Assessing the impact of reaction time on the crossing and merging conflicts and identifying suitable reaction time to detect the critical conflict

Due to the increased vehicular traffic in developing countries, safety in mixed traffic conditions has become a concern. When critical speed was used with surrogate safety measures to identify critical conflicts, studies assumed some driver reaction time without any analysis. This study aims to assess the impact of different reaction times on the Percentage of Critical Conflicts (PCC) and identify the suitable reaction time for critical conflict identification. Post Encroachment Time was used in this study to assess the safety of crossing and merging traffic at unsignalized T-intersections. It was observed that an increase of 1 s reaction time increases 26.92% of PCC. PET extremes of different reaction times were modelled using Generalized Extreme Value distribution. The 1-second reaction time was found suitable as the estimated crash frequencies were similar to the actual field crashes. This approach could also be employed in the homogenous traffic conditions for critical conflict identification.