Prediction/Causality Tradeoffs and Data Size Issues in Transportation Modeling: The Example of Highway-Safety Analysis
Associate Dean for Research, College of Engineering
Professor of Civil and Environmental Engineering
University of South Florida
May 21, 2021 at 4:40 p.m. ET
Abstract: The analysis of transportation data is largely dominated by traditional statistical methods (standard regression-based approaches), advanced statistical methods (such as models that account for unobserved heterogeneity), and data-driven methods (machine learning, neural networks, and so on). In the analysis of highway safety data, these methods have been applied mostly using data from observed crashes, but this can create a problem in uncovering causality since individuals that are inherently riskier than the population as a whole may be over-represented in the data. In addition, when and where individuals choose to drive could affect data analyses that use real-time data since the population of observed drivers could change over time. This issue, the size of the data (which can often influence the analysis method), and the implementation target of the analysis imply that analysts must often tradeoff the predictive capability (dominated by data-driven methods) and the ability to uncover the underlying causal nature of crash-contributing factors (dominated by statistical and econometric methods). However, the selection of the data-analysis method is often made without full consideration of this tradeoff, even though there are potentially important implications for the development of safety countermeasures and policies. This talk provides a discussion of the issues involved in this tradeoff with regard to specific methodological alternatives, and presents researchers with a better understanding of the trade-offs often being inherently made in their analysis.
Bio: Fred Mannering is currently the Associate Dean for Research in the College of Engineering and a Professor of Civil and Environmental Engineering (with a courtesy appointment in Economics) at the University of South Florida. He received his undergraduate degree from the University of Saskatchewan, masters from Purdue University, and doctorate from the Massachusetts Institute of Technology. He was previously a professor at Penn State, A professor and Department Chair at the University of Washington, and School Head and Chaired professor at Purdue University. His research interests are in the application of econometric and statistical methods to the analysis of highway safety, transportation economics, vehicle demand, travel behavior and a variety of other engineering-related problems. He has published extensively with over 150 journal articles and two books: Principles of Highway Engineering and Traffic 001Analysis (now in its seventh edition) and Statistical and Econometric Methods for Transportation Data Analysis (now in its third edition). His body of work has been cited over 13,000 in Scopus, over 10,000 times in the Web of Science Core Collection, and over 25,000 times in Google Scholar. Dr. Mannering is currently Editor-in-Chief (and founding Editor) of the Elsevier Science journal Analytic Methods in Accident Research and previous Editor-in-Chief (2003-12) and current Distinguished Editorial Board Member of the Elsevier Science journal Transportation Research Part B – Methodological. He is also the Interim Executive Director of the Center for Urban Transportation Research (CUTR) at the University of South Florida and an Associate Director of the TOMNET University Transportation Center.
Deployable Decentralized Routing Strategies using Envy-Free Incentive Mechanisms for Connected and Autonomous Vehicle Environments
Frederick R. Dickerson Chair and Professor,
School of Civil and Environmental Engineering,
H. Milton Stewart School of Industrial and Systems Engineering
Georgia Institute of Technology
Abstract: Routing strategies using dynamic traffic assignment have been proposed in the literature to optimize system performance. However, challenges have persisted in their deployability and effectiveness due to inherent strong assumptions on traveler behavior and availability of network-level real-time traffic information, and the high computational burden associated with computing network-wide flows in real-time. To address these gaps, this study proposes an incentive-based decentralized routing strategy to nudge the network performance closer to the system optimum in a traffic system with connected and autonomous vehicles (CAVs). The strategy consists of three stages. The first stage incorporates a local route switching dynamical system to approximate the system optimal route flow in a local area based on vehicles’ knowledge of local traffic information. This system is decentralized in the sense that it only updates the local route choices of vehicles in this area to circumvent the high computational burden associated with computing the flows on the entire network. The second stage optimizes the route for each CAV by considering individual heterogeneity in traveler preferences (e.g., the value of time) to maximize the utilities of all travelers in the local area. Constraints are also incorporated to ensure that these routes can achieve the approximated local system optimal flow of the first stage. The third stage leverages an expected envy-free incentive mechanism to ensure that travelers in the local area can accept the optimal routes determined in the second stage. They prove that the incentive mechanism is expected individual-rational and budget-balanced. The study analytically shows that the proposed incentive-based decentralized routing strategy can enhance network performance and user satisfaction in a connected and autonomous traffic environment.
