Authors: Yue Liu, Gang-Len Chang, Jie Yu, Yuanyuan Hou, and Saed Rahwanji
Conference: The 11th International IEEE Conference on Intelligent Transportation System, October 2008 in Beijing, China
Status: Presented
Abstract:
This paper presents a macroscopic model of traffic able to replicate the key features occurring at signalized intersections. Different from the previous link or movement based traffic flow models, the proposed model considers explicitly queue accumulation and dissipation at the lane-group level, in order to facilitate modeling the discharging process for shared lanes. In particular, the proposed model also accounts for the blocking effects between different lane groups due to intersection geometric constraints or improper signal settings, which offer potentials for it to be integrated with optimal control models. The performance of the proposed model applied to a real-world intersection under different demand levels appears to be computer-efficient and convincing when validated by a calibrated microscopic simulation program, VISSIM.
Authors: Yue Liu, Gang-Len Chang, and Jie Yu
Conference: the 11th International IEEE Conference on Intelligent Transportation System, October 2008 in Beijing, China
Abstract:
This paper presents the investigation results of driver behavioral patterns during a yellow phase, based on field observations of 1123 drivers at six signalized intersections of high accident frequency in Maryland. By classifying drivers at each intersection into aggressive pass, conservative stop, and normal groups based on their responses (i.e., stop or pass) and their distances to the stop line when the signal turns yellow, the statistical tests with the ordered-probit model clearly indicate the impacts of some critical factors on a driver’s decision. Such factors include: average traffic flow speeds, traffic volume rate, the green split, the number of through and crossing lanes in the target approach, signal coordination, the difference between individual vehicle’s approaching speed and average traffic flow speeds, individual driver’s gender, age, and talking over cell phone or not, individual vehicle’s type and model, and etc. The analysis results offer the basis for assessing the safety conditions at hazardous intersections, and for design of contra measures
Authors: Yue Liu, Gang-Len Chang, Ruihua Tao, Thonas Hicks and Eric Tabacek
Conference: 2008′ TRB Annual Meeting
Abstract:
This paper presents the investigation results of driver behavioral patterns during a yellow phase, based on field observations of 1123 drivers using a specially-designed system at six signalized intersections of high accident frequency in Maryland. By classifying drivers at each intersection into aggressive pass, conservative stop, and normal groups based on their responses (i.e., stop or pass) and their distances to the stop line when the signal turns yellow, the statistical tests with the ordered-probit model clearly indicates the impacts of some critical factors on a driver’s decision. Such factors include: average traffic flow speeds, traffic volume rate, the green split, the number of through and crossing lanes in the target approach, signal coordination, the difference between individual vehicle’s approaching speed and average traffic flow speeds, individual driver’s gender, age, and talking over cell phone or not, individual vehicle’s type and model, and etc. The analysis results offer the basis for assessing the safety conditions at hazardous intersections, and for design of contra measures.
Authors: Xiaorong Lai, Jonathan Reid, Saed Rahwanji and Gang-Len Chang
Conference: 2007′ World Congress on ITS, Beijing in China
Status: Presented
Abstract:
This paper presents the framework and major functions of an integrated program for unconventional arterial intersection design. The proposed program features its integration of a build-in knowledge base and the interactive analysis tools, which aims to provide a better understanding and convenient evaluation of all unconventional intersection types. Various factors, related to traffic analysis, safety concerns, cost estimation, and pedestrian impacts can be included in the evaluation framework through user-friendly interfaces. A case study is presented to show the applicability of the proposed system with respect to the selection and design of unconventional intersections under userspecified scenarios.
Authors: Yue Liu, Gang-Len Chang, Xiaorong Lai and Ying Liu
Conference: 2007′ World Congress on ITS, Beijing in China
Status: Presented
Abstract:
Evacuating large municipal areas during emergencies and disasters in an efficient manner is one of the critical concerns faced by emergency management agencies. This study has developed a corridor-based evacuation planning system for Washington D.C. to design and evaluate various traffic control strategies. The proposed system divides the entire study area into different evacuation corridors, and employs its optimization module along with an embedded macroscopic simulator to generate both signal timings and routing strategies for each corridor in the evacuation area.
