Serious Conflicts: A Safety Performance Measure at Signalized Intersections

There is a challenge to identify potential sites for safety improvement in case of shortage in crash data. This study explores alternative method based on traffic conflicts as a surrogate safety measure instead of crash data. The study demonstrates two family major safety assessment streams; three of crash-based methods proposed by Highway Safety Manual and two conflict-based methods. For crash-based methods, Empirical Bayes (EB-method), crash frequency and crash rate measures are used. Conflicts frequency and conflicts rate for two surrogate safety indicators are used in the conflict-based methods, in this study, EB-method is used as a benchmark for comparison. The safety evaluation was performed separately for 9 signalized intersections, the safety measures are estimated and compared through Pearson correlation analysis while hazard location identification results through the use of rank-based mean absolute. Results showed that the serious conflicts frequency as a conflict-based method had a high correlation and a coefficient of 0.986 with the EB-method in the resulting outcomes and performed better than crash frequency method in identifying hazard location when compared with EB-method. Therefore, the serious conflicts frequency can serve as a viable option for safety performance evaluation and hazard locations identification, especially when sufficient crash data are not obtainable.