Bio: Srinivas Peeta is the Frederick R. Dickerson Chair and Professor in the School of Civil and Environmental Engineering and the H. Milton Stewart School of Industrial and Systems Engineering at Georgia Institute of Technology. He is also Principal Research Faculty at the Georgia Tech Research Institute. Previously, he was the Jack and Kay Hockema Professor at Purdue University and the Director of the NEXTRANS Center, formerly the U.S. Department of Transportation’s (USDOT’s) Federal Region 5 University Transportation Center. He was also the Associate Director of USDOT’s Center for Connected and Automated Transportation (CCAT). He received his B.Tech., M.S. and Ph.D. degrees from the Indian Institute of Technology (Madras), Caltech and The University of Texas at Austin, respectively. Dr. Peeta’s research interests are multidisciplinary, and broadly span transportation and infrastructure systems.
This seminar took place on April 30, 2021.
Co-Director, Road Ecology Center
University of California, Davis
In US states, mitigation of the spread of COVID-19 has been implemented by cities, counties, and governors’ offices through “shelter-in-place” and “stay-at-home” orders and related actions. The Road Ecology Center carried out three primary types of investigation into the traffic reduction that resulted from these orders and the corresponding “silver linings” that emerged for driver safety, climate change, and nature.
Traffic Safety: Using observations of reported traffic incidents in our real-time “California Highway Incident Processing System” (CHIPS), the Road Ecology Center found a ~50% reduction in injury and non-injury crashes, on state highways and rural roads that resulted from Governor Newsom’s “shelter in place” order, from ~1,000 crashes and ~400 injury/fatal crashes per day to 500 and 200 per day, respectively. These reductions have resulted in a savings to the public of about $40 million/day, or $1 billion since the order went into effect.
Climate Change: In the US, transportation, including personal vehicles, releases about 29% of the greenhouse gas (GHG) per year. We found that estimated emissions had declined by >50% following the various government stay-at-home orders. This puts the US on track to meet its annual goals for GHG reduction under the Paris Climate Accord.
Impacts to High traffic volume is a primary contributor to wildlife-vehicle conflict (WVC) and wildlife mortality on roads. Using traffic and collision data from four US states (California, Idaho, Maine, and Washington), we found a 34% reduction in WVC. This reduction in mortality would potentially equate to 10s of millions fewer vertebrates killed on US roadways during one month of traffic reduction, representing an unintentional conservation action unprecedented in modern times.
Bio: Fraser received his Ph.D. from USC and has three main project areas in transportation ecology: 1) finding out how environmental disruptions (e.g., climate change, pandemics) impact transportation and other systems, 2) studying how traffic noise and light impacts wildlife use of habitat and wildlife crossing structures, and 3) studying the interaction of transportation systems with natural processes. He is the lead organizer for the International Conference on Ecology and Transportation (ICOET) and co-organizer of the Global Congress on Linear Infrastructure and the Environment (inaugural congress in 2021).
This seminar took place on April 16, 2021.
