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Investigating air pollution risks for pedestrians and cyclists

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Although active forms of travel such as bicycling and walking provide many health benefits, they may also increase travelers' exposure to air pollution—especially in urban areas, where the air pollutants that drive health concerns are typically at their highest concentrations.


To investigate the exposure of cyclists and pedestrians to these pollutants in the City of Minneapolis, researchers from the U of M's Department of Civil Engineering (CE) are developing a block-by-block analysis of air pollution levels. In a presentation at the 24th Annual CTS Transportation Research Conference on May 23, graduate student Steve Hankey explained how this information could ultimately be used to identify high-risk locations and shape decisions about new nonmotorized infrastructure. The project is funded by the U of M's College of Science and Engineering and the Humphrey School of Public Affairs.

In summer 2012, Hankey collected particulate air pollution measurements in Minneapolis using an instrumented bicycle trailer as he rode around the city on three 20-mile routes. Each route captured different levels of traffic and air pollution, Hankey said, and included a wide variety of road types and surrounding land uses.

Preliminary findings suggest that air pollution levels are 1.5 to 2.3 times higher in on-road locations than on off-street trails and 2 to 3.5 times higher in the morning than in the afternoon. Results also indicate that air pollution concentrations are associated with street classification and traffic intensity.


Arterial streets with the most traffic had the highest air pollution levels, with lower concentrations on local roads and off-street trails. "If you can choose to bike on a local road that's a block or two off an arterial collector, that would make a big difference in your exposure," Hankey said.

The project's next step is to tie the existing mobile measures to land-use variables so the data can be extrapolated to other parts of the city, Hankey said. The resulting model will show air pollution levels for every block in Minneapolis.

The researchers plan to use this model in conjunction with bicycle and pedestrian traffic volume data being collected by a team of researchers from the Humphrey School led by Professor Greg Lindsey. The combined model could be used to identify "hot spots" with both large volumes of pedestrian or bicycle traffic and high levels of air pollution, Hankey said.

This information could be used to develop mitigation strategies in high-risk locations and to make recommendations for the development of future infrastructure in areas with lower pollution concentrations.

"We'll also release the air pollution estimates so people can integrate them into existing tools," Hankey said. "For example, in [the bike route tool] Cyclopath, a user could choose a low air pollution route instead of the fastest route or shortest route."

Reprinted from CTS Catalyst, July 2013.

A new wave of technological change in transportation

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From social media to intelligent transportation systems, technology is rapidly changing the transportation landscape to create "new mobility"—a trend that was the focus of Elizabeth Deakin's luncheon presentation at the 24th Annual CTS Transportation Research Conference.


"New mobility isn't just about moving people—it is integrating new technologies and new ways of delivering sustainable transportation services that gives people access to more goods, services, and opportunities," said Deakin, a professor of city and regional planning at the University of California, Berkeley.

A number of transportation trends fall under the definition of new mobility, Deakin said, including car sharing, bike sharing, carpooling, smart transit, smart cars, and smart highways. Importantly, while these new mobility approaches have typically been used in urban areas, many of the ideas—such as car sharing, ride sharing, and bike sharing—can work in rural settings as well.

The reasons for the growing interest in new mobility are diverse. From a government perspective, it can enhance mobility, save money, reduce congestion, decrease environmental impacts, and improve public health. For users, it creates more transportation options, greater flexibility and affordability, and health benefits while promoting environmental and social responsibility.


One of the driving forces behind the shift toward new mobility appears to be Millennials—the generation of 20-somethings that grew up building online communities through social media sites such as Facebook and Twitter. Today, they are using social and mobile technology to build communities in the real world—and transportation is no exception. Dynamic ride sharing is just one example: commuters use their smartphones or tablets to request or offer a ride on the fly; the device's GPS navigation capability is used to arrange the ride's pick-up and drop-off points. "We've also seen an increasing interest in services where users create a network of friends and offer dynamic ride sharing only to that known group," Deakin said.

Another growing carpooling trend is "casual carpooling," in which drivers pick up passengers from established locations to share a ride without an ongoing arrangement. "It's sort of like hitchhiking but more organized," Deakin said. "The benefit is that adding riders qualifies the car for HOV lanes and saves everyone significant time off their commute."

New mobility may also change our transportation system's future. Transit will likely get a boost from new technologies that improve travel times with exclusive lanes, signal preemption, off-board fare payment, and more. On the highway, the use of sensors to monitor traffic and control flows will help the whole system run more smoothly; vehicle-highway communication and vehicle sensors will improve safety.

According to Deakin, the move toward new mobility may be a way to bring together diverse views of transportation's future. "One vision of the future is cities that are transit-oriented, while others envision a new world of vehicles that basically drive themselves. New mobility may be the way we integrate those two visions by matching them to the local context to create a transportation system that goes beyond a one-size-fits-all approach."

Reprinted from CTS Catalyst, July 2013.


In a continuing effort to better understand nonmotorized traffic patterns in Minnesota, researchers from the Humphrey School of Public Affairs have partnered with the Minnesota Department of Transportation (MnDOT) to develop guidelines and analyze information collected in bicycle and pedestrian traffic counts throughout the state.
The research team, led by Professor Greg Lindsey, aims to develop consistent methods for monitoring and assessing bicycle and pedestrian traffic that can be used in both permanent, automated traffic counts and short-term manual counts. The goal is to provide evidence for decision making that Minnesota cities have historically lacked, Lindsey says. "We'll have practical, useful information about bike and pedestrian traffic that can help local jurisdictions as they plan and invest in infrastructure," he says.

As part of the 18-month project, the research team created a set of tools and methods for short-duration manual counts of nonmotorized traffic, held training workshops, and organized a statewide counting effort involving 43 Minnesota municipalities last fall. The overall response was positive, Lindsey says, and some communities are already using their collected data to submit grant proposals for projects related to nonmotorized traffic.

In addition, Lindsey and his team have examined traffic information from six permanent 37_250px.jpgcounters on Minneapolis trails. The continuous counts collected at these locations help the researchers understand traffic patterns and the factors that affect them, Lindsey says. For example, the team found that bike and pedestrian traffic vary by trail type, time of day, day of week, and season.

"Once we know the patterns at permanent sites, we can develop factors that help us expand short-term counts from other locations with similar conditions," Lindsey says. The factors could be used to estimate anything from total daily traffic to annual traffic, as long as the short-term count location is similar to an existing model.

Based on the overall results of the study, the research team developed recommendations for MnDOT. These include continuing to coordinate statewide short-term field counts, demonstrating the feasibility of automated counting technologies, and beginning to integrate nonmotorized and vehicular traffic databases.

Based on these recommendations, MnDOT is moving forward with a new project that will collect more short- and long-duration counts throughout Minnesota, says Lisa Austin, ABC Ramps coordinator at MnDOT. The next phase of work aims to collect counts for pedestrians on sidewalks, bicyclists on shoulders and in bike lanes, and pedestrians and bicyclists on multiuse trails. MnDOT plans to install more permanent, automated counters in suburban and midsize cities and to conduct additional manual counts in smaller cities around the state, Austin says.

"We're really excited that this bike and pedestrian counting project is moving into wider implementation," Austin says. "This next phase will help us see which automated counting technologies work well and make recommendations for moving forward on a broader scale."

Reprinted from the CTS Catalyst, May 2013.

Video on U of M transportation research highlights

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U of M transportation research highlights during 2012-2013 include a smartphone app for visually impaired pedestrians, pedestrian and bicyclist safety in roundabouts, methods for counting bike and pedestrian traffic on trails for better urban planning, and filtering phosphorous from storm water.



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