Authors: Zichuan Li, Gang-Len Chang, Suhasini Natarajan
Conference: the 11th International IEEE Conference on Intelligent Transportation System, October 2008 in Beijing, China
Status: Presented
Abstract:
This study presents a mixed integer model for an integrated control between off-ramp and arterial traffic flows. The proposed study intends to minimize the queue spillback from off-ramp to the freeway mainline that may significantly degrade the performance quality of the entire freeway system. In this study, the Cell Transmission Model (1, 2) is employed to capture the traffic propagation on both freeway an surface streets, and to capture the interactions between those two types of flows within the target control boundaries. An efficient solution method based on Genetic Algorithm is provided along with a numeric case study to demonstrate the benefit of this proposed model.

Download (ZichuanLi_ITS_congress_2008.pdf)

Authors: Xin Zhang and Gang-Len Chang
Conference:  TRB 2010 Annual Meeting, January 12, 2010
Status: Presented
Abstract:
This paper presents an integrated model for design of signal plans for massive mixed pedestrian-vehicle flows within the evacuation zone. The proposed model with its embedded formulations for pedestrians and vehicles in the same network can effectively take into their potential conflicts during the evacuation, and generate the optimal routing strategies for guiding evacuees moving toward either the pick-up locations or their parking areas. The core formulations is based on the cell-transmission concept, but the proposed model has been enhanced with the notion of sub cells proposed mainly to capture the complex movements in the pedestrian flows so that it can concurrently optimize both the signals for pedestrian-vehicle flows and the movement directions for evacuees. An illustrating example concerning the evacuation around the M&T stadium area has been used to demonstrate the promising properties of our model.

Download (Zhangxin_TRB_2010.pdf)

Authors: Xin Zhang, Gang-Len Chang, and Alvin Marquess
Abstract:  Evacuating large municipal areas during emergencies in an efficient manner is one of the critical concerns of most responsible management agencies. Previous studies focus mainly on strategic evacuation plans or controls for the passenger cars, giving inadequate attention to those pedestrians community with transit systems or other modes especially in metropolitan areas. This study has developed an evacuation planning module for pedestrians in Washington D.C. and integrates it with the system developed for passenger-car evacuation. The proposed module first guides people to the nearest metro-stations, and then applies the knowledge-based method to choose proper evacuation routes for shuttles to pick up evacuees. It also includes the plans for guiding pedestrians to the nearest evacuation route, and for dispatching shuttles need for their evacuation.

Download (Zhangxin_ITS08_1.pdf)

Authors: Zichuan Li, Gang-Len Chang, and Suhasini Natarajan
Conference: The 11th International IEEE Conference on Intelligent Transportation System, October 2008 in Beijing, China
Status: Presented
Abstract:
Ramp metering is a very important method to improve freeway traffic system performance, but current researches emphasize only on the entering flow control, and not much attention has been paid to the exiting volume at offramp. In some situations, the exiting queue will decrease the overall system performance by a large magnitude. This is demonstrated by simulation experiments and field observation. In this study, a mix integer model is proposed to optimize the arterial and off-ramp control signal timing based on cell transmission traffic propagation model. A Genetic Algorithm based solution algorithm is proposed along with a numerical case study to demonstrate the benefits of this model.

Download (ZichuanLil_IEEE2008.pdf)

Authors: Jie Yu, Yue Liu, Gang-Len Chang, Xiao-guang Yang
Conference: Transportation Research Board 2008
Status: Presented
Abstract:
Choosing proper locations of urban transit hubs has always been one of the critical concerns facing urban transportation planning agencies in China. This study proposes a mixed integer optimal location model for urban transit hubs, with the objective to minimize the demand-weighted total travel time, when explicitly taking into account Traffic Analysis Zones (TAZs) as demand origins or destinations in a target urban area. An Integer Non-linear Programming (INLP) reformulation was developed to significantly reduce the number of variables. Bilinear constraints in the proposed INLP formulation were then re-modeled into linear functions to ensure global optimal solutions obtained. The model was successfully applied to optimize the hub locations in Suzhou Industrial Park, China, with the result of significantly improved system performance. The impacts of several critical factors, such as the number of hubs and the travel time discount coefficient on the system performance are also investigated.

Download (yujie_trb08_1.pdf)

Authors: Jie Yu, Gang-Len Chang, H.W. Ho and Yue Liu
Conference: The 11th International IEEE Conference on Intelligent Transportation System, October 2008 in Beijing, China
Status: Presented
Abstract:
This paper proposes a variation-based online travel time prediction approach using clustered Neural Networks with traffic vectors extracted from raw detector data as the input variables. Different from previous studies, the proposed approach decomposes the corridor travel time into two parts: 1) the base term, which is predicted by a fuzzy membership-value-weighted average of the clustered historical data to reflect the primary traffic pattern in the corridor; and 2) the variation term, which is predicted through the calibrated cluster-based artificial neural network model to capture the actual traffic fluctuation. To evaluate the effectiveness of the proposed approach, this paper has conducted intensive numerical experiments with simulated data from the microscopic simulator CORSIM. Experimental results under various traffic volume levels have revealed the potentials for the proposed method to be applied in online corridor travel time prediction.

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Authors:  Xianfeng Yang, Gang-Len Chang, Yang Lu, and Saed Rahwanji
Conference:  92th TRB Annual Meeting in 2013

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.

Download (Yang_TRB_2011.pdf)

Authors: Xin Zhang and Gang-Len Chang