Authors: Ying Liu, Xiaorong Lai, Gang-Len Chang
Conference: the 2006 IEEE International Conference on Networking, Sensing and Control, 2006
Abstract:
One popular class of approaches to estimate freeway corridor travel time is based on measured or estimated speed data from roadside detectors. In most estimation practices, using either simulated or actual data, detectors are assumed to evenly distribute with a close spacing of around half mile. Unfortunately, this detector location scheme will be too costly for most freeway corridors under limited budget. To contend with this issue, this paper examines some widely used estimation algorithms under various traffic conditions with different detector spacing, and then proposes a set of strategies for locating detectors. Numerical results, based on traffic conditions on I-70 corridor of Maryland, have demonstrated the promising properties of our proposed strategies under recurrent congestion pattern.
Authors: Ying Liu, Nan Zou, and Gang-len Chang
Conference: the 2005 IEEE International Conference on Intelligent Transportation Systems
Abstract:
The consecutive hurricane attacks to US coastline have drawn significant attentions to evacuation operations related issues. To better prepare the state of Maryland for potential hurricanes, this study presents an emergency evacuation system that integrates both optimization and microscopic simulation methods. The optimization module applies a two-level process to generate the preliminary optimal control plans, which is based on a revised cell transmission formulation for large-scale network applications. Using the optimized results as the initial input, the simulation module takes into account various operational constraints and driver responses that are difficult to be captured realistically with mathematical formulations. The proposed system also features its flexibility for potential users to adjust the optimized plans in both the planning phase and real-time operations based on the results of simulation evaluation. The case study with the data from Ocean City, Maryland during hurricane attacks has demonstrated the potential of the proposed system for evacuation of traffic flows in large-scale networks within a given time window.
Authors: Nan Zou, Pei-Wei Lin, Gang-Len Chang, and Saed Rahwanji
Conference: The 6th Asia-Pacific Intelligent Transportation Systems Forum & Exhibitions, Taipei, Taiwan
Date: October, 2003
Abstract:
This paper presents a real-time incident management system that integrates the knowledge base with a microscopic traffic simulation model. The system consists of five modules: input module, knowledge-based module, prediction module, simulation module, and output module. The knowledge base is used to inventory the operational experience and traffic impact information associated with all recorded incidents. The prediction module is developed to predict the information of maximum queue length and incident duration predictions. The simulation module, developed with design plans for construction, contains traffic volumes and all detailed geometric features for both mainline segments and interchanges.
The proposed system will enable traffic control operators during the incident management period to perform two critical functions: (1) having an immediate estimate of the traffic impacts such as the queue length, average speed due to the detected incident; and (2) performing a subsequent detailed real-time analysis of network traffic conditions under various candidate incident management and/or control strategies with the simulation module.
The simulation results also offer the information between departure time and estimated travel time during the period of incident management. Furthermore, the system can also connect to the on-line detectors so that the real-time information can be used in the prediction and update of the simulation module.
To minimize both the learning and executing efforts of our target users, the integrated simulator is given a GIS-type of map features, allowing the operators to perform the input and output tasks through a user-friendly graphical interface.
Authors: Gang-Len Chang, Mark L. Franz, Yue Liu, Yang (Carl) Lu, and Ruihua Tao
Conference: 92th TRB Annual Meeting in 2013
Abstract:
This paper presents the design and evaluation of a dilemma zone protection system that utilizes the dynamic detection technology to track individual vehicles as they approach an intersection of interest. A high-speed rural intersection in Maryland experiencing a high frequency of crashes was selected for system installation and evaluation. Data collected from 3 sensors, designed specifically for tracking individual vehicles, were deployed along the target approach were used in real time to control the signal logic, providing green or all-red extensions when the pre-defined parameters of detected vehicles are met. To evaluate the performance of the system design and the effectiveness of the associated parameters, a field test was further conducted. The data analysis included the identification of falsely-called red extensions (related to efficiency) and missed red extensions (related to safety) to assess the overall performance of the newly installed system. The field observation results indicate that the newly designed dynamic dilemma zone protection system using an all-red extension offers distinct advantages over traditional systems by providing additional protection to high-speed vehicles even when they are in the “cannot go zone” and make an incorrect decision to go.
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Authors: Andrey A. Petrov, Pei-Wei Lin, Nan Zou, Gang-Len Chang, and Jean Yves Point-Du-Jour
Conference: The 9th World Congress on Intelligent Transportation Systems, Chicago, Illinois
Date: October, 2002
Abstract:
The need to implement an effective Incident Management Systems (IMS) has received increasing attention from 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 consists of analysis of incident characteristics, evaluation of system efficiency and effectiveness, and estimation of benefits to the users. This paper is focused on presenting the results for the year 2000 CHART evaluation.