COMPARATIVE ANALYSIS OF FACTORS AFFECTING TRANSIT BUS CRASHES TO GENERAL TRAFFIC CRASHES

摘要

This paper evaluates how different roadway cross-sectional elements and traffic characteristicsimpacts crashes involving transit buses and general traffic crashes. The contributing level of eachof the elements is compared between the two crash scenarios. One of the elements included inthe study is the impact of bus trips per day which haven’t been covered by many previousstudies. Zero Inflation Negative Binomial (ZINB) and the standard Negative Binomial (NB)models were applied in the analysis. The ZINB method was applied to the transit bus crashesmodeling due to the presence of many roadway segments with zero crash experiences. Asexpected, the model results presented a positive coefficient for the number of bus trips whichmeant that the higher the number of trips per day, the more crashes for that specific roadwaysegment. Other positive coefficient variables in the bus crashes model include the presence ofraised medians, presence of two way left turn lanes (TWLTL), and high posted speed limits.Negative coefficient variables were found to be number of lanes, median width, lane width andshoulder width and the presence of curb and gutter. While most of the variable coefficient signsin ZINB were the same as those in standard NB, their magnitudes and significances varied acrossthese two models. Study findings present safety factors to consider when assigning transit busroutes and scheduling on top of other general traffic safety measures.