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.

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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.

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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.

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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.

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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.

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