All posts by Shannon Fiecke

Marketing and Communications Manager, MnDOT Research Services

Innovative pavement textures reduce noise, improve fuel economy

What if something as simple as changing the texture of the pavements we drive on could not only increase safety, but also reduce noise pollution and boost our vehicles’ fuel economy?

It’s possible, according to the latest research from MnROAD, the state’s one-of-a-kind pavement research facility. In a new report, investigators detail how quieter pavement textures, such as those applied by grinding grooves into pavements with diamond-coated saw blades (see the photo above), may also reduce rolling resistance — the force that resists a tire as it moves across the pavement’s surface.

The potential benefits to the public are significant. A 10-percent reduction in rolling resistance could reduce the U.S. public’s fuel consumption by 2–3 percent, eliminate up to $12.5 billion in fuel costs each year (as well as cutting carbon emissions). Add on the cost savings from reducing noise pollution (building noise barriers along highways can cost as much as $3 million per mile), and it’s clearly a win-win situation.

In the study, researchers used an innovative line-laser profiler to develop three-dimensional representations of test pavement surface textures. They then investigated the relationship between these surface characteristics and data on rolling resistance that was collected during a 2011 study using a special test trailer developed by researchers in Poland. This year, the same trailer will be used to conduct a second round of rolling resistance measurements at MnROAD.

The research is related to an ongoing pooled-fund study on concrete pavement surface characteristics. The goal is to produce data that will allow MnDOT to identify ideal ranges for surface characteristics that improve pavements’ quietness and ride quality while keeping them safe and durable.

Learn more
Researchers relied on rolling resistance data from a study conducted in 2011 with a test trailer developed by the Technical University of Gdańsk, Poland. This was the first time such measurements were taken in the United States.
Researchers relied on rolling resistance data from a study conducted in 2011 with a test trailer developed by the Technical University of Gdańsk, Poland. This was the first time such measurements were taken in the United States.

MnROAD earns concrete pavement association award

Staff from MnROAD, the Minnesota Department of Transportation’s cold weather road research facility in Albertville, Minn., were presented with the Marlin J. Knutson Award for Technical Achievement by the American Concrete Pavement Association in December.

The award cites the facility’s well-deserved reputation for being a place where both agency and industry ideas are put to the test. This award was presented as a tribute to the agency’s commitment to learning and putting ideas into practice.

The Marlin J. Knutson Award for Technical Achievement is presented to an individual or group who has made significant contributions to advance the development and implementation of technical innovations and best practices in the design and construction of concrete pavements.

(far right) Gerald Voigt, ACPA president and CEO, presented MnDOT with the Marlin J. Knutson Award for Technical Achievement during a ceremony in December. Receiving the award are (from left) Luke Johanneck, Bernard Izevbekhai, Roger Olson, Tom Burnham, Glenn Engstrom, Maureen Jensen and Sue Mulvihill. (Photo courtesy of the ACPA)
(Far right) Gerald Voigt, ACPA president and CEO, presented MnDOT with the Marlin J. Knutson Award for Technical Achievement. Receiving the award are (from left) Luke Johanneck, Bernard Izevbekhai, Roger Olson, Tom Burnham, Glenn Engstrom, Maureen Jensen and Sue Mulvihill. (Photo courtesy of the ACPA)

“MnROAD is helping to make roads last longer, perform better, cost less, construct faster, and have minimal impact on the environment,” said Gerald Voigt, ACPA president and CEO. “It is a model for other agencies to follow.”

MnROAD is a pavement test track initially constructed between 1991-1993. It uses various research materials and pavements and finds ways to make roads last longer, perform better, cost less to build and maintain, be built faster and have minimal impact on the environment. MnROAD consists of two unique road segments located next to Interstate 94.

Staff from the MnROAD facility in Albertville were recognized during the ACPA’s Distinguished Service and Recognition Awards ceremony in December. (Photo by David Gonzalez)
Staff from the MnROAD facility in Albertville were recognized during the ACPA’s Distinguished Service and Recognition Awards ceremony in December. (Photo by David Gonzalez)

This article, authored by Rich Kemp, originally appeared in Newsline, MnDOT’s employee newsletter. 

LRRB research showcased at pavement and dust control conferences

The Transportation Engineering and Road Research Alliance and Road Dust Institute conferences are being jointly held this week in Minneapolis. Among the many research topics being presented are several recently completed studies funded by the Minnesota Local Road Research Board.

