This paper presents the findings of a research project that examined the behaviour of drivers making left turns across the path of opposing vehicles at T-intersections without traffic signals. The objective was to identify factors affecting the decision to accept or reject an available gap. The focus of the paper is on the results, rather than the techniques used. The data base involved five intersections in the Edmonton area. Over 3400 left turning and 13,000 main stream vehicles, and 17 driver characteristics and gap attributes, were observed. The probability of accepting or rejecting a gap was investigated as a binary choice in a logit model. Over 40 different model structures were examined. Gap size, examined. Gap size, driver gender, presence of passengers in the turning vehicle, and queue delay were found to be important factors in decision-making. Probability of accepting a gap was also influenced by the speed and type of the opposing vehicle, queue delay, microscopic flow of opposing traffic and the presence of vehicles behind the turning vehicle. Perhaps the most interesting results were obtained by the analysis of the impact of front delay. While for delay duration shorter than 30 seconds the probability of accepting a gap decreased, it increased after that period of time. (A)
Abstract