Authors: Mark L. Franz and Gang-Len Chang
Date: July 21, 2014
Abstract:
This research project developed vital operational guidelines for design of a variable speed limit (VSL) system and its integrated operations with ramp metering control in contending with recurrent highway congestion. The developed guidelines can serve as an effective tool for traffic engineers to determine when to activate a VSL control and under what traffic conditions it needs to be supplemented by ramp metering operations to ensure the stability of traffic evolution over the congested highway segment. This report also presents various measures of effectiveness for evaluating the benefits of VSL and its integration with ramp metering control. A VSL control algorithm to compute the time-varying speeds in real time, based on detected traffic conditions, was developed in this study. Extensive simulation experiments, calibrated with the field data from US100 in Maryland, were conducted to evaluate the effectiveness of the developed VSL algorithm. Both the experimental results and sensitivity analyses with respect to key model parameters confirmed that proper implementation of VSL can indeed mitigate the congestion caused by the high-speed variance among vehicles and allow traffic flows to better utilize the available roadway capacity.
Authors: Dr. Gang Len Chang, Dr. Cinzia Cirillo, Nayel R. J. Urena Serulle & Pratt Hetrakul
Date: Dec. 2011
Abstract:
Road pricing has been advocated as an efficient travel demand management to alleviate congestion since the seminal work by Pigou (1920) and Knight (1924) (see Lindsey, 2006, for recent reviews). More specifically, dynamic toll pricing has received greater interest among policy makers and public agencies due to its potential for lowering energy costs for society. Some analytical studies (e.g., Arnott et al., 1990) have found that dynamic toll pricing generally yield greater efficiency gains than static toll pricing because the former reduce queueing delays by altering travelers’ departure times as well as routes.
The construction of the Inter-county Connector (ICC) has certainly offered the prospect of reducing travel time between the I-270 and I-95 corridors, and may potentially alleviate congestion on the I-270 and I-495. Given that the ICC relies on dynamic toll pricing scheme, its daily traffic volumes are governed by individual trip-makers’ perceived time and cost saving in the term of value of travel time (VOT). Moreover, the ability to realistically capture trip-makers’ responses to time-varying road charges in term of willingness to pay (WTP) for toll is essential for predicting network flows and network equilibrium assignment models. These behavioral characteristics of users vary across individuals. Therefore capturing the heterogeneity of users in this regard is critical in predicting the impact of dynamic pricing schemes (e.g., Lu et al., 2008).
This study proposes the model that enables practitioners to integrate user response to dynamic toll pricing. The analysis accounts for cost and time savings perceived by regional drivers and the users’ response to time-varying road charges. More specifically, the study captures difference in behavioral characteristics of the willingness to pay (WTP) for toll across users socioeconomics and trip related characteristics such as time of day,
Authors: Gang-Len Chang & Zichuan Li
Date: Nov. 2010
Authors: Gang-Len Chang & Deepak Shrestha
Date: May.2000
Download (PERFORMANCE-EVALUATION-OF-CHART-AN-INCIDENT-MANAGEMENT-PROGRAM-IN-1997.pdf)
Author: Gang-Len Chang
Date: 2013-2014
Download (NTC-2014-Information-Form_Principal-Investigator_Gang-Len-Chang_September-2014.pdf)
Authors: Jie Yu & Yang Lu
Date: Nov. 14, 2008
Download (Methods-for-Identifying-hazardous-Locations-A-Comparison-study.pptx)
Authors: GANG-LEN CHANG, MARK L. FRANZ & YANG LU
Date: Aug. 2012
Abstract:
The goal of this research was to develop a system that utilizes the dynamic detection technology and to evaluate the performance of this system. The first step of this study was to select an intersection experiencing a high frequency of crashes that could be remedied by a dilemma-zone protection system. Next, a dynamic dilemma-zone protection system was designed using three microwave sensors to track vehicles approaching the intersection on the major approach. The data collected by these sensors were then used in real-time to control the signal logic, providing green extensions and all-red extensions when pre-defined parameters of detected vehicles are met. To evaluate the performance of the system design and the appropriateness of the associated parameters, a field test was conducted. The data analysis included the identification of false called all-red extensions (related to efficiency) and missed all-red extensions (related to safety) to assess the overall performance of the newly installed dynamic dilemma zone protection system.
