas, for elements whose rating was supposed to be 9, 91% of the elements were inspected with a consistency of at least 95%. Overall team consistency based on inspection of all elements was approximately 98%. The results imply that the NYSDOT bridge inspection and training programs are effective, as evidenced by the reporting of consistent bridge ratings by multiple inspection teams.