VEHICLE-ARRIVAL CHARACTERISTICS AT URBAN UNCONTROLLED INTERSECTIONS

Vehicle-arrival characteristics are an important input for evaluating the performance measures at urban uncontrolled intersections. In the p resent study an attempt is made to identify suitable probability distr ibution models for vehicle arrivals at uncontrolled intersections unde r mixed traffic conditions. Data consisting of traffic volume,composit ion, and speeds of various types of approaching vehicles were collecte d at number of intersections and analyzed using various statistical te chniques. A speed variation factor is introduced, and a linear relatio nship between speed variation factor and traffic volume is observed. A multivariate distribution framework is suggested for vehicle arrivals at uncontrolled intersections under mixed traffic conditions. A Poiss on distribution gives a close fit to vehicle arrivals, where the traff ic volumes are less than 500 vehicles/hour/lane only. The multivariate distribution concept can be used for higher traffic volumes under mix ed traffic conditions. Issues related to the applicability of the prop osed probability models are briefly discussed.