Xuan (Sharon) Di
Associate Professor, Department of Civil Engineering and Engineering Mechanics, Smart Cities Center, Data Science Institute
Columbia University in the City of New York
Abstract: As this era’s biggest game-changer, autonomous vehicles (AV) are expected to exhibit new driving and travel behaviors, thanks to their sensing, communication, and computational capabilities. However, a majority of studies assume AVs are essentially human drivers but react faster, “see” farther, and “know” the road environment better. We believe AVs’ most disruptive characteristic lies in its intelligent goal-seeking and adapting behavior. Building on this understanding, we propose a dynamic game-based control leveraging the notion of mean-field games (MFG). Prof. Di will first introduce how MFG can be applied to the decision-making process of a large number of AVs. To illustrate the potential advantage that AVs may bring to stabilize traffic, she will then introduce a multi-class game where AVs are modeled as intelligent game-players and HVs are modeled using a classical non-equilibrium traffic flow model. Last but not the least, she will talk about how the MFG-based control is generalized to road networks, in which the optimal controls of both velocity and route choice need to be solved for AVs, by resorting to nonlinear complementarity problems.
Bio: Xuan (Sharon) Di is an Associate Professor in the Department of Civil Engineering and Engineering Mechanics at Columbia University in the City of New York since September 2016 and serves on a committee for the Smart Cities Center in the Data Science Institute. Prior to joining Columbia, she was a Postdoctoral Research Fellow at the University of Michigan Transportation Research Institute (UMTRI). She received her Ph.D. degree from the Department of Civil, Environmental, and Geo-Engineering at the University of Minnesota, Twin Cities in 2014. Details about DitecT Lab and Prof. Sharon Di’s research can be found in the following link: https://sharondi-columbia.wixsite.com/ditectlab
This seminar took place on April 9, 2021.
David G. and Diann L. Sant Endowed Professor
Director, NSF ASPIRE ERC
Utah State University
Abstract: Electric vehicles (EVs) offer tremendous opportunity to both reduce the emissions and stabilize and reduce the cost of transportation. However, significant challenges remain, particularly in charging infrastructure. Now is the time, as our nation considers major investments in aging infrastructure, to build for a future designed to support widespread electrification of all vehicle classes. This talk will introduce the ASPIRE ERC and our mission to improve health and quality of life by catalyzing sustainable and equitable electrification in transportation.
Bio: Dr. Regan Zane is Center Director of the NSF Engineering Research Center for Advancing Sustainability through Powered Infrastructure for Roadway Electrification (ASPIRE). He holds the David G. and Diann L. Sant Endowed Professor position at Utah State University in the Department of Electrical and Computer Engineering, where he founded the USU Power Electronics Lab (UPEL), the Electric Vehicle and Roadway (EVR) research facility and test track, and the Battery Limits and Survivability Test (BLAST) lab. He has published approximately 200 peer-reviewed articles, has 28 issued patents, has received international and institutional recognition in research, teaching and innovation, and has raised more than $60 million in research funding to date. His recent research programs span electrified transportation charging systems and infrastructure, from battery, vehicle, and charging systems to grid integration, smart charge management, demand response and distributed energy resources. His programs maintain a strong emphasis on collaboration with academic, government and industry partners to develop and transition innovative technologies into the marketplace.
This seminar took place on Tuesday, April 6, 2021.
Dr. Henry Van
Visiting Professor of Civil Engineering,
The University of Texas at El Paso
Abstract: In this presentation, Dr. Henry Van discussed Cross Border Transportation and Environmental/Health Issues in the El Paso/Juarez Metroplex area, focusing on multifaceted, complex challenges involving very congested traffic with long wait times going from Mexico to the U.S. or vice versa. The border crossing in the El Paso/Juarez area is the same as the other major border crossings in Nogales, San Diego, and Matamoros. Critical transportation problems cause significant financial losses to major manufacturers operating in Mexico transporting products bound for the United States. Commercial and automobile traffic congestion also causes air pollution at the crossings which has become a significant health issue for people living adjacent to these border crossings.
This seminar took place on February 24, 2021.
