Authors: Yue Liu, Gang-Len Chang
Conference: The 19th International Symposium on Transportation and Traffic Theory
Abstract:
This paper presents a generalized diversion control model for freeway incident management that is capable of concurrently optimizing the detour rates and arterial signal timings over multiple roadway corridor segments between the freeway and its neighboring arterial. To capture various operational complexities due to the interactions between multiple diversions, this study has extended the model developed in our previous work (Liu et al., 2009), and integrated it in the overall corridor optimization process. The proposed generalized model based on reliable sensor data can produce the following three types of control parameters: 1) a set of critical upstream off-ramps and downstream on-ramps to be used for detour operations; 2) dynamic diversion rates and detour destinations for traffic at those critical upstream off-ramps within the control boundaries; and 3) arterial signal timings during the control time period. Numerical tests with a hypothetical corridor network have demonstrated the potential of the developed model for use on incident management.
Authors: Xiaorong Lai, Ying Liu, and Gang-Len Chang
Conference: the 11th IFAC symposium on Control in Transportation Systems, 2006
Abstract:
This paper presents a mixed-integer model for design of arterial signal control strategies during emergency evacuation. The proposed model can effectively take into account various complex operational issues such as critical intersection selection, demand rerouting, and signal timing. The control objective is to maximize the efficiency of the primary evacuation arterial, but not incur excessive waiting time and queues on its side streets. To evaluate the effectiveness of the proposed model under various demand levels and control objectives, this study has employed one major evacuation corridor in Washington D.C. as the target route for numerical experiments. The results of extensive simulation experiments reveal that the proposed method for signal optimization offers the potential for real-world applications.
Authors: Yue Liu, Gang-Len Chang and Ruihua Tao
Conference: 2007′ IEEE Conference on Intelligent Transportation Systems, Seattle, WA
Status: Presented
Abstract:
This paper presents a video-based system for measuring dynamic dilemma zones at signalized intersections. The proposed system is cost-effective and sufficiently reliable for measuring various critical information associated driver behavior, including the speed before-and-after the yellow phase, the acceleration/deceleration rates and the approximate reaction time to an encountered yellow phase, and differences in driving patterns. Such information is critical for understanding the spatial distribution of dynamic dilemma zones and the design of strategies to improve intersection safety. This paper details the key components of the proposed system and the systematic procedures for field operations, data extraction, and system validation. The estimation of dilemma zones based on 1123 field observations of drivers’ responses via the proposed system at six intersections of high accident frequency are also reported in this paper.
Authors: Ying Liu, Peiwei Lin, Nan Zou, Gang-len Chang, and Jean Yves Point-Du-Jour
Conference: The 2004 IEEE International Conference on Networking, Sensing and Control, Taipei, Taiwan, March 2004.
Abstract:
The need to implement an effective Incident Management Systems (IMS) has received increasing attention by general public, media and policy makers, that in turn has required transportation agencies to perform a rigorous evaluation over any implemented plan. Since 1996, the Maryland State Highway Administration (MSHA) has conducted a comprehensive evaluation of its incident response and management program, named CHART. The evaluation study consisted of two phases. Whereas the focus of Phase 1 was on the reliable assess of system performance including incident detection, response, clearance and duration, the core of Phase 2 was to develop the methodology and to estimate resulting system benefits from data available in the CHART incident operations record.
Authors: Xianfeng Yang, Gang-Len Chang, Yang Lu, and Saed Rahwanji
Conference: 92th TRB Annual Meeting in 2013
Unconventional Design: CFI
Abstract:
Despite the increasing use of continuous flow intersections (CFI) to contend with the congestion caused by heavy through and left-turn traffic flows, a reliable and convenient tool for the traffic community to identify potential deficiencies for CFI’s geometry design are not available yet. This is due to the unique geometric feature of CFI which comprises one primary intersection and several crossover intersections. The interdependent relation between the traffic delays and queues at a CFI’s five closely-spaced intersections cannot be fully captured with the existing analysis models developed for conventional intersections. In response to such a need, this study presents a comprehensive analysis for the overall CFI delay, identifies the potential queue spillback locations, and develops a planning framework for CFI’s geometry designs. To facilitate the application of our proposed models, this paper also includes a case study of a CFI at intersection MD 4 and MD 235 conducted by Maryland State Highway Administration.
