Evaluation of bridges for improvement in bridge management systems depends on accurate estimates of various user and agency costs associated with both the existing structure and the proposed improvement. The results of a study to estimate the annual number of accidents on a bridge and the average per-accident cost are reported. Accident costs are estimated on both the human capital approach and the willingness-to-pay approach. The accident rate relationship was determined by matching more than 2,000 bridge-related accidents to specific bridges and using various forms of regression to develop a prediction equation as a function of specific bridge characteristics.