Johanna Amaya Leal
Department of Supply Chain Management
Iowa State University Ivy College of Business
Even though communities are considered a critical responder after disasters, the subject of community perceptions and trust in response agencies have not received much attention in preparedness research. This study seeks to fill this gap by analyzing how the attitudes and perceptions of individuals in potentially disaster-impacted communities, as well as their socio-economic characteristics, can affect both the roles of trust in emergency response agencies, and risk perception in disaster preparedness.
Usually, organizations developing the necessary preparedness and response plans do not have a clear idea of citizens’ perceptions of the response system, and how these perceptions will/can influence their level of preparedness. Knowing such perceptions would allow communities to engage in the decision of what they need instead of being passive receptors of what is sent to them in case of extreme events. This interaction will positively impact the practice community and will support their effort in building local capacity.
A structural equation modeling approach is used to analyze data from a survey applied to individuals located in towns affected by two different disasters in Colombia. The results suggest that trust in response agencies is mostly influenced by previous experience in disaster situations, education, and income. However, while females have a higher risk perception, they prepare less, even after testing for mediation. Interestingly, for two individuals with the same level of education, the one with a higher income trusts more in the response system. In the same context, for two individuals with the same level of income, the one with higher education trusts less. The seminar will close with a set of recommendations for response agencies, recommendations that take into account the perceptions of the different segments of the population to be served, so that the effectiveness of preparedness efforts and overall level of preparedness of the community increases.
This seminar took place on May 15th, 2020.
View the Building Trust to Enhance Preparedness: An Analysis of Community Perceptions Webinar
Deputy Secretary for Transportation Planning
California State Transportation Agency
The freight transportation system is a complex network that carries everything from cars to petroleum to bananas and more. On ships, airplanes, trains, trucks, and bicycles, cargo often moves across multiple modes before it reaches its final destination. In addition, the rise of e-commerce, trade tariffs, and even COVID-19 are rapidly reshaping the freight industry. This presentation will provide an overview of current freight trends and discussion of California’s role in the national and international freight sector.
This seminar took place on May 8th, 2020.
Professor, Faculty of Transportation Sciences
Czech Technical University
In this presentation, the speaker introduced the concept of smart cities. He shared his experience on several projects in Europe, Asia, and South America that use the smart cities implementation to promote smart healthcare. He also discussed how technologies such as data analytics, smart sensors, wearable devices, connected and automated ambulances, virtual doctors, smart hospital rooms, etc. are being applied to crisis management, clusters identification, contact tracing, transportation of patients, automated testing, diagnosis and monitoring of patients and citizens on quarantine during a pandemic.
Jim Halley, A.A.E., ACE
Florida Department of Transportation,
Office of Policy Planning
Statewide Planning Coordinator
Technology is constantly evolving and changing the way people interact with one another, work, do business, travel, and even how they buy groceries. New and emerging technologies offer the potential for a safer, more efficient transportation system; more connectivity globally and locally; and streamlined business practices. However, increased reliance on technology brings other challenges to the forefront like cybersecurity and data privacy. Transportation partners need to make wise decisions today to prepare for this future.
Natural hazards, cyberattacks, and other events can have significant and unexpected impacts on Florida. Simultaneously, trends such as sea level rise and global economic shifts can lead to progressive challenges. These events and trends can result in unanticipated transportation system disruptions and increasing constraints on infrastructure, impeding access to reliable mobility. The impact on the lives of residents and visitors and the flow of business and trade can be extensive. It is critical to prepare Florida’s transportation system to be adaptive in the face of these events and trends. Planning for resilience leverages our understanding of potential hazards to mitigate risk, make wiser investment decisions, and provide more reliable transportation.
This seminar took place on April 10th, 2020.
Xiaokun (Cara) Wang
Civil and Environmental Engineering
Rensselaer Polytechnic Institute
This presentation talked about the impacts of technologies on freight agent behavior and demand pattern in the near future. The presentation will discuss the special features of the new freight demand, and how to get prepared for these new trends from the perspectives of data acquisition, modeling, and policy making.
This seminar took place on March 27, 2020.
