Examining Crossing Conflicts by Vehicle Type at Unsignalized T-Intersections Using Accepted Gaps: A Perspective from Emerging Countries

Abstract

The present study focuses on examining the potential of accepted gaps to assess traffic safety at unsignalized T-intersections by estimating the likelihood of a crash. Four unsignalized T-intersections with varying geometry from four different cities in India were selected. Postencroachment time (PET), a surrogate safety measure, was included in the present study to validate the results obtained through the accepted gap. The critical gap was devised as a potential parameter to evaluate traffic safety based on accepted gaps. Various probability distributions were checked for defining accepted gap and PET datasets. Generalized extreme value (GEV) was found to be the best-fitted distribution defining both: accepted gap and PET datasets. Thereafter, GEV distribution was used to estimate the likelihood of crash using accepted gap and PET datasets. The statistical check showed no significant difference in the crash probability obtained using the accepted gap and PET. Thus, the study was further extended, and risk characterization was performed using accepted gap data. The risk is characterized into different levels using the K-means clustering technique. The results attained were validated with 3 years’ crash data obtained from Surat police authorities. The developed risk thresholds provided a close approximation with the crash data. Thus, it can be concluded that accepted gaps can be considered as a potential surrogate safety measure for analyzing the risk and severity of crossing conflicts at unsignalized intersections.