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changing.jpgThough no one can predict the future, thinking about how today’s changes may shape the future of transportation in our country is more important now than ever before.

“It’s critical that we understand the significance of things that are taking place and prepare for what may come,” said former Utah Department of Transportation CEO John Njord in the opening session of the 25th Annual CTS Transportation Research Conference. “For us to be relevant in the transportation business, at a minimum we have to be adaptable to change, and ideally we want to be leading change in the transportation industry.”

In his current position at Tom Warne and Associates, Njord has gained an in-depth understanding of the trends affecting the future of transportation in the United States while spearheading the Transportation Research Board’s “Foresight” project—part of the organization’s forward-looking NCHRP Report 750 Series. The project addresses a wide range of topics, including: What if the oil-fueled auto era ends and revenue from gas taxes dries up? What if engineering practices must be upgraded to ensure resiliency to natural disasters as global warming continues? What if technology such as self-driving cars eliminates or reduces the need for human drivers? What if tomorrow’s economy requires radically different freight patterns?

Perhaps most significantly, the project explores the possibility that Americans are losing their appetite for driving. Vehicle-miles traveled (VMT) per capita been dropping since 2004, without any signs of recovery. "It’s impossible to know whether that number will start growing again, stay flat, or continue to drop,” Njord said.

Other trends make the future outlook equally complex. In 50 years the United States will likely be home to 100 million more people, so even if VMT per person stays flat or declines, it’s likely total VMT will be larger than it is today. The population is also aging: by 2030, 20 percent of the population will be over 65 and will likely drive less. In addition, Millenials are staying home longer and waiting until later in life to get married and have children—all of which affects their travel behavior.

To help transportation planners consider all possible futures, the Foresight project encourages the use of multiple-scenario planning. “We need to begin considering all the possible scenarios and generating plans that are independent and distinct from one another,” Njord advised. “The act of thinking about these things is fundamentally important, because the shift that is now taking place means we’re going to have to do things much differently in the next 50 years than what we’ve done in the past 50 years.”

Following Njord's presentation, a panel of experts discussed how the the Foresight project could relate to what’s happening in the Twin Cities region. An article summarizing their comments is available in the July issue of Catalyst.
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Despite more similar roles at work and home than ever before, U.S. men and women continue to have different travel behavior. Historically, employed men have spent more time traveling to work and less time on household and family support trips than women.

While this difference is well-documented, explanations for the difference vary widely: some theories say it’s due to biologically driven differences in gender, while others attribute it to socially constructed gender roles or to gendered structural contexts such as labor market segregation and economic inequality.

While much research has examined these theories, few studies have tested their validity based on evidence—which prompted U of M researchers to examine the theories more deeply in attempt to effectively address gender equity issues in transportation policy.

The researchers set out to test the competing theories by analyzing publicly available data from the American Time Use Survey (ATUS) in various ways across groups of workers with different types of family structures.

First, they tested the theory that travel behavior differences were based on biologically driven gender differences. “If this theory was true, travel differences between men and women could be applied across all population groups regardless of family structure, but this was not the case,” Fan explains. “We found that single female workers and single male workers exhibit no significant difference in travel behavior.”

Next, the team studied the impact of gendered structural contexts, such as women’s greater presence in pink-collar occupations and significantly lower earnings. The team found moderate support for this theory. “These factors are associated with shorter work travel time among some—but not all—family structures,” Fan says.

Researchers did find strong support, however, for the theory that socially constructed gender roles explain travel behavior differences. “We discovered that while marriage alone doesn’t differentiate travel behavior between men and women, parenthood does have a significant impact,” Fan says. “Interestingly, we found that even being the sole breadwinner does not insulate mothers from socially constructed gender roles—female breadwinners in married single-worker households with children have shorter work commutes and more household support travel than male breadwinners in the same family structure.”

According to the researchers, these findings have important implications. First, policies to minimize auto travel (for environmental purposes, for example) may be unfair to women who wish to reach more job possibilities through longer commutes. In addition, the findings highlight the importance of incorporating parenthood as a prime variable in understanding the gender and mobility connection.

Finally, this research provides insights on how future growth or decline in specific family structures may shape travel demand. “As childless households continue to grow in relation to households with children, it’s possible that fewer female workers will be confined by short work commutes and may choose to spend more time commuting to more desirable jobs, placing new demands on the transportation system,” Fan says.

The research was funded in part by a Minnesota Population Center Program Development Grant.

Exploring Nice Ride job accessibility and station choice

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Although bike share systems are becoming more popular across the United States, little is known about how people make decisions when integrating these systems into their daily travel.

In a study funded by CTS, researchers from the U of M’s civil engineering department investigated how people use the Nice Ride bike share system in Minneapolis and St. Paul. The researchers examined how Nice Ride affects accessibility to jobs and developed a model to predict station choice.

