Tag Archives: minnesota department of transportation

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

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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 technology aimed at making rural intersections safer

This video above showcases a new kind of intersection conflict warning system being developed for use primarily by local agencies at rural, two-way stop intersections. Called the ALERT System, it uses a simple but ingenious combination of radar, wireless communication and flashing LEDs to alert drivers to the presence of approaching vehicles, thereby helping them identify safe gaps in the cross traffic and avoid potentially deadly collisions.

These types of systems are nothing new; MnDOT and other state DOTs have been developing them for more than a decade under the ENTERPRISE pooled fund program. MnDOT also recently kicked off a three-year project to deploy 20–50 of its Rural Intersection Conflict Warning Systems at selected at-risk intersections across the state. The main difference with the ALERT System is that it’s designed to be cheaper and easier to deploy than existing ICWS technologies. While that might sound like an incremental improvement, the difference for cash-strapped local agencies could be huge.

Since the ALERT System uses solar power, it doesn’t have to be hooked up to the power grid — which means that, in theory, county public works crews could install it themselves. The system also uses a simplified controller that doesn’t require a traffic signal technician to install and maintain, and detects vehicles using radar rather than in-pavement sensors. These factors might encourage greater adoption of ICWS technologies, which studies have shown to reduce both the frequency and severity of crashes.

The project is now in its second phase. It still faces a number of hurdles before could be ready to deploy, but Vic Lund, the traffic engineer for St. Louis County and the project’s main champion, says the results so far have been encouraging. In the video below, Lund shares his thoughts on the project, its challenges and the future of Intelligent Transportation Systems in Minnesota.

Learn more:

Bicycle and pedestrian research roundup

Judging by the response we get whenever we post anything bicycle- or pedestrian-related on MnDOT’s social media channels, people seem to be hungry for research into this area. We recently had several new reports arrive on the topic, and I thought I’d share them here for those who missed them, along with links to any related webinars or news articles.

The Minnesota Bicycle and Pedestrian Counting Initiative: Methodologies for Non-motorized Traffic Monitoring

This study examined ways of counting non-motorized traffic (bicycles and pedestrians), with the goal of helping planners and engineers better incorporate these modes into our transportation systems. The report discusses the pros and cons of various counting methodologies (i.e. manual field observation, active and passive infrared systems, magnetic loop detectors, etc.) and looks at how Minnesota agencies are using them. The project also included a webinar, workshops and a coordinated statewide pilot count in dozens of communities around the state.

Best Practices Synthesis and Guidance in At-Grade Trail-Crossing Treatments

At-grade trail crossings have frequently been the sites of bicycle, pedestrian and snowmobile crashes in Minnesota and throughout the nation. The goal of this document is to synthesize best practices observed statewide and nationally in order to provide engineers and other transportation professionals with guidance on safety treatment applications at trail crossings.

Minnesota’s Best Practices for Pedestrian/Bicycle Safety

This Local Road Research Board-funded guide is designed to be used as a resource to assist local agencies in their efforts to more safely accommodate pedestrians and bicyclists on their systems of roads and highways. It discusses the relative merits of a wide range of strategies to reduce crashes involving bicycles and pedestrians.

Complete Streets Implementation Resource Guide for Minnesota Local Agencies

In this project, investigators developed a guide to help local agencies implement Complete Streets programs, including sample policy language from agencies in Minnesota, systems for classifying roadways that are appropriate for use in context-sensitive planning and a worksheet to help develop specific project plans.

Bike, Bus, and Beyond: Extending Cyclopath to Enable Multi-Modal Routing

Researchers incorporated multimodal routing into the Cyclopath bicycle route-finding tool to allow users to find routes that combine biking and transit for journeys where biking alone is impractical. Increasing the percentage of trips made by methods other than cars is a MnDOT priority, and providing route information can help to make alternative transportation options more viable.

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

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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:

Free Complete Streets webcast next week

On Tuesday, June 4, the University of Minnesota is hosting a free Complete Streets seminar. The event will serve as a preview of a forthcoming guide, “Complete Streets Planning and Implementation at Multiple Scales Guidebook and Case Studies,” funded by MnDOT and the Minnesota Local Road Research Board.

Unfortunately, the event itself is sold out, but you can still watch it online for free via webcast. You can find all the relevant information on this web page, including direct links to the webcast sessions:

http://www.eventbrite.com/event/6109392357

According to the announcement, the event will cover “examples of Complete Streets policies, design guidance, engagement strategies, and financing mechanisms that help communities move from policies and plans to on-the-ground projects.”

Portable weigh-in-motion system demonstration

Weigh-in-motion (WIM) systems consist of sensors placed in road pavements to measure the weight of vehicles passing over them, along with other data such as speed, axle load and spacing, and vehicle type. This data is used to enforce weight limits on trucks and is also useful in a wide range of other applications, such as pavement design and traffic analysis.

