In the review of accidents involving overtaking, the database showed two facts which prompted further investigations: (1) Over 90% of such accidents in the area considered occurred on locations where the overtaking was not prohibited; and (2) The highest accident rate noticed took place on an almost straight section with good environmental conditions and no intersections, followed by a long section where overtaking was prohibited. A conclusion could be made that the overall adverse traffic and road conditions forced drivers to undertake unsafe maneuvers at the first opportunity. To explore a general relation between the demand for passing and passing opportunities in different traffic and road alignment conditions, a macrosimulation model based on homogeneous Markov chains has been established. Such a model enabled the appraisal of which type of overtaking (free flow or from a platoon) prevails in various circumstances. Some examples of the results (the number of required passings, the relation between the number of free flow and platoon overtaking performed and the needed passing sight distance), obtained for the vehicle fleet characteristics recorded in the given area, are shown in the paper.
Abstract