In the first part of the study, the researchers created maps showing accessibility to jobs by census block for both Nice Ride and walking—as well as the difference between the two—at time thresholds ranging from 5 to 55 minutes.

Overall, in blocks with both Nice Ride and walking job accessibility, Nice Ride provides access to 0.5 to 3.21 times as many jobs as walking.

By comparing Nice Ride to walking, the study demonstrated that walking can successfully be used as a baseline to show how a bike share system improves job accessibility. The results also pinpointed when and where Nice Ride had the strongest accessibility advantage over walking.

“This type of information can be used by bike share system planners to identify where new stations could be built to maximize their impact on job accessibility,” says grad student Jessica Schoner, a member of the research team.

In addition, the team developed a theoretical model for bike share station choice. The model considers users’ choice of a station based on their preference 
for the amount of time spent walking, deviation from the shortest path (the closest station may not be in the direct path of the person’s destination), and station amenities and neighborhood characteristics.

Findings show that people generally prefer to use stations that don’t require long detours to reach, but a station’s surroundings also play an important role. Results also indicate that commuters value shorter trips and tend to choose stations that minimize overall travel time.

According to Schoner, understanding people’s station preference can help provide guidance to planners that want to expand or optimize a bike share system.

Read the full article in the January issue of Catalyst.

Why are Twin Citians taking fewer trips?

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By David Levinson

The latest summary of the Twin Cities Travel Behavior Inventory is out, and it says the total number of trips in 2011 is lower than in 2001.

This is consistent with a lot of evidence we have been seeing from various sources on "Peak Travel." Nationally, passenger miles on highways traveled today is lower than 1999, and miles per capita lower still. This is in stark contrast with the trend from 1900 to 2000, when vehicle miles traveled increased almost every year, with a few exceptions due to economic downturns or energy shocks. Why might this be? There are a number of hypotheses:

  • Employment - If fewer people are working, fewer people are traveling for work, and fewer discretionary trips are made by both workers (nervous about spending money) and the unemployed (who have little or no money to spend). Unemployment increased sharply beginning in 2008, and though it has declined, employment participation are still much lower (hovering around 58.6% of the population, down from 62.7% for the period before the recession). Demographics are part of this, and many people have just dropped out of the labor market, as their skills have been devalued by the economy, and either chosen early retirement (if near retirement) or deferred entry into the workforce (if young). The rise in female labor force participation from the 1950s through the 1990s has run its course, as labor force participation is roughly at parity by gender.
  • Gas prices - The price of fuel increased sharply in the run-up to the Great Recession - and this certainly discouraged car travel. Interestingly, it also reduced car crashes by more than the reduction in VMT, which we attribute to worse than average drivers (especially the young) being more likely to be priced off the road.
  • Changes in driver license regulations - It is harder for young people to get drivers licenses, and less valuable since they now need more supervision. More defer licensure and auto acquisition.
  • Social networking - It is now easier to virtually communicate with friends, in real-time and asynchronously, whereever you are, so it may be less necessary to actually visit them. Time online just continues to rise, especially mobile.
  • At home work - Telecommuting continues to rise, more as a complement to office work than a substitute (check your email when you get up, check your email before bed), but even as the occasional substitute, so I can work from home either sometimes or regularly.
  • At home shopping - The rise of online retailing allows us to substitute delivery for fetching, and reduce the amount of shopping trips.
  • Kids today just don't like cars - The culture just may be different, and the desire for mobility, especially auto-mobility has dropped, as kids would prefer to spend their disposable income on the latest internet-connected gadget.

There may certainly be other explanations as well. No one of these explanations is the whole story, and some are certainly more likely than others, but they all work in the direction of reducing auto travel. Importantly, travel by other modes has not made up for the large drop in car use. While transit, e.g., is up nationally due to the large investments in rail lines, that 20% increase in transit use in the decade is a little more than 1% of the 20% drop in passenger miles by motor vehicles.

Colleagues (Jason Cao, Yingling Fan, Michael Iacono, Greg Lindsey) and I have a study currently underway, Travel Behavior Over Time, with support from the Minnesota Department of Transportation and the Metropolitan Council to examine not just the top-line number, but what goes on underneath. We plan to determine the factors that explain travel demand and see if they are the same as in previous decades. We hope to understand whether the factors are the same, but the conditions are different, or whether underlying travel preferences have changed.

David Levinson is a Professor in the Department of Civil Engineering at the University of Minnesota, and the Director of the Networks, Economics, and Urban Systems research group. He holds the Richard P. Braun/CTS Chair in Transportation. He is principal investigator of the University's new Accessibility Observatory, which evaluates transportation systems in terms of accessibility, or, the ability to get to desired locations. He has authored or edited several books and numerous peer-reviewed articles, and is the editor of the Journal of Transport and Land Use. He blogs at transportationist.org.

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