Center for Sustainable Mobility (CSM)

The Center for Sustainable Mobility (CSM) at the Virginia Tech Transportation Institute(VTTI) is a multi-discipline center that conducts research to develop and evaluate alternative sustainable transportation systems. The center inlcudes the Sustainable Mobility Learning laboratory, a mobile traffic laboratory, and a traffic laboratory.

The center includes four groups: (a) Transportation Systems and Operations Group; (b) Traffic Signal Operations Group; (c) Energy and Environmental Group; and (d) Data Visualization Group.

Current CSM Projects

Modeling Driver Behavior within Traffic Signal Dilemma Zones

Hesham Rakha, Ph.D.,   Ihab-El-Shawarby, Ph.D.

The objectives of this project are: 1. Develop models to characterize driver deceleration, perception-reaction times, and stop/go decisions at the onset of a yellow indication 2. Evaluate the weather impact on driver behavior 3. Develop new procedures for estimating yellow timings 4. Investigate the potential for use of IntelliDrive applications to enhance signalized intersection safety and performance.

Travel Time Reliability Modeling

Hesham Rakha, Ph.D.

The objectives of this project are: 1. Develop a novel multi-stage model for travel time reliability evaluation and reporting. 2. Construct a simulation test bed along a section of I-66 to investigate the impact of different factors on travel time reliability. 3. Construct a database of field loop detector and incident data for the same I-66 study section. 4. Develop a multi-stage model to quantify the impact of incidents on travel time reliability using the field and simulation test bed. 5. Develop algorithms to use vehicle probe data to estimate dynamic roadway travel times.

Energy and Environmental Modeling of Ground Transportation Systems

Hesham Rakha, Ph.D.,   Kyoungho Ahn, Ph.D.

The objectives of this project are to: 1. Develop energy and emission models for light- and heavy-duty vehicles 2. Assess the energy and emission impacts of alternative traffic calming measures 3. Assess the impact of high emitting vehicles on Green House Gases (GHGs) 4. Evaluate the energy and environmental impact of roundabouts. This characterization is critical to any successful Vehicle Infrastructure Integration (VII) or Advanced Traveler Information System (ATIS) initiatives.

Driver Route Selection and Response to Traveler Information

Hesham Rakha, Ph.D.

Within the context of transportation modeling, driver route selection behavior is typically captured using mathematical programming. These approaches assume that drivers have full knowledge of the transportation network state in attempting to minimize some objective function. Typically, drivers are assumed to either minimize their travel time (user equilibrium) or minimize the total system travel time (system optimum). Full description

Microscopic Analysis of Traffic Flow in Inclement Weather Conditions

Hesham Rakha, Ph.D.

Inclement weather is one of the key causes of congestion because drivers typically attempt to drive at lower speeds with increased caution. Additionally, inclement weather contributes to more than 1.5 million crashes every year. Full description

Data Mining and Gap Analysis for Weather Responsive Traffic Management Program

Hesham Rakha, Ph.D.,   Kyoungho Ahn, Ph.D.

During the past several years, the Federal Highway Administration's (FHWA) Road Weather Management Program (RWMP) has carried out a series of studies to gain a better understanding of travelers' behavior and responses to inclement weather conditions.
Full description

Empirical Studies on Traffic Flow in Inclement Weather

Hesham Rakha, Ph.D.,   Ihab-El-Shawarby, Ph.D

The goal of this federally sponsored project is to characterize the impact of inclement weather including: precipitation type, precipitation intensity, and visibility level of traffic flow behavior and key traffic stream parameters including free-flow speed, speed-at-capacity, capacity, and jam density.

Developing Eco-Routing Strategies

Hesham Rakha, Ph.D.,   Kyoungho Ahn, Ph.D.

Dynamic traffic routing is defined as the process of dynamically selecting the sequence of roadway segments from a trip origin to a trip destination. Dynamic routing typically entails using time-dependent roadway travel times to compute this sequence of roadway segments. As with the general case of modeling human behavior, modeling driver travel behavior has always been complicated, never accurate enough, and in constant demand for further research. Full description

Developing Eco-Driving Strategies

Hesham Rakha, Ph.D.,   Kyoungho Ahn, Ph.D.

