Tag Archives: university of minnesota

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.

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.

Patching pavement with microwaves and magnetite

On Wednesday, I had a chance to watch a demonstration of a uniquely Minnesotan pavement patching technology that combines an industrial-strength microwave with a special asphalt mix. What makes it “uniquely Minnesotan?” In addition to having been developed by University of Minnesota researchers and a Monticello-based company (and with some funding from MnDOT), this innovative method involves a special asphalt mix using magnetite, a mineral that abounds on Minnesota’s Iron Range.

It also addresses a very Minnesotan transportation problem: winter pavement repair. In the video above, Kirk Kjellberg of Microwave Utilities, Inc., highlights some of the benefits of using the 50,000-watt microwave to heat the pavement during patching. In addition to creating a longer-lasting patch, the microwave is considerably faster than many alternative techniques. The technology is still relatively new, but its supporters claim it allows for pavement repairs in the middle of winter that are as strong and durable as the ones road crews do in the summer.

The demonstration, which was organized for members of the Local Road Research Board, took place at MnDOT’s District 3 training facility in St. Cloud.

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Minnesota hosts annual meetings of transportation librarians

Last month, the Center for Transportation Studies and the MnDOT Library hosted the joint annual meetings of the Transportation Library Connectivity & Development Pooled Fund Study TPF-5(237), the Midwest Transportation Knowledge Network (MTKN), and the Western Transportation Knowledge Network (WTKN). Librarians from fourteen state DOTs, several universities, the Portland Cement Association, and the National Transportation Library met on the University of Minnesota campus and at MnDOT’s Central Office building, with some members attending portions of the meetings remotely.

Photo of a group of librarians in the MnDOT Library
MnDOT Librarian Qin Tang leading a tour of the library. Photo by Nick Busse

The packed agendas included:

  • Business and committee meetings
  • A presentation on bridge inspection by David Hedeen, P.E., from MnDOT’s Bridge Office
  • A copyright workshop led by Nancy Sims of the University of Minnesota Libraries
  • Tours of the MnDOT Library and the Minitex Document Delivery area and MLAC (Minnesota Library Access Center) Cavern at the University of Minnesota

“Each individual library cannot collect everything. Filling these gaps from our partner libraries is one of the benefits of transportation libraries networking. Our customers and ultimately our agencies benefit from this relationship-building.” – Sheila Hatchell, MnDOT Library Director

About Transportation Knowledge Networks

Transportation knowledge networks (TKNs) are organized groups of transportation libraries and others that collaborate to share their information resources and improve information access. There are currently three regional TKNs in the United States. The ultimate goal of sharing resources and working together cooperatively is to help transportation practitioners find information they need, when they need it—saving time and money, and getting better results for their organizations. The MTKN’s DOT State Stats is one example of a collaborative tool developed by TKN members.

Emerging topics

A few topics emerged as common themes for members:

  1. How to value library services: Sheila Hatchell from the MnDOT Library shared her recent experiences with developing a valuation methodology. The Library Connectivity Pooled Fund study is considering a proposal for multiple libraries to conduct valuation studies. Last year, the Library Connectivity and Development Pooled Fund Study developed Proving Your Library’s Value: A Toolkit for Transportation Librarians (PDF), led by members A.J. Million (formerly of Missouri DOT), Sheila Hatchell, and Roberto Sarmiento (head of the Northwestern University Transportation Library). This is a terrific resource for all libraries to use in developing their own valuation studies.
  2. Data curation: The ubiquity of data, large size of data sets, and stronger requirements for data management plans for federal research grants mean that skills in data management and curation are more important than ever. Librarians can help researchers understand and comply with open data requirements as well as help our organizations manage data. Leighton Christiansen of Iowa DOT will take the lead to assist TKN members in this area.
  3. TKN planning: The National Transportation Library and the AASHTO RAC TKN Task Force are working with the regional TKNs and the Library Connectivity and Development Pooled Fund Study to develop a national transportation knowledge network. (See the business plan for TKNs: NCHRP Report 643: Implementing Transportation Knowledge Networks)

‘Intelligent’ traffic drum could help prevent work-zone tragedies

2012-26 Image
A prototype of the Intelligent Drum Line system.

