The effects of queuing detector locations

摘要

A metering roundabout where traffic is controlled by signals whose phase times are influenced by queue detector occupancy may be the solution to reduce queue lengths when there is unbalanced traffic flows at roundabouts. In the past decades, a number of studies have attempted to evaluate the effectiveness of metering roundabout, especially on the dominant approach. Little studies, however, have been directed on how the distance of the queue detector from the stop line affects signal phase time durations, further, the queuing lengths. This research, therefore, seeks to develop a queue length estimation model using parameters such as arrival volumes, conflicting volumes, detector distance and phase time to investigate the relationship of signal setting, detector location and queuing formulations. In order to conduct credible model validations, model output data was compared against the observed data collected using drones. Also, some additional statistical tests were performed for the data. The results from the analyses demonstrated that the queue detector distance can affect the phase time durations and the vehicle queuing lengths on each approach as well as the queuing lengths for the entire roundabout. This study showed that, based on the study for the Old Belair Road roundabout in Adelaide, South Australia, the entire queue length will be minimized when the detector relocated at 150 meters from the roundabout stop line, giving longer phase green times and resulting in decreased intersection queuing lengths.