Numerous variables influence vehicle energy and emission rates. These variables can be classified into six broad categories, as follows: travel-related, weather-related, vehicle-related, roadway-related, traffic-related, and driver-related factors. Full description

Hardware-in-the-Loop Evaluation of the Bendix ESP System for Tractor Semi-Trailers

Hesham Rakha, Ph.D.,   Jared Bryson

The objective of this project is to evaluate the potential safety benefits of the Bendix ESP system for heavy trucks using hardware-in-the-loop (HIL) simulations. The evaluation attempst to quantify safety benefits, and also provide relative safety performance between different pre-crash scenarios. The project will be limited to application of the Bendix ESP in predetermined 5-axle tractor semi-trailer configuration. The approach used in the study will include HIL simulations using the real-time version of TruckSim (TruckSim RT). The TruckSim model will provide all necessary signals to the brake system hardware. Additional interfaces and signal conditioners will be required. Bendix will be providing support in developing the software/hardware interface.

SHRP2 L10 Study: Feasibility of Using In-Vehicle Video Data to Explore How to Modify Driver Behavior that Causes Non-Recurring Congestion

Hesham Rakha, Ph.D.

The objective of this project is to determine the feasibility of using existing in-vehicle video to make inferences about driver behavior that would allow the investigation of the relationship of observable driver behavior to non-recurring congestion in order to improve travel time reliability. The use of other data sources, such as infrastructure-based video and traffic data for example, will also be evaluated for the potential to identify ways to modify driver behavior to improve travel time reliability.

Intelligent Parking Management Strategies

Hesham Rakha, Ph.D.,   Alejandra Medina-Flintsch

The proposed study utilizes the Virginia Tech campus to develop a prototype parking monitoring and management system that will manage, enforce and characterize on-campus parking facility utilization. Eventually, a system will be integrated within ATIS to display parking data in real-time to the general public in an attempt to reduce traffic congestion on campus.

Signal Prioritization

Hesham Rakha, Ph.D.,   Kyoungho Ahn, Ph.D.

This project assesses the merits of signal prioritization for emergency and transit vehicles in the Washington, DC area

Previous CSM Projects

Access Control Design on Highway Interchanges

There are a number of publications that provide guidance at the national level with regard to the distance from the interchange ramps in which access should be controlled on the crossroad. These publications include suggested spacing between the interchange ramp and the first right-in/right-out access, the first unsignalized full access, and the first signalized intersection. The research investigates the operational impacts of varying access lengths based on field observations, data collection and analysis, and microscopic simulation. Crash experience at existing interchanges with varying access control lengths will be evaluated to help define the influence area and possibly be used to develop safety analysis procedures to predict crashes for varying configurations. The research will synthesize the state of the practice in other states. Older driver reaction and decision making times, vehicle acceleration and deceleration, signing and markings, and potential pedestrian conflicts will also be considered in the investigation of the optimal limited access length as measured from the ramp terminals.

Access Control Design on Highway Interchanges

There are a number of publications that provide guidance at the national level with regard to the distance from the interchange ramps in which access should be controlled on the crossroad. These publications include suggested spacing between the interchange ramp and the first right-in/right-out access, the first unsignalized full access, and the first signalized intersection. The research investigates the operational impacts of varying access lengths based on field observations, data collection and analysis, and microscopic simulation. Crash experience at existing interchanges with varying access control lengths will be evaluated to help define the influence area and possibly be used to develop safety analysis procedures to predict crashes for varying configurations. The research will synthesize the state of the practice in other states. Older driver reaction and decision making times, vehicle acceleration and deceleration, signing and markings, and potential pedestrian conflicts will also be considered in the investigation of the optimal limited access length as measured from the ramp terminals.

