All posts by Christine Anderson

Policy and Planning, Research

Study recommends strategies for reducing transportation disparities

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Transportation contributes to many broad societal outcomes, such as employment, wealth, and health. Some Minnesotans, however, are underserved by current systems and face disparities and barriers in reaching their destinations. According to new research from the U of M, efforts to improve transportation equity need to focus on societal inequities—such as racial segregation and auto dependency—as well as the transportation barriers that affect specific communities and population groups.

“This study is an important early step in MnDOT’s Advancing Transportation Equity Initiative to understand how the transportation system, services, and decision-making processes help or hinder people in underserved and underrepresented communities in Minnesota,” says Hally Turner, planning program coordinator with MnDOT’s Office of Transportation System Management.

The underserved and underrepresented include low-income neighborhoods, communities of color, indigenous communities, rural residents, older adults, people with disabilities, women and youth, and people with limited car access.

Gina Baas, CTS associate director, engagement and education, was the principal investigator. The research team included co-investigator Yingling Fan (professor) and Leoma Van Dort (research assistant) of the Humphrey School of Public Affairs and co-investigator Andrew Guthrie (former Humphrey School research fellow, now assistant professor with the University of Memphis). MnDOT funded the study.

The researchers began by examining current research and practice in the field of transportation equity. They found that societal-level structural inequities cause specific population groups to face disproportionate transportation barriers.

“Some of these structural inequities, such as racialized spatial segregation in metropolitan areas and auto-dependent development patterns, are built into the very fabric of our communities,” Fan says. “The user-pay principle that governs the current transportation finance system is viewed as another inequity, as it does not take into account users’ ability to pay.”

Building on their review, the researchers then explored 24 programs from across the United States that aim to improve transportation equity. The result was structured, generalizable knowledge about the current state of the practice.

Stakeholder engagement was an integral component of the study. “We received key guidance from MnDOT, other public-sector agencies, and external community partners with expertise in addressing disparities and inequities,” Baas says. “We also engaged community members at a community event in Minneapolis to seek direct input from attendees about the day-to-day transportation challenges they face.”

Based on their findings, the research team developed recommendations for MnDOT and other transportation partners to consider in advancing transportation equity. The recommendations, categorized under six overarching themes (see below), address both societal inequities and the inequities of the transportation system itself. The report identifies which underserved and underrepresented populations are most likely to benefit from each recommendation, along with what modes of transportation each recommendation affects.

“The study lays a foundation for MnDOT to work with transportation partners to meaningfully reduce disparities,” Turner says.

The final report—Advancing Transportation Equity: Research and Practice—and a four-page policy brief are available on the MnDOT website.

Six themes for addressing transportation equity

  • Engagement processes. Design engagement processes that facilitate community leadership and the inclusive participation of traditionally underserved and underrepresented communities, where community members drive conversations around their transportation needs and strategies for implementing solutions.
  • Increased opportunities. Initiate programs and policies that increase access to social and economic opportunities, such as jobs, affordable housing, healthy food, education, health care, and recreation, particularly for underserved and underrepresented communities.
  • Transportation for sustainability and health. Create policies and programs that support active transportation and provide safe, smart, and affordable transportation alternatives that minimize automobile dependency to create healthier, more sustainable communities.
  • Equity spending. Integrate equity promotion as a standardized practice at the agency and program level, particularly in prioritizing spending across the system and distributing infrastructure projects.
  • Collaboration and coordination. Collaborate and coordinate across transportation and non-transportation agencies, institutions, and organizations—including academic institutions—to advance equity.
  • Evaluation metrics. Incorporate both quantitative and qualitative metrics for evaluating transportation programs and projects as well as their impacts on underserved and underrepresented populations
Research, Traffic and Safety

Smartphone prototype app warns drivers of high-risk curves

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Lane-departure crashes on curves make up a significant portion of fatal crashes on rural Minnesota roads. To improve safety, solutions are needed to help drivers identify upcoming curves and inform them of a safe speed for navigating the curve.

“Traditionally there are two ways to do this: with either static signage or with dynamic warning signs,” says Brian Davis, a research fellow in the U of M’s Department of Mechanical Engineering. “However, while signing curves can help, static signage is often disregarded by drivers, and it is not required for roads with low average daily traffic. Dynamic speed signs are very costly, which can be difficult to justify, especially for rural roads with low traffic volumes.”

In a recent project led by Davis on behalf of MnDOT and the Minnesota Local Road Research Board, researchers developed a method of achieving dynamic curve warnings while avoiding costly infrastructure-based solutions. To do so, they used in-vehicle technology to display dynamic curve-speed warnings to the driver based on the driver’s real-time behavior and position relative to the curve. The system uses a smartphone app located in the vehicle to provide the driver with visual and auditory warnings when approaching a potentially hazardous curve at an unsafe speed.