The LRRB, which celebrates its 55th anniversary this year, is one of only two statewide organizations in the United States that fund transportation-related research projects and education on behalf of local governments.  In honor of the TERRA and dust control events, we thought we’d take the opportunity to highlight a few of the latest pavement and dust control-related research projects from the LRRB.  If you’re at TERRA today, be sure to stop by their booth and check out their latest research results, videos and more.

Recycled Asphalt Pavement: Study of High-RAP Asphalt Mixture on Minnesota County Roads 

This report summarizes the field performance of local roads containing recycled asphalt pavement (RAP), associated field and laboratory work with asphalt activation, and design and performance testing of high-RAP bituminous mixtures. Conclusions include:
• Transverse cracking performance of county highways averaging 20 to 26 percent RAP was improved when PG 52-34 binder was used.
• Coarse aggregates from plant mixing achieved a more uniform coating and were subjected to less abrasion than those from laboratory mixing.
• IDT critical temperature results showed that the addition of RAP significantly increased the critical temperature, predicting less crack resistance.

Research using Waste Shingles for Stabilization or Dust Control for Gravel Roads and Shoulder

Minnesota generates more than 200,000 tons of shingle waste each year. While a small portion of recycled asphalt shingle waste (RAS) can be incorporated into hot-mix asphalt (HMA) pavement mixtures, there is still a lot of waste left over, prompting MnDOT to investigate other potential uses. Alternative options include improving the performance and quality of gravel surfacing and reducing dust by replacing common additives such as calcium chlorides with RAS. This will remove valuable RAS materials from the waste stream, supplement the use of more expensive materials, and improve the performance of local roads.

Aggregate Roads Dust Control: A Brief Synthesis of Current Practices

More than half of our local roadways are gravel roads, making them a vital part of our transportation system. To help control the dust on gravel roads, the Minnesota LRRB has developed a new guidebook, which summarizes a variety dust suppressants, their effectiveness, and impacts.

More than half of our local roadways are gravel roads, making them a vital part of our transportation system. One of the drawbacks and biggest complaints about gravel roads is the dust they produce when vehicles drive over them.  Residents that live on gravel roads deal with the dust that settles on their homes, yards, and parked cars. Dust can also have adverse effects on air quality and the environment. To help control the dust on gravel roads, the Minnesota LRRB has developed this new guidebook, which summarizes a variety dust suppressants, their effectiveness and impacts.

Culvert research aims to protect endangered small fish

The Topeka shiner
The Topeka shiner, a small minnow that inhabits slow-moving prairie streams, was once widespread and abundant in portions of Iowa, Kansas, Minnesota, Missouri, Nebraska and South Dakota. It now inhabits less than 10 percent of its original geographic range.
(Photo courtesy of the Minnesota Department of Natural Resources)

In a new study funded by the Minnesota Department of Transportation, engineers are trying to ensure that new culverts do not degrade the habitat of an endangered fish in southern Minnesota.

The state has already researched how to better accommodate fish passage at river and stream crossings. Now it is looking at design guidelines for culverts that specifically impact the Topeka shiner, a small endangered fish found in five Midwestern states.

In Minnesota, the Topeka shiner is known to live in at least 57 streams, totaling 605 miles, within the Big Sioux and Rock River watersheds.

“The Topeka shiner is reported to have been erased from about 50 percent of its historic range in Iowa and much of its range in Minnesota, which is why Minnesota is so intent on doing what it can to help this fish thrive here,” said Alan Rindels, MnDOT’s project coordinator for the research.

The Topeka shiner is endangered due to the degradation of stream habitat, stream channelization, non-native predatory fishes and construction within waterways.

Culverts might impede the passage of this small minnow for a number of reasons, including that they might be too long, lack sufficient depth or carry water too fast.

Culverts allow water to pass under roads.
Culverts (also called small bridges) allow water to pass under roads. Occasionally, they can harm a stream’s fish habitat by inadvertently acting as a barrier to fish passage or migration. On the West Coast, large-scale efforts are under way to protect migratory salmon, and in Minnesota, culvert designers are concerned about fresh water species.

In addition, long culverts block sunlight, which possibly discourages fish from swimming through. Typically, older culverts are replaced with longer culverts to improve road safety and minimize maintenance costs. To eliminate or minimize impacts to the Topeka shiner, the state is trying to determine if light mitigation strategies are necessary.

Researchers from the University of Minnesota’s St. Anthony Falls Research Laboratory will monitor a newly installed culvert (110 feet in length) and a few other culverts in critical Topeka shiner habitat streams during spawning and fall movement.

Additionally, a laboratory-based light manipulation experiment will examine the behavior of the warm-water fish when presented with a dark culvert.