Megan L. Wier
Director, Program on Health, Equity & Sustainability
Co-Chair, San Francisco Vision Zero Task Force
Environmental Health Branch, Population Health Division
San Francisco Department of Public Health
This presentation provided an overview of San Francisco’s Vision Zero policy to eliminate traffic deaths and reduce severe injuries on City Streets. Six years in to San Francisco’s Vision Zero commitment, this presentation will provide insights into what it will take to eliminate traffic deaths, the critical need to elevate equity in traffic safety initiatives, and the key role of public health data and evidence.
This seminar took place on February 14, 2020.
Professor, Department of Family Medicine and Public Health, UC San Diego
Driving behaviors and driving safety involve complex interactions between the driver, their vehicle and the environment. Driving behaviors account for approximately 95% of crashes, but interventions to reduce known risks often don’t reach the target audience. The presenter will discuss strategies employed by the UC San Diego Center for Human and Urban Mobility to improve driving safety.
This seminar took place on February 7, 2020.
Pedestrian and Bicycle Safety Branch Chief
California Department of Transportation
As recommended by California’s Strategic Highway Safety Plan (SHSP), Caltrans is working to develop a pedestrian and bicyclist safety improvement program. This presentation by Rachel Carpenter provided an overview of what has been completed since the program’s inception in 2016 as well as next steps. Specifics behind the below listed efforts were shared.
- the 2016 (Pilot) Pedestrian Collision Monitoring Program,
- the 2018 (Pilot) Bicyclist Collision Monitoring Program,
- the 2020 Pedestrian Collision Monitoring Program,
- pedestrian and bicyclist safety training, and
- modifications to California Manual on Uniform Traffic Control Devices (CA MUTCD) related to pedestrian and bicyclist safety and operations.
This seminar took place on November 22, 2019.
That motorists are a lot less likely to hit someone walking or bicycling if more people walk or bicycle surprised researchers. In contrast, the number of car crashes increases proportionally with the number of cars. The evidence of a prevalence effect implies that injury risk is more than just a matter of physics, and that something occurs with human physiology or psychology. Safety in Numbers likely occurs because humans have difficulty detecting rare items. That injury risk decreases with more walking and biking creates opportunity for implementing public policies for reducing damage to the climate and improving health. This non-linear risk also explains why the recent NTSB recommendation for compulsory bicycle helmet laws could increase injury risk.
This seminar took place on November 15, 2019.
Department of Human Ecology, UC Davis
Background: The Integrated Transport and Health Impacts Model (ITHIM) is a scenario-based risk assessment tool that quantifies the health benefits and harms of physically active travel (walking and cycling), road traffic injuries, and fine particulate air pollution in urban transportation systems.
Methods: Descriptive statistics on travel patterns, physical activity, traffic injuries, and car emissions were derived from statewide travel and health surveys, collision databases, and outputs from regional travel demand and emissions models. The change in disease burden was measured in deaths and disability adjusted life years (DALYs) based on dose–response relationships from meta-analyses and the distributions of physical activity and traffic injuries. Alternative scenarios were measured against baseline travel patterns experienced in each major California region. Alternative scenarios included increases in active travel from baseline to 20 median minutes/person/day, apportioned entirely to walking (“all walk”), cycling (“all cycle”), and or transit-related active travel (“all transit”). The health benefits and greenhouse mitigation of these scenarios were compared to those of the preferred scenarios regional transportation planning agencies. These agencies are mandated to demonstrate greenhouse gas reductions in their transportation plans (“Sustainable Communities Strategies (SB375)”, which emphasize transit expansion to achieve this goal.
