METHOD FOR THE DETERMINATION OF TRAFFIC CAPACITY OF CONTROLLED ROAD INTERSECTION

摘要

A method for the determination of traffic capacity of controlled road intersection is based on scanning intersection zone simultaneously with three unidirectional laser beams from the point above its geometric centre by means of conical scanning. The optical axis of one of scanning positions of first beam is selected in such a way that it describes a circle at traffic area of road intersection at stop-line region of all intersection entries, and second scanning position corresponds to laser beam deflection whereby the radius of second concentric circle at traffic area surface is reduced by preset value. The scanning positions are changed with high speed alternately in each scanning period, and second beam is formed in with bias at one-third period by scanning circle and with change of inclinations of optical axes of first and second beams in reference point alternately in each scanning period in such a way that radius of second concentric circle at entry of the first controlled zone is reduced by preset value. Third optical beam of laser scanning is formed with bias relative to the second one at another one-third period by scanning circle, and inclinations angles of optical axes of third beam, just as other beams, are changed in reference point alternately in each scanning period in such a way that radius of second concentric circle at entry of the second controlled zone is reduced by preset value. The distance between entry and exit boundaries of the second controlled zone is selected from condition that it exceeds most probable vehicle queue that can be formed at one of lanes at stop-light. Reflected optical signals are received by photodetectors and transformed into pulse and numerical codes, on the basis of which determined are speed, vehicle type and moving time at entries and exits of both controlled zones, traffic directions by lanes, number of vehicles in the queue in physical and reduced units, value of stopping path of different vehicle types, time of queue advancing in stop-line zone by all lanes during discrete timing periods of one traffic signalization cycle. The presence of vehicles by particular lanes is determines at first controlled zone and at intersection zone at moment of intermediate timing period beginning, and the moment of the termination of the intermediate timing period is formed on the moments when the last vehicle present in the intersection zone starts to cross by its front bumper one of lines of scanning of the first beam by lanes at the exit from the intersection. The duration of basic timing period is determined by moment of termination of longest queue by lanes within given signalization phase, which is determined by the moment of crossing one of scanning lines at stop-line zone by rear bumper of vehicle last in the queue under condition that at this moment all vehicles leave the first controlled zone, and duration of traffic signalization cycle by scanning results is determined as totality of basic and intermediate timing periods of all phases. During each traffic signalization cycle determined are trajectory parameters of traffic flows at intersection entries and at intersection zone, basic and intermediate timing periods and traffic signalization cycle, as well as motor car correlation factors, traffic intensity flows by each lane at intersection entries. Traffic capacity of intersection approaches is determined as totality of traffic intensity flows of particular lanes with account of basic timing period and traffic signalization cycle duration, and traffic capacity of the intersection is determined as total traffic capacity of particular entries.