“Highway curves [make up] 19 percent of the total mileage of the paved St. Louis County highway system, yet these curves account for 47 percent of all severe road departure crashes,” says Victor Lund, traffic engineer with St. Louis County. “In-vehicle warnings will be a critical strategy to reduce these crashes.”

To begin their study, researchers designed and tested prototype visual and auditory warning designs to ensure they were non-distracting and effective. This portion of the study included decisions about the best way to visually display the warnings and how and when audio messages should be used. “To create the optimal user experience, we looked at everything from how to order the audio information and when the message should play to the best length for the warning message,” says Nichole Morris, director of the U’s HumanFIRST Lab and co-investigator of the study.

Next, a controlled field test was conducted to determine whether the system helped reduce curve speeds, pinpoint the best timing for the warnings in relation to the curves, and gather user feedback about the system’s usefulness and trustworthiness. The study was conducted with 24 drivers using the test track at the Minnesota Highway Safety and Research Center in St. Cloud, Minnesota. The selected course allowed drivers to get up to highway speeds and then travel through curves of different radii, enabling researchers to learn how sensitive drivers are to the position of the warnings.

Based on the study results, the system shows both feasibility and promise. “Our in-vehicle dynamic curve warning system was well-liked and trusted by the participants,” Davis says. “We saw an 8 to 10 percent decrease in curve speed when participants were using the system.”

The project was funded by MnDOT and the Minnesota Local Road Research Board.

Research

New video traces progress of accessibility research

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CTS has been celebrating its 30th anniversary this year with a look back at significant milestones. One of our goals for the anniversary was to show how research progresses over time to lead to new knowledge.

In February we shared videos that trace the path of progress in two of our key research areas: traffic operations and pavement design. Today, at our 28th Annual Transportation Research Conference, we debuted a video about another important research topic: accessibility metrics.

In the new video, Andrew Owen, the director of the U’s Accessibility Observatory, explains how accessibility looks at the end-to-end purpose of transportation: fulfilling people’s need to reach destinations. “The Observatory is pushing the envelope and staying ahead of research into what new types of metrics are possible,” he says.

The Observatory builds on tools and expertise developed in two previous University research studies: the Transportation and Regional Growth Study (1998–2003) and the Access to Destinations study (2004–2012).

Research

Register for the annual CTS Research Conference

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Join us at the 28th Annual CTS Research Conference to hear about new learning, emerging ideas, and the latest innovations in transportation. This year’s event is scheduled for November 2 at The Commons Hotel in Minneapolis.

Attendees will learn about research findings, implementation efforts, and engagement activities related to a variety of transportation topics. This year’s keynote presentations feature:

  • Joung Lee, policy director at AASHTO, on how we pay for transportation infrastructure
  • Joshua Schank, chief innovation officer at LA Metro, on policy innovation at his agency

To browse the full program or register for attend, visit the CTS website.

Environment, Maintenance Operations, Research

New recommendations aim to help roadside turfgrass thrive

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Keeping Minnesota’s roadsides green is about more than just aesthetics—healthy turfgrass can improve water quality, reduce erosion and road noise, and provide animal habitat. However, harsh conditions such as heat, drought, and salt use can make it difficult for roadside turfgrass to thrive.

In 2014, as part of a study funded by the Minnesota Local Road Research Board (LRRB), researchers in the University of Minnesota’s Department of Horticultural Science identified a new salt-tolerant turfgrass mixture that could be used on Minnesota roadsides. But, when MnDOT began using the mixture, called MNST-12, the agency experienced a series of installation failures.

Now, led by Professor Eric Watkins, the research team has identified new best management practices for installing and establishing this type of salt-tolerant turfgrass.  The study, funded by the LRRB, specifically focused on watering practices, soil amendments, and planting date for both seed and sod.

“Newer improved seed or sod mixes like MNST-12 may have differing requirements for successful establishment compared to other species or cultivars that contractors and other turf professionals are more familiar with,” Watkins says. “Since all of these management practices are prescribed—or not prescribed—in the MnDOT specifications, generating data that can inform future specifications is a valuable outcome of this work.”

The study, which was conducted over several years, included experiments on how water should be applied to new MNST-12 turfgrass installations, the use of soil amendments at the time of establishment, and the effect of the seeding or sodding date on the success of a new planting.

