Travel Behavior and Transport Systems Modeling
What about the people who use transportation? A glorified new technology can fall flat on its face if it doesn't meet people's needs, and a brilliant policy for reducing congestion can fail if travelers are marching to a different tune. The Institute's research into travel behavior and transport systems modeling is breaking new ground in several important areas. ITS-Davis has one of the largest concentrations of travel behavior experts in the world; their diverse disciplines include anthropology, psychology, marketing research, economics, statistics, geography, and civil engineering.
Visit Telecom and Travel Behavior Research Program
Research
Self Selection: Walking, Driving, and Residential Choice
Applying System Optimization Theory to Diverse Projects
Integrated Construction Zone Traffic Management
Self Selection: Walking, Driving, and Residential Choice
To some extent, our surroundings affect how much and how we travel. If we can work, play and shop within walking distance of our homes, for instance, we may not drive as much. But does the built environment itself influence us? Or do we choose built environments that suit us? And if planners changed neighborhood design, would people change their travel behavior?
These are the key questions underlying research that seeks to provide meaningful input into land use planning decisions. Professors Patricia Mokhtarian and Susan Handy find that people self-select; their preferences affect their activity level and choice of neighborhood. But they also find that the built environment affects walking behavior, even after accounting for preferences.
“If people who aren’t predisposed to walking move into a neighborhood where many activities are within walking distance, they might walk more, simply because it’s convenient. And they might even start to like walking more over time, whether or not they are conscious of these changes,” says Handy.
Understanding these dynamics is important because they relate to land use policies intended to reduce travel, Mokhtarian explains.
“If car-lovers end up in a walkable neighborhood for the wrong reasons - let’s say they were drawn in by financial incentives used as a policy instrument - their travel behavior probably won’t match that of those who chose the neighborhood because it was conducive to walking, and thus the policy will not be as successful as expected.”
Handy and Mokhtarian focus much of their research on people’s travel choices. Mokhtarian is an established expert on commuting and telecommuting, and Handy examines the link between built environment and physical activity and health.
PI: Susan Handy, Patricia Mokhtarian
Students: Xinyu Cao, Kristin Lovejoy
Funding: Caltrans, University of California Transportation Center, Robert Wood Johnson Foundation
Symbolic Meaning of Vehicles
In consumer societies, what we buy says much about us. It is as much about whom we want to become and how we wish to be seen as it is about form, feature, and function. But research on the hybrid car market has largely ignored what hybrids mean and examined only functionality and economics.
Researchers Ken Kurani and Tom Turrentine with grad student Rusty Heffner wanted to know who is buying hybrid cars and why. After 50 comprehensive interviews - and more to come - with hybrid buyers from across Northern California, they have confirmed that people buy hybrids for reasons far more complex than saving money.
“For most households a hybrid vehicle is a symbol for their identity,” says Heffner.
As we might expect, that identity includes an environmental ethic. But it also symbolizes a smart financial decision, says Kurani. “Households of a certain age see hybrids as a symbol of frugality. It’s an ethical view, right versus wrong.”
Ironically, despite the central role of fuel economy in the design and marketing of hybrid vehicles, the researchers found that most households do not calculate costs and savings to make a purchase. “The idea of saving money was an important part of their purchase decision but they did no financial analysis,” says Turrentine.
Next, researchers plan to look for the meanings of fuel cell vehicles. “We’re curious because virtually no consumer has hands-on experience with them,” says Heffner. “But some of our households are telling us: ‘I’m going to buy one when they come out.’”
PI: Ken Kurani, Tom Turrentine
Students: Rusty Heffner
Funding: Toyota Motor Sales, U.S.A.
Applying System Optimization Theory to Diverse Projects
Professor Yueyue Fan likes to look at the big picture. She applies her mathematics training - specifically the study of uncertainty, dynamics and system optimization - to research topics ranging from highway bridges to hydrogen infrastructure.
“It’s all in the approach. As long as the work involves decision making in an uncertain environment, I can apply my skills.”
Fan has worked with the Pacific Earthquake Engineering Research Center on a three-year project to evaluate the seismic risk of 3,000 bridges in the nine-county San Francisco Bay Area and allocate limited retrofitting funds to those most in need. In the past, she explains, engineers analyzed each bridge or overpass based on traffic load, age, and other factors. Now, they’re taking a system-wide approach. They examine the entire bridge and highway network and factor in hundreds of potential uncertainties such as driver behavior as they consider how roads and bridges might be affected by an earthquake. Fan helps planners model pre-disaster prevention and post-disaster recovery processes.
“In addition to providing a sophisticated mathematical model, I hope my research can provide Caltrans with solid recommendations and support effective decision making.”
Fan also has helped Hydrogen Pathways researchers model the optimal location of hydrogen production and delivery facilities. In the case of biomass conversion plant locations, she asks, “Do we locate them near the rice fields where the fuel is produced, or near cities where the fuel will be used? And do we deliver the fuel by pipeline or truck? All these questions have to be answered together and factored into a system. We can’t separate them. It’s an integrated system to study.”
PI: Yueyue Fan
Students: Changzhen Liu, R.P. Naga (Seismic Risk Analysis for Highway Systems)
Nathan Parker, David Lin (Hydrogen Pathways)
Funding: National Science Foundation, Caltrans, Hydrogen Pathways
Integrated Construction Zone Traffic Management
The next time you’re stuck in traffic in a highway construction zone, perhaps you can find solace in knowing that Professor H. Michael Zhang is trying to ease your frustration. Zhang has developed a computer model that helps Caltrans analyze construction zone problems and design strategies for easing congestion.
Zhang has studied the ebb and flow of traffic from data provided in recent years by traffic sensors along major construction projects on interstate highways, I-15, I-710 and I-80 in Southern and Northern California. His work integrates engineering factors such as lane capacity and vehicle flow with human factors such as drivers slowing down in construction zones.
Zhang is well-known for his work in modeling traffic flow. His research examining the linkage between driver behavior and traffic flow dynamics has deepened our understanding of the transition that occurs when freeway traffic changes from orderly flow to chaos.
His current construction zone modeling helps Caltrans develop a work zone plan that considers when and how many lanes to close, the costs and impacts of detours on other routes, traffic metering and advance signage to encourage drivers to choose alternative routes during prescribed times.
“We’re trying to develop methods, assess the situation, and optimize the decisions for dealing with each situation.” It is a more comprehensive, systematic approach to construction zone traffic management, and it matches Zhang’s research interests in engineering highways to meet travel needs while reducing congestion and minimizing environmental impact.
“With better tools and methods we can help Caltrans minimize costs by choosing the best construction schedule. We can also make drivers happier with better and more efficient alternative routes that reduce accidents and improve safety.”
And if Zhang’s work reduces road rage, then all of society is served.
PI:H. Michael Zhang
Students: Wei Shen, Yu Nie
Funding: Caltrans