Intersection Collision Warning Field Study

In a recently completed study in the FHWA Highway Driving Simulator, it was found that about 70 percent of drivers stopped for an unanticipated warning that was intended to cause them to slow or stop to avoid collision with a hypothetical red-light violator. Ten to 20 percent more drivers responded as desired when the warning was distinctly different from a normal traffic signal phase change. Therefore, it was recommended that a field validation study be conducted using a warning similar to the most effective warning condition in the simulation. Because drivers in the simulator braked harder (decelerated faster) than is usually observed in field studies, verification was needed that drivers in actual vehicles will respond to violator warnings in a manner that will avoid collisions. The objective of the study is to partially replicate the simulator study to verify that drivers will respond to red-light violator warnings with sufficient speed and intensity to avoid a collision with the violator. The tasks of the study include: 1) conduct a field study on the Smart Road test facility using a total of 60 test subjects; 2) characterize driver behavior at the onset of a yellow phase; 3) characterize break reaction times at signalized intersection approachses; 4) characterize driver deceleration behavior at signalized intersection approaches; and 5) develop models to replicate driver stop/go behavior at the onset of a yellow phase.

Addressing I-81 Transportation Issues

Virginia's mountainous terrain and the large number of trucks that travel on the state's major highways have resulted in reductions in roadway capacities and levels of service. Researchers at Virginia Tech are studying this problem and its effects on traffic stream behavior. This research effort is important because current procedures for modeling trucks in the 2000 Highway Capacity Manual only consider a single truck of weight-to-horsepower ratio 200 lb/hp. The research effort develops vehicle dynamics models for modeling truck acceleration behavior, models the interaction of trucks and automobiles, enhances the HCM truck performance curves, evaluates the safety hazard of I-81, and evaluates alternative lane and truck management strategies.

Traffic Modeling Issues

The objective of this research effort is to use GPS detection technology, together with fully-equipped vehicles, to characterize vehicle behavior in order to provide data that would allow for the enhancement of current state-of-the-art microscopic simulation tools. To achieve this objective, data are being collected along the Smart Road and along typical urban arterial and freeway sections. The data being collected include vehicle speed, acceleration, throttle level, braking indicator, fuel consumed, and emissions every second.

Addressing Urban Network Transportation Issues

The majority of transportation problems occur within urban environments. In order to manage and enhance the flow of urban traffic, transportation professionals need tools to evaluate, predict, and control the ever-growing number of vehicles on the roads. Various methods for controlling traffic are emerging, including transit signal priority, in which the timing of the traffic signal is modified to accommodate transit vehicles; adaptive signal control, in which the timing of the traffic signal adjusts according to traffic information monitored through roadway sensors; ramp metering; and toll roads. The project involves 1) developing procedures to estimate the delay upstream of bottlenecks; 2) develop analytical models to estimate the number of stops at over-saturated signalized intersection approaches; 3) develop procedures to calibrate traffic dispersion models; 4) develop procedures to model traffic dispersion microscopically; 5) develop mesoscopic models to estimate traffic stream energy consumption and emissions; and 6) develop analytical procedures to calibrate commercially available microscopic traffic simulation software.

Developing a Fully Instrumented Test Facility

The goal of this project is to develop a comprehensive instrumented test bed in the town of Blacksburg to achieve the following objectives: 1) Serve as a real-life test facility for the evaluation and enhancement of traffic flow theory; 2) Develop a database of field data for conducting research on alternative means of disseminating real-time traveler information to the public; 3) Serve as a real-life test facility for enhancing and developing tools for the evaluation of network-wide energy and environmental impacts of operational-level transportation projects; 4) Serve as a real-life test facility for enhancing and developing tools for quantifying the noise impacts of operational-level transportation projects; 5) Serve as a test facility for evaluating emerging ITS technologies that can benefit transit operations; 6) Serve as a test bed for evaluating emerging surveillance and communication technologies; and 7) Serve as a unique educational tool that will allow practitioners, undergraduate students, and graduate students to access and analyze real-life traffic data

Inclement Weather Impacts on Traffic Stream Behavior

It is common knowledge that inclement weather affects traffic stream parameters and behavior. However, it is not clear how these various forms of inclement weather impact traffic stream parameters. Consequently, this research effort combines weather and traffic data to quantify the impact of inclement weather on traffic stream parameters considering three geographic locations in the USA, namely, Baltimore, Minneapolis, and Seattle. The study will develop analytical models to account for inclement weather impacts on roadway capacity and free-flow speed. These factors will be similar to the Highway Capacity Manual (HCM) procedure heavy vehicle, lane width, and lane-changing intensity adjustment factors.

