“The goal of the Center for Sustainable Mobility (CSM) at the Virginia Tech Transportation Institute is to establish a center that is recognized both nationally and internationally for its research in the area of sustainable transportation planning and operations with an emphasis on mobility, efficiency, environmental, and safety impacts of transportation infrastructure,” said center director Hesham Rakha. A professor in the Charles E. Via Department of Civil and Environmental Engineering, Rakha has conducted extensive research in the areas of traffic flow theory, traffic control, traffic engineering, traffic modeling, environmental modeling, and safety modeling since the early 1990s.
Much of the center’s talent comes from the CEE faculty including Montasir Abbas, Antoine Hobeika, Pamela Murray-Tuite, Kathleen Hancock, and Linsey Marr. It also employs a number full-time research faculty including: Kyoungho Ahn, Mazen Arafeh, and Ihab El-Shawarby. The center also has three visiting professors, namely WeiDong Wang of Central South University, China; Seong Ik Cho of Electronics and Telecommunications Research Institute, Korea; and Jaeyong Jeong of Mokpo National Maritime University, Korea.
Projects range from improving transit operations to truck lane management
The center’s research projects are numerous. “One project of particular interest that was directed by Ahn and Rakha was concerned with Transit Signal Priority (TSP), an emerging technology capable of enhancing traditional transit services. The research results indicated that a TSP system generally benefits transit vehicles and saves transit times by three to six percent. Future improvements of the TSP system include providing priority to transit vehicles behind schedule and an intelligent transit monitoring system,” Rakha said.
CSM researchers also worked extensively on Interstate 81, one of the top eight truck routes in the U.S. The researchers compared alternative truck and lane management strategies along a significant grade section of I-81 in terms of the transportation system efficiency, energy consumption, environmental, and safety impacts using microscopic traffic simulation. As part of this project they are evaluating different truck lane management strategies along the southbound direction of I-81 between mileposts 143 and 118.
“Have you ever wondered how many vehicles a roadway can handle and how engineers make this determination? Microscopic traffic simulation uses car-following models to capture the interaction among vehicles traveling in the same lane. Data from the simulation enable traffic planners to predict with some accuracy how many vehicles can safely travel on the same road at any given time,” said Rakha. His calibration approach should assist modelers in identifying the optimum values of the microscopic car-following parameters to achieve the desired real-world traffic stream behavior.
Vehicle crashes in high-speed signalized intersections are typically related to “dilemma zone” problems. A dilemma zone can be a period of time or a place in which drivers must make instantaneous decisions. El-Shawarby and Rakha directed a study to verify the current design standards for yellow-phase signaling. The study demonstrated that age-related differences in driver behavior are significant and should be considered in the design of yellow times.
Rakha’s expertise was invaluable also when judging the effectiveness of various systems, from the parking surveillance systems at the Virginia Tech campus to forward collision warning systems which underwent field operational tests to judge their safety and impact on driver behavior.
Weather can cause a variety of impacts on the transportation system. According to Arafeh and Rakha, rain, fog, snow, and freezing rain can have a serious impact on the mobility and safety of the transportation system users. Their research shows that weather has no change on traffic stream jam density, but both rain and snow did impact traffic free-flow speed, speed-at-capacity and capacity and parameters varied with precipitation intensity.
Center is part of a larger research collaboration
CSM is part of a larger collaboration made up of member schools in the Mid-Atlantic Universities Transportation Center (MAUTC). One of the initiatives of this collaboration is the development of a research program which addresses improving the facilitation of safe and efficient movement of freight while reducing the impact of truck traffic on other highway users in Pennsylvania, Virginia, West Virginia, and Maryland.
Other initiatives include the formulation of Strategies to Increase Transportation System Resilience to Congestion Caused by Incidents, as well as studying ways to facilitate no-notice evacuations in emergency situations. Specifically, Hancock, Murray-Tuite, and Rakha are working on developing a research program focusing on Critical Commerce Corridor (3C) Needs to facilitate safe and efficient movement of freight while reducing the impact of truck traffic on other highway users. “The objective of the project is to develop an inventory and functional assessment of the existing transportation system as it relates to freight movements, and identify and evaluate mitigation strategies for existing and potential problem areas. The initial research proposes developing this program for the MAUTC Region 3 which consists of Pennsylvania, Virginia, West Virginia, and Maryland,” said Rakha.
In addition, Abbas and researchers within CSM have conducted research on the evaluation of alternative traffic responsive control strategies to reduce congestion on Northern Virginia arterials. The objectives of the project are to develop traffic responsive control configuration parameters, compare the performance of traffic responsive control to time-of-day operation, and develop guidelines and a field operation manual.
Murray-Tuite is working on alternative methods to reduce traffic congestion caused by traffic incidents, which contributes to 25 percent of traffic congestion. “Murray-Tuite’s study is investigating strategies designed to mitigate the impact of an incident on traffic flow, decrease emergency vehicle response time, and decrease the network recovery time. In this work, opening HOV lanes to all traffic, variable speed limits, re-routing through variable message signs, and re-routing through in-vehicle information systems are four strategies quantitatively evaluated for their effectiveness in mitigating incident-related congestion. The outcomes of this work will benefit transportation professionals and incident managers, as well as emergency response agencies and commuters,” explained Rakha.
Murray-Tuite is also looking at evacuation planning. In no-notice evacuations, such as a terrorist threat, household members may be scattered throughout the transportation network and seek to gather together prior to reaching a final destination. “This gathering process may be facilitated by entities, such as schools, daycare centers, and nursing facilities by the relocation of their charges to more accessible sites. Greater accessibility will help mitigate local congestion, speed the gathering process, and generally lower evacuation times. This study considers only personal vehicle travel for evacuees and will develop a mathematical model that will optimally select these pick-up locations, solve the model for a given network, and evaluate the impacts on evacuation times through simulation. Potential relocation sites will be within 1/2 mile of the starting location. The results of this work will benefit evacuation planners, transportation professionals, and society in general,” Rakha said.
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