Operational optimization at signalized metering roundabouts using cuckoo search/local search algorithm

Abstract

A metering roundabout where traffic is controlled by traffic lights with phase times influenced by queue detector occupancy might be the solution to enhance performance when there are unbalanced traffic flows at roundabouts. There have, however, been minimal studies on how the distance of the queue detector from the stop line affects signal phase time durations and the queuing lengths. This research, therefore, seeks to develop a Cuckoo Search/Local search Algorithm 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. Also, some additional statistical tests were performed for the fitness of the data. In order to conduct solid model calibrations and validations, model output data was compared against the AIMSUN model. The results from the analyses demonstrated that the queue detector distance can affect phase time durations and vehicle queuing lengths on the controlling approach as well as queuing lengths on the metered approach. This study showed that, based on the study for the Old Belair Road roundabout, the total queue length (controlling + metered) will be minimized from 689 to 499 m by the proposed methods when the detector is relocated at 210 m from the roundabout stop line, giving longer phase green times and resulting in decreased intersection queuing lengths.

Modeling of Queue Detector Location at Signalized Roundabouts via VISSIM Micro-Simulation Software in Amman City, Jordan

“…Roundabouts perform well when the flows from all approaches are balanced, with platoons present in the circulating flow, and vehicles from each approach can enter the roundabout. This is because the yield rule limits the approach flows to depend on the circulating flow, and the overall roundabout performance depends on both the circulating flow and the approach flows [13][14][15]18,[22][23][24][25][26][27][28][29].…”

“…For signalized roundabouts, the queue detectors must be installed at the most appropriate location because this can affect the duration of queues at each entry point. An adaptive traffic signal is used and activated when the queue on the controlling approach meets the detector to determine the signal's green/red time [25,26,38]. The standard queue detector location is determined by the Manual of Traffic Roads and Use Management [40] which suggests installing these detectors at certain stopping distances for the 85th percentile approach speed, at 35 m (for a 50 km/h speed limit) to 40 m (for a 60 km/h speed limit) upstream of the stop line.…”

“…In addition, the literature on queue detectors from international countries includes research from the United States [18,37], Australia [25,28,38], Ghana [15], Portugal [24], Albania [36], Spain [41], and Egypt [16]. Meanwhile, one study in Jordan is related to roundabout metering with queue detectors [13].…”

“…In addition, Martin-Gasulla, Garcia [41] investigated the use of the optimal model by placing a queue detector at 50 m as a standard value in the metering roundabouts and found that it improved the capacity of the roundabouts up to 80% and reduced delay (22-56%), with the most effective approach being the controlling approach and shorter amber or blank times of 40 s to quickly improve queue conditions. Moreover, few studies have focused on the optimal local queue detectors at congested roundabouts [25,26]. An, Yue [26] found that using a 380 m detector for the controlling approach and a 320 m detector for the metering approach could reduce queuing length on both approaches.…”

“…An, Yue [26] found that using a 380 m detector for the controlling approach and a 320 m detector for the metering approach could reduce queuing length on both approaches. Moreover, An, Liu [25] showed that installing a detector at 210 m from the roundabout stop line in an adaptive traffic signal system with advanced detectors could reduce the overall queuing length from 689 m to 499 m.…”