Work-zone safety is a serious, ongoing challenge for transportation agencies. According to MnDOT, the current three-year average for Minnesota work zones is 1,819 crashes and seven fatalities per year. And that’s not counting near-misses: just talk to anyone who has worked as a flagger, and they will likely have a story about diving into a ditch to avoid being hit by a distracted driver. Consequently, MnDOT is constantly exploring ways to make work zones safer — which brings me to the photo above.

What you’re looking at is no ordinary traffic cone. It’s a prototype of a new warning device called the Intelligent Drum Line system — basically a modified orange traffic drum packed with electronics that can detect speeding drivers and blast them with audiovisual cues to let them know they’re entering the work zone too fast.

Our new technical summary explains the details of the new system, which was developed at the University of Minnesota, with funding and in-kind assistance from MnDOT:

The prototype design uses two modified traffic drums placed 1 to 3 feet from the shoulder of the road and 300 to 400 feet apart. Sensors in the first drum detect vehicles, measure their speed and distance, and communicate this information to the second drum…

When the IDL system detects an oncoming vehicle traveling faster than a threshold speed, the system activates visual warning systems in both drums and initiates a countdown. When the speeding vehicle is approximately 1 second away from the first drum, the system activates an air horn to warn the driver.

As the vehicle passes the first drum, the audible alarm terminates and the system transmits a command to the second drum to start another countdown. When the vehicle is approximately 1 second away from the second drum, the system activates another audible alarm.

Testing of the IDL system at MnROAD has been successful; however, researchers still need to study how drivers react to the system in real-world conditions. Before they can do that, the design will have to be refined so that it can pass Federal Highway Administration crashworthiness tests. On a related note, MnDOT is currently funding a separate University of Minnesota study into which technologies are most effective at capturing drivers’ attention in work zones. The study will include visual and auditory cues similar to the ones used in the IDL prototype.

Learn more:

Introducing new CTS blog: Conversations

CTS Conversations blog iconCTS is pleased to announce a new blog—CTS Conversations—that will highlight the full spectrum of transportation research, education, and outreach at the University. Supplementing the Catalyst newsletter and the Crossroads blog, the Conversations blog will share timely updates on research publications, events, and training from CTS and its programs.

Also, the blog will feature topical questions to spark conversation and interaction with our readers. Check out the current question and join the conversation!

U of M Research: Spurring private-sector development along transit corridors

developmentA new research study is recommending ways to make it easier for developers and employers to select sites that encourage living-wage jobs and mixed-income housing near transit.

A key finding of the study, which was based on interviews with developers and business leaders, revealed a pent-up demand for transit access in the Twin Cities metropolitan region.

A team led by University of Minnesota researchers Yingling Fan and Andrew Guthrie found that providing a great work location is critical for employers in recruiting highly skilled young professionals who are likely to desire—or demand—urban living and access to transit.

They also found that multifamily residential developers, redevelopment specialists, and large corporate office tenants have a strong interest in transit-accessible sites, but regulatory barriers, cost issues, and uncertainty surrounding future development of transit often discourage both developers and businesses from selecting such sites.

More details about the study and key recommendations

What happens when you incentivize transit use during construction projects

In 2010, MnDOT began a three-year long, $67 million repair and upgrade project on I-35 in Duluth. Dubbed the “Mega Project,” it created a serious disruption for Duluth-area commuters. To help mitigate the impact, the Duluth Transit Authority stepped up its bus services, offering free rides in newly established bus-only express lanes as well as access to new park-and-ride lots and various other enticements. Perhaps not surprisingly, many area residents took advantage of their new transit options to avoid construction-related travel delays. But what’s really interesting is what happened after the construction ended.

As described in a recently published MnDOT/University of Minnesota study, commuters who started taking the bus to avoid traffic caused by the construction ended up continuing to ride the bus even after the construction ended. Researchers surveyed riders during and after the 2010 and 2011 construction seasons and found that, even after bus fares went back to normal levels, only 15 percent of the new bus users switched back to driving. Researchers concluded that once riders developed a habit of using transit, the habit tended to stick.

The report author sums up the phenomenon quite nicely in her executive summary:

Human beings are creatures of habit. Most of us travel the same route every day to the same destination. Sometimes, however, something comes along to push us to examine our habits and possibly change them. A major highway construction project can be such an event. (…) This provides a very good opportunity to examine our travel patterns and possibly change our habitual modes.

