Authors: Xianfeng Yang, Yao Cheng, Gang-Len Chang
Conference: ITS world congress, 2014
Abstract: Congestion at the downstream of a freeway off-ramp often propagates the traffic queue to the mainline, and thus reduces the freeway capacity at the interchange area. Hence, an accurate queue estimation model can help the traffic engineers to select proper control strategy to mitigate queue spillback at off-ramps. In responds to such a need, this study presents a queue estimation system using dual-zone detectors, where each detector can provide two detection zones. Particularly, the short detection zones are used to count traffic flow rates and the information from long detection zone can indicate the presence of traffic queues. With respect to different congestion levels, the off-ramp queue may be fully discharged during the green time or not. Therefore, this study has developed two queue estimation models for each condition. Based on the field data from the freeway interchange in Zhubei, Taiwan, this study has conducted extensive simulation experiments, and demonstrated the effectiveness of the proposed system on off-ramp queue estimations.