Results:The preferred scenarios increased statewide active transport from 41 to 54 min/person/week, which was associated with an annual decrease of 890 deaths and 15,053 DALYs. The ambitious, maximal alternatives increased population mean travel duration to 283 min/person/week for walking, bicycling, or transit and were associated a reduction in deaths and DALYs from 2.5 to 10 times greater than the California preferred scenarios. The alternative with the largest health impact was bicycling, which led to 8,349 fewer annual deaths and 141,597 fewer DALYs, despite an increase in bicyclist injuries. With anticipated population growth by 2040, no alternative achieved decreased carbon emissions, but bicycling had the greatest potential for slowing their growth.
Conclusions: Expansion of transit confers important health benefits through active transport and meets important societal goals for destination accessibility. However, expansion of walking and cycling, independently of transit, can play a larger role in improving population health.
This seminar took place on November 8, 2019.
Collective properties of traffic flow, such as its equilibrium, aggregate dynamics and stability, are determined by attributes of agents (i.e. drivers/vehicles) as well as how the agents interact. Understanding connections between the two is crucial to control and operations, e.g. towards designing mechanisms to make mixed traffic flow of autonomous and human-driven vehicles self-organize and self-stabilize. In this talk, Jia Li presented recent research in this direction. In the first part, Li provided an explicit characterization of equilibriums attainable by heterogeneous traffic flow in multilane settings, where one class of agents are “type-sensitive”, a property that autonomous vehicles may likely be endowed with. In the second part, Li presented simulation evidence along with a heuristic analysis towards explaining spontaneous platoon formation in heterogeneous traffic flow and the role of opportunistic agent behaviors. Finally, Li discussed implications of these results from a control perspective.
This seminar took place on November 1, 2019.
There are tremendous opportunities in Hillsborough County at this time. We can create a safe, sustainable transportation network and build the kind of vibrant, walkable places that bring opportunity, economic development, and support a higher quality of life for our residents. Commissioner Kemp is looking forward to joining other women leaders in transportation in Hillsborough County to have a conversation about how they can work together to accomplish these goals. She will be joined by Jean Duncan, P.E. Director of Transportation and Stormwater Services for the City of Tampa, Cassandra Borchers, AICP, Chief Development Officer of PSTA, and Beth Alden, AICP, Executive Director of Hillsborough County MPO.
This seminar took place on April 24, 2019.
AICP, Executive Director
Hillsborough Metropolitan Planning Organization for Transportation
Nationally-renowned transit planner Jarrett Walker has said, “The discussion of equity in transportation … is at its best a study of the equal distribution of freedom.” Ms. Alden will discuss the intersection of access, public health, safety, and multimodal transportation investments in Tampa and Hillsborough County, reflecting on the use of tools such as scenario planning and performance-based programming to collaboratively reshape priorities in our community.
This seminar took place on March 28, 2019.
Lawrence D. Frank
Ph.D., AICP, CIP, ASLA
Professor and Bombardier Chair in Sustainable Transportation and Health
University of British Columbia
President, Urban Design 4 Health, Inc.
New evidence linking built and natural environment features with physical activity, obesity, diabetes, cardiovascular disease, stress, and sense of community will be presented. These finding are based on large scale health surveillance databases (40,000-50000 N) with address information spatially linked with detailed measures of regional transportation accessibility, walkability metrics, and green space. Results have been integrated into decision-support scenario planning tools (California and National Public Health Assessment Models) designed to predict health impacts of contrasting land use and transportation investment proposals at the neighborhood, corridor, and regional scale.
This seminar took place on March 25, 2019.
Florida’s Strategic Intermodal System (SIS) represents the state’s largest and most significant transportation facilities including airports, spaceports, seaports, rail corridors, passenger terminals, transit, waterways, and highways. The SIS serves as the primary avenue for implementing Florida’s long-range transportation vision and SIS facilities receive the highest priority for transportation capacity improvements. Florida Department of Transportation (FDOT) Systems Implementation Office Manager Huiwei Shen, SIS Planning Manager Chris Edmonston, and SIS Administrator Jennifer King shared how the SIS plans for multimodal facilities.
This seminar took place on March 6, 2019.