Authors: Xiaorong Lai, Minseok Kim, Gang-Len Chang, and Saed Rahwanji
Conference: The PTV America Users Group Meeting 2007
Abstract:
Rising as a new alternative to relieve arterial congestion, the UAID concept generally attempts to enhance operational efficiency at major arterial intersections by reducing the negative impacts of turning movements through various innovative intersection designs. General principles of operation and management strategies of the UAID include: 1) an emphasis on throughtraffic movements along the arterial, 2) a reduction in the number of signal phases (e.g., left-turn arrow phases), and 3) a reduction in the number of intersection conflict points. As a collaborative research effort among the University of Maryland at College Park, Maryland State Highway Administration, and Parsons Brinckerhoff Inc., the knowledge base web interface (https://attap.umd.edu/uaid.php ) has been built to help traffic engineers, community planners, and elected officials to consider the UAID as a feasible solution for relieving arterial congestion and to select proper unconventional design schemes given
actual traffic patterns.
Authors: Pei-Wei Lin (pwlin@wam.um.edu) and Gang-Len Chang
Conference: the 9th International Conference on Applications of Advanced Technology in Transportation, Chicago, IL
Date: August 13-16, 2006
Abstract:
This study presents a robust algorithm that can deal with the incomplete volume information so as to significantly improve the estimation accuracy. To tackle the inevitable measurement data error or only partially available information, the proposed robust algorithm converts each model input data into one interval with its upper and lower bounds best approximated from historical data or/and prior knowledge. A simulated system, the I-95 freeway corridor between I-495 and I-695, has been created to generate example data and to perform the numerical evaluation of the developed robust algorithm.
Authors: Ying Liu and Gang-Len Chang
Conference: The 9th international conference on Applications of Advanced Technologies in Transportation Engineering, 2006
Abstract:
This study presents a new approach for estimating travel time information along freeway corridors, which experience recurrent congestions but have only a limited number of available detectors due to budget constraints. The proposed iterative estimation procedure, based on a set of empirically calibrated regression models, intends to rebuild the relations between travel times and accumulated flows within each segment of the target freeway corridor. To evaluate the effectiveness of the proposed methodology, this study has conducted extensive numerical experiments with simulated data from a CORSIM simulator. Experimental results under various traffic volume levels have revealed that the proposed method offers a promising property for use in travel time estimation based on sparsely distributed sensors.
Authors: Ying Liu, Xiaorong Lai, Gang-len Chang
Conference: the 8th International Conference on Applications of Advanced Technology in Transportation, Chicago, IL
Date: May 26-28, 2004
Abstract:
This paper has investigated critical issues associated with Optimal Detector Locations for OD matrix estimation, including a discussion of limitations embedded in existing models and heuristic algorithms. Grounded on the core methodology of existing literature (Yang, 1998), this paper has proposed a heuristic algorithm for identifying the optimal set of detector locations under a given budget constraint for effective OD matrix estimation. The algorithm tries to simultaneously optimize OD coverage, net OD flow intercepted and link-OD flow fraction. Our numerical experiment results have indicated that the proposed algorithm is quite promising for potential applications.
Authors: Yue Liu, Gang-Len Chang, Ruihua Tao, Eric Tabacek, and Thomas Hicks
Conference: Application of Advanced Technology in Transportation (AATT), Chicago, IL
Date: August 13-16, 2006
Abstract:
Understanding the response and acceleration/deceleration rate of driving populations to a yellow phase is essential for estimating the dynamic distribution of intersection dilemma zones. This paper presents a video-based method for measuring driver responses during a yellow phase, including their speed evolution profile, acceleration/deceleration rate, and the approximate reaction time. Such information is critical for understanding the spatial distribution of dynamic dilemma zones and the design of strategies to improve intersection safety. This paper details the key components of the proposed system and the systematic procedures for both field operations and data extraction. The results of a rigorous validation with an advanced experimental vehicle provided by Nissan are also reported in this paper.