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.
Authors: Nan Zou and Jianwei Wang
Conference: Application of Advanced Technology in Transportation (AATT), Chicago, IL
Date: August 13-16, 2006
Abstract:
This paper presents a video-based method for evaluating and validating volume and speed data collected with traffic detectors. Assessing the detector data reliability is a critical task for all Intelligent Transportation Systems (ITS). Their performance will be significantly impacted by the data quality. Most existing studies mainly use volume as the only variable for evaluating the detector quality. A cost-efficient and rigorous method that can concurrently evaluate both volume and speed from the detectors is not available yet. The video-based method presented in this study is both cost-efficient and sufficiently reliable for evaluating detector data for ITS system operations. For example, the performance of a travel time prediction system is very sensitive to the quality of the detector data. This paper will mainly detail the key features of the proposed system and its application in a case study of RTMS detector data on I-70 corridor in Maryland.
Authors: Xianfeng Yang, Gang-Len Chang, Saed Rahwanji
Conference: 92th TRB Annual Meeting in 2013
Unconventional Design: DDI
Purpose:
- Developed a set of planning models for DDI geometry design based on the estimated maximal queue length for each link.
- Developed a signal optimization plan for DDI to achieve signal progressions.
Abstract:
As one of the most popular unconventional interchange designs, diverging diamond intersection (DDI) has received increasing attention over the past decade. This study, responding to the needs, has produced a reliable and convenient system for traffic engineers to perform operational analysis of DDI. The entire system comprises three modules for planning analysis, signal optimization, and operational evaluation. At the planning stage, this system presents a set of empirical equations for engineers to compute the overall interchange delay and identify the potential queue spillback locations in a DDI design. The second module aims to provide the optimal signal plans to prevent the potential queue blockage. This module is unique in its consideration of the interdependent relations between queues at a DDI’s closely-spaced intersections, and the impacts by both geometrical constraints and traffic volumes. Given the traffic volumes, geometrical features, and signal timings, the system’s third module provides users to link a VISSIM-based simulation model to estimate the resulting traffic queues and interchange delays. Numerical analysis with four real-world DDI designs has revealed the effectiveness of the proposed system.
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)