Of course, this change didn’t just happen on its own. As the technical summary notes, the DTA marketed its services aggressively during this period. (The above photo is just one example.) The study also noted that the elimination of expanded bus services in the winter had a negative impact on ridership.

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Advanced hybrid buses have better fuel economy, fewer emissions

One of Metro Transit’s new advanced “super hybrid” buses—built in Minnesota and billed as the cleanest, most efficient diesel-electric hybrid buses in the United States—garnered national attention at the American Public Transportation Association’s Bus and Paratransit Conference May 5–8 in Indianapolis.

Photo of superbus
Photo: Metro Transit

Unique because of its all-electric accessory systems, the bus was featured at the event so that transit professionals from across the country could experience this new hybrid technology firsthand, says Chuck Wurzinger, assistant director of bus maintenance at Metro Transit. The bus is one of two advanced hybrids built for Metro Transit in 2012. They currently operate on local routes with frequent stops in downtown Minneapolis and its surrounding communities.

The decision to purchase the new hybrids was greatly influenced by the results of a University of Minnesota study aimed at improving fuel economy in diesel-electric hybrid buses, Wurzinger says. The “Superbus” study, led by mechanical engineering (ME) professor David Kittelson, included an energy audit of major accessory systems on a standard hybrid bus. The study was funded by Metro Transit, CTS, and the U of M’s Institute for Renewable Energy and the Environment (IREE).

Study findings indicated that up to half of the fuel consumed by hybrid buses is used to power accessory systems. According to the research team, powering these systems electrically could significantly improve fuel efficiency.

The new advanced hybrids do just that, using all-electric systems to power the heating, air conditioning, engine fans, power steering, and air compressor. These components improve fuel economy, reduce emissions, and allow the buses to be operated in electric-only mode for short periods.

Photo of Metro Transit diesel-electric bus
Photo: Metro Transit

One of the buses also has start/stop capabilities, which allow the engine to shut down at bus stops and traffic lights. “This reduces engine idle time while maintaining all other bus functions, including passenger comfort and safety features,” Wurzinger says.

Although the buses have been in service for only a short time, they are already showing promising increases in fuel economy, Wurzinger says. “We have also operated them consistently on electric power inside the bus garage, which helps keep the air clean in the building. This reduces the amount of ventilation required in cold weather, which means less energy is used to heat the building.”
Metro Transit has more than 130 hybrid buses in services--about 15% of its total fleet

Along with a standard hybrid bus and a conventional diesel transit bus, one of the advanced hybrids will be monitored and evaluated in a new study conducted by U of M researchers in collaboration with Metro Transit. The multidisciplinary research team includes Kittelson, ME associate professor Will Northrop, ME research associate Winthrop Watts, and applied economics associate professor Steven Taff.

As part of the study, funded by IREE, the team will collect real-world, on-the-road data from the three buses in all seasons on a variety of route types. The researchers then plan to compare the efficiency and emissions of the buses and make recommendations to Metro Transit about which configuration is the best for a given application. Data collected from the study will also allow Metro Transit to work with bus manufacturers to optimize bus performance.

“We believe the results will be useful in writing bus technical specifications and also in determining if a certain type of bus is best suited to a certain type of bus route,” Wurzinger says.

Ultimately, this information could be used to determine which buses to assign to which routes as well as which type of bus to purchase given fleet replacement or expansion requirements.

The project is scheduled for completion in 2015.

Reprinted from the CTS Catalyst, June 2013.

‘Three Ways to Cook a Pothole’

In April, we posted about an innovative pothole-filling technology being developed by the Minnesota Department of Transportation and the University of Minnesota, Duluth. The technique involves zapping pothole patches and the surrounding pavement with a special truck-mounted, 50,000-watt microwave. Researchers have found that heating the base and the patch material at the same time creates a stronger, longer-lasting bond that provides for a more permanent pothole fix.

Last week, the MnDOT/UMD microwave technology found its way into a new MnDOT video (above) that also explores two other experimental pothole-patching methods. One involves using a large “electric oven”-type heating element instead of a microwave. The other utilizes a new exothermic (i.e. heat-generating) asphalt mixture containing taconite from northern Minnesota mines. The video compares the potential benefits of all three of the new technologies, which the department hopes will someday lead to “more pothole-patching power for the taxpayer dollar.”

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