Authors: Gang-Len Chang & K.P. Kang
Date: July 2008
Abstract:
To improve traffic mobility and safety in highway work zones, this study has focused mainly on developing advanced merge and speed control strategies, including both their individual and integrated control algorithms. Based on the deficiencies and limitations of existing work zone control operations, this research has made contributions mainly on the following four regards:(1) understanding traffic flow characteristics under work zone traffic conditions with empirical data and identifying their interrelations; (2) developing an operational model for computing the optimal set of thresholds for DLM and its implementation algorithm; (3) Proposing an optimal speed limit control model that can maximize the throughput of a lane-closure highway segment with a set of dynamically adjusted speed limits; and (4) constructing an integrated operational algorithm to take the advantage of the strengths of DLM and VSL controls. The simulation results have demonstrated that the developed DLM and VSL controls have better performance in terms of traffic mobility and safety than their existing controls based on static approaches, and also shown that the proposed integrated control of the DLM and VSL control has more promising properties than each individual control.
Authors: Gang-Len Chang & Kyeong-Pyo Kang
Date: Aug. 1, 2005
Abstract:
This project presents the evaluation results of three ITS technologies offered by system providers for improving operational efficiency and traffic safety at highway work zones. The first is an integration of variable message signs (VMS) and sensors that function to guide traffic approaching the work zone via dynamic late merge (DLM) operations. Observations of the day-to-day traffic patterns over the work zone under DLM control clearly indicate that such a control system has the potential to significantly increase the work zone throughput, reduce the queue length, and vehicle delay if all sensors and VMS are placed at proper locations.
The second technology is a travel time prediction system that employs traffic data from sensors to project the travel time from a set of given origins to the target destination. The field test results from the highway segment along EB I-70 from MD 32 to I-695 reveal that prediction of travel times under moderate and stable traffic conditions is likely to yield an acceptable level of reliability. However, much remains to be improved for achieving reliable prediction of travel times under congested and unstable traffic flows.
The third target technology under evaluation is a license plate recognition (LPR) system that computes the travel time between an O-D pair based on the entry and exit times of a matched license plate number. The performance of the LPR system on the I-95 testing site shows that the employed technology for LPR cannot yield a sufficient level of license recognition rate for reliable estimation of travel times unless the target highway segment is under congested traffic conditions and vehicles are moving under relatively slow speeds. Besides, the LPRS may not be a cost-effective system for use in local arterials with a large percentage of turning flows, which often causes the LPRS to have a low match rate.
Download (MD-05-SP208B4H-Evaluation-of-ITS-Deployments-for-Work-Zone-Operations-Report.pdf)
Authors: Gang-Len Chang, Hua Xiang & Chi-Sheng Chou
Date: June 2004
Abstract:
This study has investigated the interrelations between crash rates, signal yellow times, driver characteristics and vehicle performance characteristics at signalized intersections, based on field observations of 732 drivers at nine intersections across five counties in Maryland. It has been found that driver responses during the yellow signal phase can be classified into four distinct types: “aggressive pass,” “conservative stop,” “normal stop,” and “normal pass.” Their response differences are due not only to discrepancies in individual characteristics, but also a variety of traffic environmental factors. The collective impacts of such factors have been evaluated with an ordered-probit model. In addition, based on the speed evolution data recorded from each observed driver, this study further analyzed the deceleration/ acceleration rates of drivers responding to yellow-light phases. Such information provides valuable data for computing the distribution of intersection dilemma zones under various types of driving populations and vehicle types.
Download (MD-04-SP308B4L-Dilemma-Zone-Warning-System-Phase-I-Report.pdf)
Abstract:
Road pricing has widely been considered by system planners for relieving congestion and generating revenue. The design and evaluation of different road pricing schemes are always necessary for the decision makers to ensure the potential beneficiary of road pricing and the practical implementation of the scheme. This study presents an evaluation procedure based on the use of continuum modeling approach for addressing the road pricing feasibility problem in Baltimore Metropolitan Region. In this study, Baltimore City is considered as the central business district (CBD) and the corresponding user-equilibrium, system-optimal and cordon-based charging models are setup and solved. Sensitivity analyses of total demand, total toll collected, social benefit and the location/shape of the charging cordons for this proposed model with respect to the input parameters are also completed. The study demonstrates the potential applicability of using continuum modeling approach for road pricing feasibility study in Baltimore Metropolitan Region.
Author: Gang-Len Chang & Zhuan Li
Date: June 2010
Authors: Xianfeng Yang , Yang Lu & Gang-Len Chang
Date: March 2011
Authors: Gang-Len Chang, Ying Liu , Ali Haghani , Abbas M. Asshar
Date: June 2007
Author: Elham Sharifi
Date: 2008