Estimating the Accuracy of Opposing Left-Turn Potential Conflict Model Via Programming in MATLAB

According to accident statistics for selected intersections in Tehran, Iran, head-side accident occurring at intersections assign the major part of the reported accidents in compare to the other types of reported accidents. Analyzing the accident reports, indicate that the opposing left-turn accidents conclude the significant part of head-side accidents. Hence, developing a method for analyzing and estimating opposing-left-turn accidents can be used as a surrogate safety measure in evaluating relative safety level of signalized intersections. In this regard, historical crash data have been used widely as a direct measure of safety at intersections and other locations. However, attempts to estimate the relative safety of a highway facility are usually hindered by the unreliability of crash records and the long period to achieve adequate sample sizes, furthermore non-accessible accident database in Iran, emphasis the need for a surrogate safety measure which can be used to overcome these problems. Analyzing the predetermined methods indicate that traffic conflict technique´s ability in predicting the number of accidents and potential risk of road network (especially intersections) in one side and also limited field observation time and low costs on the other side, determined this method as an effective surrogate safety method. Consequently, the proposed methodology was determined based on Traffic Conflict Technique concepts and designed to be compatible with HCM2000. By inspiration of Dr Lin Zhang and Panos D. Prevedouros predetermined model of estimating opposing left-turn conflicts probability [2], model improvement and model verification for 15 selected intersections in Tehran is performed. Besides, in order to simplify the calculation process of opposing left-turn conflict probability, programming in MATLAB is used.