چكيده به لاتين
Today, due to the increasing traffic on urban roads, the optimal timing of intersection traffic signals is one of the most important traffic management measures and over the past decades, many efforts have been made to optimize the timing of intersection traffic signals that one of the most important of them is the use of adaptive traffic control systems with instantaneous and adaptive timing feature against of traffic changes at intersections.
One of the most popular adaptive traffic control systems is called SCATS. SCATS architecture and algorithm is designed based on the traffic conditions of the country of manufacture, and of course in its algorithm for some parameters ,such as degree of saturation, calibration capability is considered to calibrate this system based on local traffic conditions. Also the traffic flow in this system in most countries is detected by induction loops and in some countries by cameras. So far SCATS is only adaptive traffic control systems that have been used in Iran signalized intersection control.Therefore, in this study, focusing on SCATS, some approaches to improve its adaptive control operations based on Iran traffic conditions are presented. First, assuming the inaccuracy of SCATS timing and the existence of errors in its lane-based traffic detecting, the current state of Sadi_Jomhuri intersection in Tehran ,which is controlled by SCATS, was simulated by the Aimsun API. Then, using the video of the intersection cameras, the degree of saturation was actually determined by capturing traffic data based on street lines and According to the SCATS algorithm, based on this actual degree of saturation, the timing parameters were calculated and this scenario was implemented in the simulator. According to the results, in comparison with the current situation of the intersection under SCATS control,the latency and stopping time of the intersection have been reduced by 14% and 13%, which indicates the inaccuracy in detecting and the current SCATS timing at the intersection. In order to improve the adaptive control operation of SCATS for the intersection, the saturation degree calibration factor was determined as fixed and variable and then by calculating the timing resulting from applying these factors on the saturation degree of SCATS, both scenarios were implemented in the simulator. According to the results, by applying a fixed and variable calibration factor to the degree of saturation, the saturation degree of intersection approaches is close to reality by 10% and 41%, respectively, and finally leads to a 37% and 26% reduction in latency compared to the current state of the intersection under SCATS control.
Considering the heterogeneous traffic conditions and non-lane based driving behavior in Iran, assuming that the lane-based traffic detecting method of SCATS for these traffic conditions is not accurate, a corrective lanebase detection method was studied for propositing to improve the operation of SCATS, and the actual degree of saturation based on it was calculated and the scenario was simulated. According to the results, the intersection delay with timing based on this detection method was 22% less than timing based on lanebase detection method, which indicates that this detection approach is closer to reality.
