All posts by Christine Anderson

New recommendations aim to help roadside turfgrass thrive

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.

Gauging safety of heavy vehicles on older concrete bridges

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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Reducing speeds to improve safety for work-zone flaggers

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.”

New work-zone warning app featured on KARE 11

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.

New manual helps agencies count bike, pedestrian traffic

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.”

Work-zone warnings could soon be delivered to your smartphone

Imagine that you’re driving to work as usual when your smartphone announces, “Caution, you are approaching an active work zone.” You slow down and soon spot orange barrels and highway workers on the road shoulder. Thanks to a new app being developed by University of Minnesota researchers, this scenario is on its way to becoming reality.

“Drivers often rely on signs along the roadway to be cautious and slow down as they approach a work zone. However, most work-zone crashes are caused by drivers not paying attention,” says Chen-Fu Liao, senior systems engineer at the U’s Minnesota Traffic Observatory. “That’s why we are working to design and test an in-vehicle work-zone alert system that announces additional messages through the driver’s smartphone or the vehicle’s infotainment system.”

As part of the project, sponsored by MnDOT, Liao and his team investigated the use of inexpensive Bluetooth low-energy (BLE) tags to provide in-vehicle warning messages. The BLE tags were programmed to trigger spoken messages in smartphones within range of the tags, which were placed on construction barrels or lampposts ahead of a work zone.

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The researchers also developed two applications for the project. First, they designed a smartphone app to trigger the audio-visual messages in vehicle-mounted smartphones entering the range of the BLE work-zone tags. A second app allows work-zone contractors to update messages associated with the BLE tags remotely, in real time, to provide information on current conditions such as workers on site, changes in traffic, or hazards in the environment.

Field tests proved the system works. “We found that while traveling at 70 miles per hour, our app is able to successfully detect a long-range BLE tag placed more than 400 feet away on a traffic barrel on the roadway shoulder,” Liao says. “We also confirmed the system works under a variety of conditions, including heavy traffic and inclement weather.”

“This was a proof of concept that showed that smartphones can receive Bluetooth signals at highway speeds and deliver messages to drivers,” says Ken Johnson, work-zone, pavement marking, and traffic devices engineer at MnDOT. “Future research will look into how we should implement and maintain a driver alert system.”

This future work includes using the results of a human factors study currently under way at the U’s HumanFIRST Laboratory to create recommendations for the in-vehicle message phrasing and structure. Then, researchers plan to conduct a pilot implementation with multiple participants to further evaluate the system’s effectiveness.

According to MnDOT, another phase of the project may investigate how to effectively maintain the BLE tag database. This phase could also investigate implementation options, such as how MnDOT can encourage drivers to download and use the app.

Taconite byproduct reduces road wear from studded tires

In a recent project, the Alaska Department of Transportation (DOT) used a byproduct of Minnesota’s taconite mining industry for a section of the Alaska Glenn Highway.

The taconite byproduct—Mesabi sand—serves as the aggregate of a sand-seal treatment for a 4,600-foot stretch of the highway just north of Anchorage. Sand seals are an application of a sealer, usually an emulsion, immediately followed by a light covering of a fine aggregate (the sand).

“Our goal was to explore pavement preservation measures that extend pavement life and that also resist studded tire wear,” says Newton Bingham, central region materials engineer with the Alaska DOT. “Studded tires are allowed from mid-September until mid-April, and they cause rapid pavement wear.”

For the project, the Alaska DOT obtained sample pavement cores from the test area in 2014. Researchers then applied sand seals with two different hard aggregates—calcined bauxite and the Mesabi sand—to the surface of the cores to evaluate the effectiveness of each treatment.

Larry Zanko, senior research program manager of the Natural Resources Research Institute (NRRI) at the University of Minnesota Duluth, was the on-site representative for the taconite sand analysis. NRRI focuses on strategies to recover and utilize mineral-resource-based byproducts such as taconite and find potential beneficial end-uses for them.

“Taconite is one of the hardest natural aggregates,” he says. “Minnesota’s taconite mining industry generates tens of millions of tons of byproduct materials every year that could be used as pavement aggregate. Friction aggregates could be a higher-value niche for the industry.”

Testing of the sand-seals showed similar wear resistance for both types of aggregates. “We chose taconite sand since it is available from Minnesota as an industrial byproduct, whereas calcined bauxite sand has to be imported from nations on the Pacific Rim and costs more due to shipping,” Bingham says.

The Alaska DOT reports good performance to date on Glenn Highway and is funding ongoing pavement wear measurement.

NRRI researchers are also studying the use of taconite for other pavement applications. Funded by MnDOT, Zanko’s team developed (and later patented) a taconite compound for repairing pavement cracks and patching potholes (see an article the September 2016 Catalyst). The long-lasting patches reduce maintenance costs and traffic disruption. In continuing work funded by the Minnesota Local Road Research Board, researchers will refine the repair compound and develop and field-test a low-cost mechanized system for pavement and pothole repairs.

Bicycling industry, events have economic impact in Minnesota

The bicycling industry in Minnesota—including manufacturing, wholesaling, retail sales, and non-profits and advocacy groups—produced an estimated total of $780 million of economic activity in 2014. This includes 5,519 jobs and $209 million in annual labor income (wages, salaries, and benefits) paid to Minnesota workers.