Analytical Procedures for Estimating Capacity of Feeway Weaving Sections

The freeway weaving analysis procedures in the 2000 Highway Capacity Manual (HCM) are based on research conducted in the early 1970s through the early 1980s. Subsequent researches have shown that the methods' ability to predict the operation of a weaving section is limited. Consequently, this research effort utilizes the INTEGRATION software to estimate the capacity of weaving sections. Subsequently, analytical procedures are developed using the simulated data to estimate the capacity of high intensity lane-changing sections including weaving, merge, and diverge sections.

Dynamic Roadway Travel Time Algorithm Development

The project develops algorithms that estimate dynamic roadway travel times. The tasks of the project include: 1) develop algorithms for matching license plate readings; 2) develop procedures to estimate trip travel time variability from segment travel time measurements; 3) characterize daily traffic demand variability; and 4) develop procedures to estimate space-mean-speed from loop detector time-mean-speed measurements.

Integrating Transit Signal Priority and Adaptive Traffic Signal Control

The project investigates the merits of integrating transit signal priority (TSP) within an adaptive traffic signal control system along the Columbia Pike corridor. The tasks of the project include 1) install GPS units on five buses and sample automobiles traveling along the corridor to record second-by-second speed data; 2) develop emission models for transit vehicles; 3) estimate different MOEs from the data; and 4) conduct a statistical analysis of the aggregate data to quantify the impacts on TSP on the various MOEs.

Enhancing High Emitter Vehicle Screening Procedures

This project aims at refining the practice of screening high emitting vehicles, by supporting the Virginia Department of Environmental Quality on three tasks: 1) converting emission concentration measurements to emission rates; 2) devising techniques to account for the lag between speed/acceleration measurements and tailpipe emission measurements, and 3) devising techniques for screening high emitting vehicles.

Addressing VDOT Surveillance Needs

This project was a collaborative effort between Virginia Tech and the University of Virginia. The objective of the study was to develop alogrithms to locate surveillance technology and estimate dynamic roadway travel times. The project tasks included: 1) estimate dynamic roadway travel times using Automative Vehicle Identification (AVI) data; 2) develop algorithms to optimally locate AVI surveillance instrumentation using the Reformulation Linearization Procedure (RLT); and 3) develop a Genetic Algorithm to optimally locate surveillance instrumentation.

I-77/I-81 Interchange Modeling Study

This study involved the modeling of alternative I-77/I-81 overlap designs using microscopic traffic simulation. The tasks of the project included: 1) compare CORSIM and INTEGRATION for the modeling of bottlenecks and 2) develop calibration procedures for the CORSIM software.

Fuel Doctor Evaluation

The Fuel Doctor technology relates to a device and process provided for treatment of a hydrocarbon or fossil fuel which is to be combusted in a combustion chamber to improve combustion of the fuel in the combustion chamber by turbulently treating the fuel with a plurality of fields of magnetic flux and subjecting the fuel to a field of differing standard electrochemical reduction potentials. The device is adapted to be connected in-line in a fuel supply line of the combustion chamber. The objective of the study was to evaluate the impact of the Fuel Doctor technology on vehicle fuel consumption and emissions.

Fuel Doctor Evaluation

The Fuel Doctor technology relates to a device and process provided for treatment of a hydrocarbon or fossil fuel which is to be combusted in a combustion chamber to improve combustion of the fuel in the combustion chamber by turbulently treating the fuel with a plurality of fields of magnetic flux and subjecting the fuel to a field of differing standard electrochemical reduction potentials. The device is adapted to be connected in-line in a fuel supply line of the combustion chamber. The objective of the study was to evaluate the impact of the Fuel Doctor technology on vehicle fuel consumption and emissions.

Metropolitan Model Deployment Initiative Evaluation

This project was intended to provide a comprehensive evaluation of the impact of the Metropolitan Model Deployment Initiatives (MMDI) in Seattle, Phoenix, and San Antonio . As part of his involvement in the MMDI evaluation, Dr. Rakha headed a team that quantified the impact of traffic signal coordination and variable message signs on the system throughput, energy and emissions, and safety. In doing so the team modeled a portion of Phoenix and some portions of San Antonio . Dr. Rakha was also involved in enhancing current energy and emission models together with current safety models. Furthermore, Dr. Rakha was actively involved in research in the area of driver behavior in terms of time of departure, mode of travel, and route of travel.