Download (MD-12-SP708B4J_Dilemma_Zone_Warning_System_Final_Report.pdf)
Authors: WOON KIM & GANG-LEN CHANG
Date: July 2012
Abstract:
This project was focused on identifying potential areas for Maryland’s Coordinated Highway Action Response Team (CHART) to enhance its incident management efficiency and to maximize the resulting benefits under existing resource constraints. Using the information from CHART and the Maryland Accident Analysis Reporting System (MAARS), this research has identified critical factors affecting CHART’s efficiency in incident response and clearance, and produced several reliable models to improve its performance. This research has also produced an optimal allocation model that will enable each operational center to best deploy available patrol vehicles along its responsible highway networks and to select the most cost-benefit fleet size under the resource constraints.
CHART can also apply the set of prediction models developed in this project to estimate the required clearance duration of a detected incident, thereby minimizing the resulting congestion within the impact boundaries via some real-time traffic control and information strategies. Incorporating any of those developed models into current practice will undoubtedly enhance CHART’s operational quality and significantly increase its effectiveness in minimizing non-recurrent congestion in this region.
Authors: WOON KIM , MARK FRANZ & GANG-LEN CHANG
Date: April 2012
Abstract:
To improve traffic conditions on major highways plagued by non-recurrent congestion, most highway agencies have invested their resources in two principal operational programs: incident response and clearance, and traffic impact management. However, even with the wide-spread implementation of such programs, effectively minimizing the traffic impact caused by multi-lane blocked incidents remains a critical and challenging issue for most highway agencies. This research developed a multi-criteria decision-support system for determining the necessity of detour operations during incident management from an overall socio-economic benefit perspective. The developed system enables responsible agencies to consider all associated critical factors with preferred weights, including the direct benefits and operational costs, safety and reliability, accessibility of detour, and acceptability by travelers. This research is part of our developed integrated incident managing system for SHA that has various essential functions, ranging from prediction of incident duration to estimation of operational benefits. This decision module, based on the AHP (analytical hierarchical process) methodology, features its computing efficiency and operational flexibility, allowing users to make necessary revisions if more data are available or more criteria need to be included.
Authors: XIAODONG ZHANG & GANG-LEN CHANG
Date: Nov. 2010
Abstract:
Due to rapid traffic growth in recent years, the Baltimore Beltway (I-695) is now experiencing considerable congestion even after the normal peak periods. Hence, identifying effective tools for contending with worsening congestion on I-695 has emerged as a priority task for the Maryland State Highway Administration (SHA). This study expanded the current traffic simulation laboratory developed by SHA and the University of Maryland College Park (which includes simulators for I-495, I-270, and I-95), and began the construction of the I-695 simulator for use by SHA engineers in performing Baltimore area traffic studies. The simulator system contains the following principal components: (1) an intelligent system interface for input, output, and potential applications; (2) a GIS database for key information related to all network geometric features, driver characteristics, and traffic volume distributions; (3) a microscopic simulation database to model traffic behavior and the daily evolution of traffic patterns; and (4) a knowledge-based expert system module to project the durations of detected incidents. The completed I-695 traffic simulator will be part of the Traffic Simulator System sponsored by SHA, which can be used independently by traffic engineers for the Baltimore area or integrated with other existing simulators (e.g., I- 495, I-270) to analyze the regionwide traffic conditions between the Washington and Baltimore metropolises.
Download (MD-10-SP808B4M-Traffic-Simulator-for-I-695-Report.pdf)