Researchers tested turfgrass watering requirements using an automated rain-out shelter. Photo: Matt Cavanaugh

Based on their findings, the researchers recommend these changes to MnDOT specifications:

  • No soil amendments are necessary, but adequate seedbed preparation is important.
  • Seeding is preferred to sodding between August 15 and September 15.
  • Sodding can be permitted throughout the year, but only if the installer is able to supply frequent irrigation.
  • When watering in sod, attention should be given to the species being used and local rates of evapotranspiration (evaporation from both the soil and plant leaves). Sod installers can anticipate using between 100,000 and 170,000 gallons of water per acre to ensure a successful establishment.
  • Sod can be mowed as soon as sufficient root growth prevents an operator from manually pulling up pieces by hand, but it should not be mowed if wilting from heat or drought.

Currently, the researchers are using the results of this project to develop methods for educating and training stakeholders, including turfgrass installers, on these best management practices. They are also developing systems that could be used by installers in the field to help maximize the success rate of turfgrass installations.

“These best management practices can help limit installation failures and reduce maintenance inputs for future installations, providing both an economic and environmental benefit,” Watkins says.

“The knowledge and improved specifications we gained through this research will allow us to make our contractors more successful, which makes MnDOT successful,” says Dwayne Stenlund, MnDOT erosion control specialist. Because local agencies often rely on these MnDOT specifications as a guide for their projects, they will also benefit from the improved practices.

Stenlund also says the new specifications—especially those related to watering requirements—could allow for a clearer understanding of the true cost and value of turfgrass installation and maintenance work, which could ultimately improve the accuracy of the project bidding process.

In another project, the research team is exploring other turfgrass stresses, such as ice cover and heat. They are also testing additional turfgrass species and mixtures in an effort to continue improving MnDOT specifications for roadside turfgrass installations.

Traffic and Safety

Gauging safety of heavy vehicles on older concrete bridges

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Bridges built using prestressed concrete girders are among the most common in Minnesota and throughout the U.S. because of their good performance, lower initial material costs, and relatively low ongoing maintenance costs. However, the federal requirements for these bridges have changed considerably over the years. As a result, bridges built to older specifications may score poorly when subjected to new bridge rating standards even though they are actually in good condition.

“One area in which this discrepancy between ratings and reality can cause problems is determining safe legal load limits for bridges, which are used to decide whether larger trucks may cross the bridge with an overload permit,” says Catherine French, CSE Distinguished Professor in the Department of Civil, Environmental, and Geo- Engineering and the study’s principal investigator.

“Our goal was to evaluate whether the current guidelines regarding shear forces (which transfer the loads to the supports) may be overly conservative for these older concrete bridges that are in good condition.”

Sponsored by MnDOT, the study was conducted by a team of U of M researchers including Carol Shield (co-investigator) and Benjamin Dymond.

Researchers used a multipronged approach consisting of numerical modeling and tests in both the laboratory and the field. The numerical modeling was used to apply the results of the laboratory and field tests to a study examining the effects of key parameters on the distribution of shear in a bridge system. Parameters included span length, girder spacing and depth, deck thickness, and load position.

Results showed that the shear forces for some bridges are not as high as those predicted by distribution factors in the current specifications—at least partially explaining why some MnDOT bridges with low shear ratings show no signs of distress, French says. The researchers provided recommendations for more refined methods of evaluating prestressed concrete girder bridges that rate low for shear and developed a screening tool to identify which bridges that rate low for shear should be further analyzed.

“The results of this project will help us re-evaluate aging bridges in our inventory, to distinguish those that really do have shear problems from those that don’t, and make decisions about whether they need to be replaced or rehabilitated for extra capacity,” says Yihong Gao, bridge designer with MnDOT’s Office of Bridges and Structures.

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Maintenance Operations, Research, Traffic and Safety

Reducing speeds to improve safety for work-zone flaggers

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When drivers approach a roadway work zone at high speeds, they put the lives of work-zone flaggers at risk. To keep flaggers safe on the job, U of M researchers are looking for better ways to capture drivers’ attention—and compel them to slow down—as they approach flagger-controlled work zones.

Kathleen Harder, director of the Center for Design in Health, and John Hourdos, director of the Minnesota Traffic Observatory, identified and tested new work-zone warning elements to more effectively capture and sustain driver attention. The project was funded by MnDOT and the Minnesota Local Road Research Board.

The project began with a simulator study in which participants completed three drives, each featuring a work zone with different warning treatments. One condition was a traditional four-sign configuration currently used to warn drivers approaching work zones. The other two conditions featured a variety of new elements, including signage with new messaging such as  a “one-lane road ahead” sign with flashing LED lights, a dynamic speed warning sign equipped with a loud warning horn that sounded if drivers exceeded the speed limit, and portable rumble strips.