Intelligent Infrastructure Deployment Analysis System (IDAS)

The objective of the project was to develop a sketch planning tool that assists Metropolitan Planning Organizations (MPO's) and Departments of Transportation (DOT's) in assessing the benefits and costs of Intelligent Transportation System (ITS) and non-ITS options. Partners involved in the project included Oak Ridge National Lab, Cambridge Systematics, and the Center for Transportation Research at Virginia Tech. As part of his work with IDAS, Dr. Rakha was part of a team that developed macroscopic emission and safety models.

Adaptive Curise Control Evaluation

This project involved evaluating the safety and throughput benefits of Adaptive Cruise Control (ACC) systems using field data that were gathered by the University of Michigan. As part of his involvement, Dr. Rakha compared the workload involved in the usage of conventional cruise control to ACC. Dr. Rakha was part of a team that developed a framework for the evaluation of the safety impacts of ACC.

SWIFT Architecture Evaluation

The project entailed an evaluation of the SWIFT (Seattle Wide-Area Information For Travel ers) system architecture. The SWIFT system disseminated real-time traffic information via an FM sub-carrier. Three reception devices received the information, namely: Delco navigation units, PC laptops, and Seiko MessageWatch™ wrist watches. SAIC was responsible for evaluating the SWIFT system and Dr. Rakha was the Co-PI in the system architecture evaluation. This evaluation study involved a number of field tests, questionnaires, and a review of the system architecture.

Genesis Modeling Study Evaluation

Dr. Rakha conducted the Genesis modeling study in the twin cities Minneapolis/St. Paul. The Genesis study involved evaluating the traffic and environmental impacts of Personal Communication Devices (PCD's) including pager systems on the overall performance of traffic. The Genesis system was evaluated using a combination of operational field and modeling tests. Field experiments and surveys collected data and information on the Genesis test drivers. A total of 403 test vehicles were allowed to traverse the Minneapolis/St. Paul network for an entire year. The desire to examine other unobservable factors resulted in the inclusion of a modeling activity using the INTEGRATION model. The INTEGRATION model was initially calibrated to the existing conditions, and then utilized to extrapolate results for conditions that were not encountered during the field test.

TravTek Modeling and Safety Study

Dr. Rakha was involved in evaluating the traffic and environmental impacts of the TravTek route guidance system in Orlando , Florida using the INTEGRATION simulation model. The TravTek evaluation study is the largest field evaluation of a Dynamic Route Guidance System (DRGS) in North America. As part of the TravTek evaluation study, Dr. Rakha analyzed the I-4 ( Orlando , Florida ) Freeway Traffic Management System (FTMS) data, assisted in evaluating the safety of the TravTek route guidance system, and conducted the modeling study of the TravTek system using the INTEGRATION simulation model.

Develop Analytical Procedures for Estimating Capacity of Weaving Sections

This research effort used the INTEGRATION software to estimate the capacity of freeway weaving sections.

ITS Approaches to Mitigating Truck Impacts on Traffic Stream Flow

The study investigated the feasibility of alternative ITS applications along the I-81 corridor and quantified the mobility, throughput, energy, environmental, and safety benefits of such ITS applications.

Addressing I-81 Transportation Issues

This project addressed the following issues concerning I-81: evaluating safety hazards in relation to other U.S. highways, evaluating the operation of truck weigh stations, and quantifying the impact of trucks on the surrounding traffic along various graded sections.

Addressing Urban Network Transportation Issues

The objective of this research effort was to develop traffic flow theory and control to address the unique issues of urban networks.

Traffic Modeling Issues

The objective of this research effort was to use GPS detection technology, together with fully-equipped vehicles, to characterize vehicle behavior in order to provide data that would allow for the enhancement of current state-of-the-art microscopic simulation tools.

VDOT Surveillance Needs

The objective of this project was to estimate dynamic roadway travel times using loop detector, video detection, and Automatic Vehicle Identification (AVI) technologies.

Intersection Collision Warning Field Study

The objective of this study, completed in the FHWA Highway Driving Simulator, was to partially replicate the simulator study to verify that drivers will respond to red-light violator warnings with sufficient speed and intensity to avoid a collision with the violator.