Guidelines for culvert design in Topeka shiner habitat will be developed based on these results, as well as examples from neighboring states. The state is also collaborating with the U.S. Fish and Wildlife Service and affected Minnesota counties.

Reducing confusion at two-lane roundabouts

Minnesotans have grown accustomed to roundabouts as they’ve proliferated throughout the state, but many motorists are still confused by the less common two-lane roundabout.

While roundabouts have been shown to reduce vehicle delay and severe crashes, the few Minnesota cities with this type of multi-lane roundabout have had a prevalence of driver mistakes.

In Woodbury, two such roundabouts were converted into smaller, one-circulating-lane designs due to driver confusion.

The City of Richfield had no such option at the high-volume Portland Avenue and 66th Street, a formerly signalized intersection that carries about 30,000 vehicles per day. (See video)

Crash-prone and congested prior to its reconstruction in 2008, a two-lane roundabout seemed to be the practical solution for this intersection. But although the roundabout reduced overall crashes, the intersection still had more fender benders than designers were comfortable with, according to City Engineer Kristin Asher.

“The crashes were primarily related to improper left-turns from the outside lane and failure to yield at the entry,” she said.

Not only were drivers unsure which lanes they should use to enter or exit the roundabout, they didn’t know how to respond to other cars inside the roundabout. (See news story)

“People don’t understand they have to yield to both lanes inside the roundabout,” explained University of Minnesota researcher John Hourdos.

In a recently completed study funded by the Minnesota Local Road Research Board, researchers from the Minnesota Traffic Observatory examined whether sign and pavement marking changes would improve performance.

The city of Richfield extended the solid lines leading up to the intersection from 50 to 250 feet to encourage drivers to choose the correct lane before entering the roundabout. It also replaced fish-hook-style roundabout signs with traditional lane designation signs and did away with complex striping patterns.

These before and after photos show the original fish-hook style pavement markings, left, which were replaced with a more traditional design. (Photos courtesy of the city of Richfield)
Before and after photos show the original fish-hook style pavement markings, left, that were replaced with a more traditional design.
(Courtesy City of Richfield)

Hourdos examined two years of traffic data to see how motorists responded to the improvements that were made in 2011.

He found 50 percent more drivers entered the correct lane from the get-go, which led to a reduction in improper turns within the roundabout. Lane violations were also reduced by 20 percent.

“One of the main problems was drivers didn’t know they have to choose one of the two lanes,” Hourdos explained. “Then once they were inside the roundabout, they were forced to either deviate from their course or commit a violation.”

The city also increased sign visibility to address yielding problems; however, these changes didn’t seem to make a difference.

With state and federal guidelines lacking much guidance for how to sign two-lane roundabouts, the LRRB is funding a new study for three other multi-lane roundabouts: in St. Cloud, at Highway 169/494 and one planned for the future realignment of County Roads 101 and 61 between Chanhassen and Shakopee.

Report: Effect of Signing and Lane Markings on the Safety of a Two-Lane Roundabout (PDF, 4 MB, 72 pages)

Update (1/30/2014): Watch the LRRB’s new video on how to navigate a multi-lane roundabout.

New guidelines developed for counting bike, pedestrian traffic

Image
Manual field counts require more labor than automatic technologies, but they can collect deeper data about demographics and helmet use. Both forms of monitoring are necessary to give a complete picture of bicycle and pedestrian traffic in the state.

To prepare for a multimodal future, state agencies must be able to plan and engineer a transportation system for all modes of transportation, including bicycle and pedestrian traffic.

The Minnesota Bicycle and Pedestrian Counting Initiative was launched to develop consistent methods for monitoring non-motorized traffic across the state. Researchers developed guidelines for manual counts using state and national examples, and they also created methods for extrapolating annual traffic volumes from short-duration automated counts, for integration into MnDOT’s vehicular count database program.

The guidance developed for manual counts includes forms, training materials, public information for passers-by, links to smartphone applications that provide counting locations and spreadsheets for reporting results.

MnDOT hosted six workshops and a webinar to introduce local officials to the initiative and recruit participants for pilot field counts. Researchers then analyzed how these field counts could be used with existing automated counts to extrapolate daily or annual data.

MnDOT has installed some of the very first automated counting equipment on a state road — Central Avenue NE in Minneapolis (on the bike lane) and Highway 13 in Eagan (on a shoulder). As of 2012, six agencies in Minnesota counted non-motorized traffic (annual reports are available from the city of Minneapolis and Transit for Livable Communities), and even though comprehensive data is not yet available, Minnesota is a leader in this type of monitoring with more than 1,000 manual count locations and 32 automatic count sites.