“Overall, we found that the new set of elements is more effective than the elements currently used to reduce driving speeds on the approach to a flagger-controlled work zone,” Harder says.

Although adding LED lights to the one-lane road sign had no significant effect on drivers’ speeds, findings indicated that the dynamic speed sign coupled with the horn was more effective than the dynamic sign alone.

To test these new elements under real-world conditions, the researchers conducted field tests evaluating two configurations in Minnesota work zones. The first configuration followed the minimum standards outlined in the Minnesota Manual on Uniform Traffic Control Devices. The second deployed signs employing new messaging and attention-getting devices, including a dynamic speed warning sign, horn, and rumble strips.

Findings showed that the combination of the dynamic speed warning sign and the horn successfully reduced the overall speed of vehicles approaching the work zone. The portable rumble strips did not cause any significant speed reduction, but this may have been related to their location downstream from the dynamic speed sign and horn.

“Our findings reveal that the new set of elements designed to capture driver attention—including new messaging, a dynamic speed trailer, and horn—had a significant influence on reducing driver speed,” Harder says. “The experimental layout practically eliminated high-speed outliers and successfully reduced the approach speed to the flag operator.”

Research, Traffic and Safety

New work-zone warning app featured on KARE 11

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A new app that sends warning messages to drivers as they approach work zones was featured on KARE 11 News on Thursday. The app was developed by U of M researchers in a project sponsored by MnDOT.

The story aired as part of KARE 11’s #eyesUP campaign to end distracted driving.

The app works by pairing with Bluetooth low-energy tags placed in work zones, triggering audio warnings in smartphones that are within their range. This allows drivers to get a warning message without having to look down at their phones—or at warning devices such as changeable message signs outside their vehicles. And if a driver is being distracted by their phone, the app will interrupt whatever they are doing to provide a warning that a work zone is up ahead.

U of M researchers Chen-Fu Liao and Nichole Morris, who worked on the project, are interviewed in the story, along with Ken Johnson, work-zone, pavement marking, and traffic devices engineer at MnDOT.

Bicycling, Pedestrian, Research

New manual helps agencies count bike, pedestrian traffic

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As part of an ongoing effort to institutionalize bicycle and pedestrian counting in Minnesota, MnDOT has published a new manual designed to help city, county, state, and other transportation practitioners in their counting efforts.

The Bicycle and Pedestrian Data Collection Manual, developed by University of Minnesota researchers and SRF Consulting Group, provides guidance and methods for collecting bicycle and pedestrian traffic data in Minnesota. The manual is an introductory guide to nonmotorized traffic monitoring designed to help local jurisdictions, nonprofit organizations, and consultants design their own programs.Bicycle and Pedestrian Data Collection Manual

Topics covered in the manual include general traffic-monitoring principles, bicycle and pedestrian data collection sensors, how to perform counts using several types of technologies, data management and analysis, and next steps for nonmotorized traffic monitoring in Minnesota. Several case studies illustrate how bicycle and pedestrian traffic data can be used to support transportation planning and engineering.

The manual was completed as part of the third in a series of MnDOT-funded projects related to the Minnesota Bicycle and Pedestrian Counting Initiative, a collaborative effort launched by MnDOT in 2011 to encourage nonmotorized traffic monitoring across the state. U of M researchers, led by professor Greg Lindsey at the Humphrey School of Public Affairs, have been key partners in the initiative since its inception.

In addition to the manual, U of M researchers have published a final report outlining their work with MnDOT on this project. Key accomplishments include:

  • A new statewide bicycle and pedestrian traffic-monitoring network with 25 permanent monitoring locations
  • A district-based portable counting equipment loan program to support MnDOT districts and local jurisdictions interested in nonmotorized traffic monitoring
  • Minnesota’s first Bicycle and Pedestrian Annual Traffic Monitoring Report
  • A MnDOT website for reporting annual and short-duration counts that allows local planners and engineers to download data for analysis
  • Provisions added to MnDOT equipment vendor agreements that enable local governments to purchase bicycle and monitoring equipment
  • Annual training programs for bicycle and pedestrian monitoring
  • Provisions in the Statewide Bicycle System Plan and Minnesota Walks that call for bicycle and pedestrian traffic monitoring and creation of performance measures based on counts

“This is an excellent resource that steps through all aspects of managing a count program, and I think it will be very helpful to other states and organizations that want to implement their own programs,” says Lisa Austin, MnDOT bicycle and pedestrian planning coordinator. “Since Minnesota is a leader in counting bicycle and pedestrian traffic, it also fulfills what I think is an obligation to share our story with others.”