However, constructing and maintaining permanent roadside WIM stations is expensive, so these systems are installed primarily on roadways with heavy traffic, such as interstate and trunk highways, and rarely used for rural local roads. Meanwhile, heavy truck volumes on local roads are increasing, significantly shortening their lives. A less costly, portable WIM system is needed for such roads so that collected data can be used to better design these roads to accommodate heavy truck traffic.

One solution for bringing WIM technology to local roads is to implement a portable, reusable system similar to pneumatic tube counters used to conduct traffic counts. With funding and technical assistance from MnDOT and the Local Road Research Board, Professor Taek Kwon of the University of Minnesota—Duluth has developed a prototype system that has already proven to be nearly as accurate as the more expensive, permanent systems.  MnDOT Research Services staff drove up to MnROAD this week to observe a live demonstration of the technology, and made this short video.

The research being conducted here is part of an implementation project based on Kwon’s original study, the results of which can be found in this research report and its accompanying two-page technical summary from MnDOT Research Services.

White House honors MnDOT traffic boss for work on rural intersection safety

The White House named Minnesota Department of Transportation State Traffic Engineer Sue Groth one of its 12 transportation “Champions of Change” for her role in implementing life-saving technology to help prevent collisions at rural intersections. The rural intersection conflict warning systems, which use sensors and lights to give motorists real-time warnings about traffic conditions, were developed by MnDOT’s Office of Traffic, Safety and Technology.

It’s worth noting that MnDOT Research Services and the University of Minnesota are also currently working on a project to develop a low-cost version of these systems using LEDs and solar panels. The ongoing research, being conducted by University of Minnesota— Duluth Professor Taek Kwon, is a continuation of the Advanced Light-Emitting Diode Warning System project completed in 2010.

Here’s the press release from MnDOT:

ST. PAUL, Minn. – On Wednesday, May 8, 2013, the White House honored Sue Groth, Minnesota Department of Transportation’s state traffic engineer, as one of 12 people who are Transportation “Champions of Change.” The Champions event, “Transportation Technology Solutions for the 21st Century,” focused on individuals or organizations that have provided exemplary leadership in developing or implementing transportation technology solutions to enhance performance, reduce congestion, improve safety and facilitate communication across the transportation industry at the local, state or national level.

“These Champions represent the very best in American leadership, innovation and progress,” said Secretary Ray LaHood. “I’m proud to recognize these transportation leaders who work every day to grow our economy and help us reach our destinations more quickly, efficiently and safely.”

The MnDOT Office of Traffic, Safety and Technology has been selected as a Champion of Change for their work to reduce fatal and life-changing crashes on Minnesota roadways, while enhancing mobility for all users. OTST is being honored for designing, testing and helping to deploy dozens of life-saving rural intersection conflict warning systems throughout Minnesota, while leading a national effort to do more of the same throughout rural America. These systems save lives at rural intersections that might otherwise not warrant or afford more traditional traffic control devices or geometric improvements.

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Research partnerships create better pavements

As is painfully evident this time of year, Minnesota’s weather is highly destructive to our asphalt roadways.  One of the biggest challenges for transportation practitioners in cold-climate states like ours is low-temperature cracking in asphalt pavements. The distress caused by  our extreme weather variations and constant freeze-thaw cycles wreaks havoc on our asphalt streets and highways, causing decreased ride quality, increased maintenance costs and shorter pavement lifespans.

On April 17, the Center for Transportation Studies presented its 2013 Research Partnership Award to the team members of a multi-state, Minnesota-led study designed to combat the problem. The project, Investigation of Low Temperature Cracking in Asphalt Pavements, Phase II,” was a national pooled-fund study involving six state DOTs, four universities, the Minnesota Local Road Research Board and the Federal Highway Administration. It resulted in a new set of tools — test methods, material specifications and predictive models — that will be used to build longer-lasting pavements.

The project is a prime example of the value and benefits of cooperative research. Each organization brought its own unique strengths and expertise to bear on the problem. The University of Minnesota, led by Professor Mihai Marasteanu, brought its strength in lab testing of binders and mixtures, for example; other universities leveraged their respective expertise in data analysis, statistics and modeling capabilities. MnDOT, as the lead state agency, controlled the finances and kept the research on track, guiding the process through technical advisory panels. MnDOT’s materials laboratory and its unique MnROAD pavement research facility also played a key role in the study.

The above video provides an excellent overview of the project and includes commentary from key MnDOT and University of Minnesota team members. MnDOT is already moving to implement the results. It plans to use the new test procedure on several road construction projects this year. Iowa and Connecticut are among the other states reportedly planning implementation projects.

See also:

2013 Research Partnership Award winners

From left: University of Minnesota Professor Mihai Marasteanu, the project’s principal investigator; MnDOT State Aid Director Julie Skallman; MnROAD Operations Engineer Ben Worel; and CTS Associate Director for Development and Finance Dawn Spanhake, who presented the award. (Photo by Cadie Adhikary, Center for Transportation Studies)