A Safety Evaluation Model for Unsignalized T-Intersections Based on Conflict Probability

In order to evaluating the safety of the unsignalized T-intersections in a more objective way,this paper proposes a safety evaluation method after providing a detailed classification of intersections.The probability of traffic con-flicts is used as the evaluation index.In this paper,the average of traffic conflicts and its probability are described using a generalized linear model and Poisson distribution.In the generalized linear model,the average of the traffic conflicts is used as the explained variable while the conflict traffic flow rate as an explanatory variable.The traffic conflict probability of Poisson distribution is estimated based on the estimated average of conflict traffic.A simplified model is developed after the model parameters are calibrated based on the survey data.The effect of the through movements on main-street is sim-plified by an impact factor,which is divided into 4 levels based on the volumes.By analyzing the relationship between the calculated value of traffic conflict probability and the critical value of safety probability threshold,the safety of the unsign-alized T-intersections is evaluated.The feasibility and accuracy of the model is validated through actual cases.The results show that the traffic volumes of the turning movements have a greater effect on the safety than through movements.The study concludes that the volume of turning movements should be more carefully investigated than the volume of the through movements on main-road when using the proposed simplified model.The efficiency can be improved by 25% in average.