Because of Minnesota’s experience, researchers collaborated with the National Cooperative Highway Research Program’s national Methodologies and Technologies for Collecting Pedestrian and Bicycle Volume Data research project, due for release in 2014, and contributed to the Federal Highway Administration’s effort to update its Traffic Monitoring Guide to include a chapter on non-motorized traffic.

Learn more:

New study to shed light on environmental impacts of deicers

Even naturally derived products like corn syrup and beet juice can impact the environment when applied to salt mixtures for winter roadways.

A wide range of products, including the ones mentioned above, are added to deicing mixes to limit the amount of salt needed for Minnesota roads each winter. However, although information is available about the corrosive properties of various deicing chemicals, less is known about the toxicity of these compounds, especially to the aquatic environment.

Thanks to a recently completed project sponsored by the Clear Roads Pooled Fund, MnDOT winter maintenance personnel will better understand the relative toxicity of eight common deicing agents, which also include non-organics like Magnesium Chloride, Calcium Chloride and Potassium Acetate.

“Because the state has been trying a lot of different alternative chemicals, we wanted to get a better handle on the environmental impacts,” said MnDOT engineer Tom Peters, the technical liaison for the 26-member, Minnesota-led pooled fund for winter maintenance research.

In January, researchers plan to release a concise summary of the toxicity rankings to help winter highway maintenance managers consider both expected levels of service and potential harm to the environment when selecting a deicer.

A Dec. 3 webinar available on the Clear Roads website discusses their findings.

About Clear Roads

Minnesota is the lead state for the Clear Roads Pooled Fund, which conducts rigorous testing of winter maintenance materials, equipment and techniques. Other recent and upcoming research (see our Technical Summary on the program) includes a winter maintenance cost-benefit analysis toolkit, snow removal techniques at extreme temperatures and environmental factors that can cause fatigue in snowplow operators.

You can learn more about Clear Roads via the project’s e-newsletter.

Robotic message painter could help keep road crews safe

Using rollers and stencils to draw turn arrows and crosswalk stripes on roads seems a bit archaic to MnDOT District 3 Maintenance Superintendent Randy Reznicek, who asked researchers if they could develop an automated road message painter.

University of Minnesota-Duluth Associate Professor Ryan Rosandich has taken that vision and created an robotic arm that can spray-paint pavement signs, with the goal of saving crews time and keeping them safer.

Designed to be mounted to the front of a maintenance vehicle, the robot is operated remotely by a laptop, programmed with numerous types of messages.

In an earlier prototype, researchers developed a trailer painter that could be pulled behind a truck.

Crews currently use heavy, eight-foot by four-foot stencils and rollers to paint designs, with an estimated 75 percent of such work involving the repainting of existing markings.

“It takes two people to lift the stencils,” explained MnDOT maintenance worker Joe Gilk, whom Reznicek presented with the idea about five years ago. “This would eliminate one position. One person could just run the truck and you could use that other person in another area of our job.”

Rosandich, who heads the Mechanical and Industrial Engineering Department at the University of Minnesota-Duluth, led the initial development of a software system and trailer painter.

MnDOT has funded further research to develop the more technically difficult robotic arm, which it anticipates could be used in other aspects of maintenance work as well.

MnDOT District 3 maintenance worker Joe Gilk, left, and maintenance superintendent Randy Reznicek watch the demonstration of the robotic message painter, an idea that came from their office.
MnDOT District 3 maintenance worker Joe Gilk, left, and District 1 traffic engineer Rob Ege watch a demonstration of the robotic message painter, an idea that came from Gilk’s office.

Rosandich recently demonstrated the mechanical arm to a MnDOT road crew (no paint was used during the demonstration), but additional software and mechanical tweaks remain before researchers take the machine out for final testing on the pavement this spring.

A companion vision system is being developed to identify existing markings to guide the robot in the repainting of existing messages.

The robot’s three-segmented aluminum shell arm is capable of painting up to a 12-foot wide lane and has enough battery power for a whole day’s worth of work, Rosandich said.

Once the prototype is complete, researchers hope to find a manufacturer to develop and produce a machine that could be used by maintenance crews across the state. MnDOT has already had great success in deploying automated pavement patching systems in some districts.

Not only would a robotic message painter free up maintenance crews and speed up sign-painting, but Rosandich sees worker safety as its “biggest selling point.”

The start-up cost for manufacturing such a device is estimated to be $150,000.