These findings are an important component of a multifaceted report from U of M researchers. Their research, funded by MnDOT, provides a comprehensive understanding of the economic impact and health effects of bicycling in Minnesota.

“This kind of bicycling study is definitely new for Minnesota but also new nationally,” says Sara Dunlap, principal planner in MnDOT’s Office of Transit. “This is the first time a state has attempted to assess, in a single study, the multiple impacts that bicycling activities have on the state’s economy and health.”

Xinyi Qian, an Assistant Extension Professor in the U’s Tourism Center, was the project’s principal investigator. For the bicycling industry portion of the work, the co-investigators were Neil Linscheid, Extension Educator, and Brigid Tuck, senior economic impact analyst, both with U of M Extension.

“Information about the bicycling industry is scattered, so we filled the information gaps by creating a list of bicycle-related businesses in Minnesota, interviewing bicycle-related business leaders, surveying bicycle-related businesses, and gathering additional information from relevant sources,” Linscheid says. “Numerous industries and a diverse supply chain are involved.”  The research team then used this information to enhance an economic model that shows the economic contribution of the bicycling industry in Minnesota.

“Minnesota has a strong bicycle-related manufacturing industry that drives the bicycle-related economy,” Tuck says. “Specialty bicycle retail stores, especially independent ones, are a critical component of the bicycle retail industry in Minnesota.” Additionally, she says, when asked about local suppliers, bicycling businesses often provided names of other Minnesota companies, many of which are also bicycle-related businesses.

Researchers also looked at the economic impact of bicycling events—races, non-race rides, fundraising events, mountain bicycling events, high school races, and bicycle tours. Qian led this portion of the study, working with Tuck.

Through surveys and analysis, they found that an average bicycle event visitor in 2015 spent a total of $121 per day. This spending translates into an estimated total of $14 million of annual economic activity, which includes $5 million in annual labor income and 150 jobs. Event participants also brought additional people with them— more than 19,000 visitors who were travel companions but did not ride in any event.

The findings can help bring together event organizers and officials of various organizations—economic development, transportation, public health, and tourism—to promote the event facilities, the host communities, and bicycle tourism as a whole.

“Bicycling event attendees and their travel companions are a valuable audience for shopping, recreation, and amusement activities,” Qian says. “Communities hosting events could explore opportunities to capture additional spending from these important visitors.”

Qian notes that the analysis focused on event visitors and was not a broad measure of bicycle tourism.

A previous post discussed the health impacts component of the study; in April, we’ll report on the magnitude of biking in the state.

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Videos trace progress in traffic operations, pavement design

Last month, CTS debuted two videos about the many contributions U of M researchers have made—and are still making—in traffic operations and pavement design.

The videos are one of the ways CTS is marking 30 years of transportation innovation. Our goal is to show how research progresses over time—from curiosity to discovery to innovation. The videos also show how U of M research meets the practical needs of Minnesotans in the Twin Cities metro and throughout the state.

The first video focuses on improving traffic operations, a research focus since our earliest days. Professor Emeritus Panos Michalopoulos invented Autoscope® technology to help transportation agencies capture video images of traffic and analyze the information, enabling better traffic management. Autoscope was commercialized in 1991, and the technology has been incorporated into products sold and used worldwide.

Current traffic operations research builds on this strong foundation. For example, the U’s Minnesota Traffic Observatory, directed by John Hourdos, develops data collection tools such as the Beholder camera system. The system is deployed on high-rise rooftops overlooking a stretch of I-94 in Minneapolis—an area with the highest crash frequency in Minnesota—to help the Minnesota Department of Transportation reduce congestion and improve safety.

The second video showcases U of M research on pavement design. Developing pavements that can stand up to Minnesota’s harsh climate is a continuing priority for researchers, whose work has led to new methods, tools, and specifications to extend pavement life. The video also looks at how research teams are pushing the envelope with use of materials such as taconite waste and graphene nano-platelets for pavement applications.

 

Mobility, labor, and competitiveness drive discussion at annual freight symposium

How does the ability to move freight affect the economic health of a state, region, and even a city? How are the supply chains of businesses impacted by freight flow? And what challenges and opportunities does Minnesota face when it comes to leveraging and strengthening its freight modes?

The 2016 Freight and Logistics Symposium offered a thoughtful examination of those questions and explored other topics related to improved mobility in Minnesota, including congestion, regulation, labor shortages, and the value of all freight modes to the state’s economy.

The event, held December 2, 2016, in Minneapolis, included:

  • A presentation on the power of freight flow data in attracting industry to a location and ways to use data in making a compelling case for businesses to invest
  • A panel Q&A featuring four industry experts from diverse organizations that depend on reliable freight movement
  • A discussion of how the 2016 election results may affect freight transportation

For a full summary of the event, download the 2016 Freight and Logistics Symposium proceedings (PDF).


The symposium was sponsored by CTS in cooperation with MnDOT, the Minnesota Freight Advisory Committee, the Council of Supply Chain Management Professionals, the Metropolitan Council, and the Transportation Club of Minneapolis and St. Paul.