Maintenance Operations, Research

Taking the guesswork out of measuring winter operations

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Being able to accurately and reliably estimate traffic conditions during snow events is critical to transportation agencies. Typically, state DOTs use measurements such as “time to bare pavement”—based on the visual inspection of plow drivers—to gauge the progress of snow operations. These estimates are limited, however, by the subjectivity and inconsistency of human-based measurements.

Now, new research sponsored by the MnDOT and led by University of Minnesota Duluth civil engineering professor Eil Kwon aims to take the guesswork out of assessing traffic conditions during winter weather events.

“Dr. Kwon’s research on a new approach to snow and ice performance reporting is exciting,” says Steve Lund, state maintenance engineer and director of the Office of Maintenance at MnDOT. “For quite a few years, MnDOT snowfighters have been reporting their performance through a visual review of the roadway conditions. Our snowfighters have a tough job—automating the performance reporting will remove that task from their duties. Also, looking at traffic returning to a ‘normal’ condition is truly the ultimate goal or outcome measure, and where we want to go.”

In the first phase of this project, researchers developed a prototype process that uses data on traffic speed, flow, and density collected by loop detectors in the Twin Cities metro area to estimate the point at which traffic patterns return to normal—an indicator that the roadway surface has “recovered.” In the newly published second phase, researchers further analyzed the traffic flow patterns during snow events under normal and snow conditions and refined the earlier prototype into a traffic-data-based measurement process for snow operations.

“We found that by comparing the variation patterns in traffic flow during a snow event with those during normal weather conditions, we could successfully identify the recovery status of the traffic flow at a given location,” Kwon says.

Based on their findings, the researchers developed a new process to identify the Normal Condition Regain Time (NCRT)—as an alternative to the traditional “time to bare pavement” measurement used to gauge the progress of maintenance operations during a winter weather event.

One advantage of the new process is that it can reflect how road surface conditions affect traffic flow differently during day and night periods. “Nighttime traffic flow patterns are substantially different from those during daytime periods,” Kwon says. “We identified normal traffic patterns separately for daytime and nighttime conditions to account for these differences in estimating the recovery status.”

Future research plans include the development of an operational version of the NCRT estimation system that can be used on a daily basis to analyze and improve snow operations, and the creation of an online version that can be used for coordinating snow operations in real time.

“There is a lot of potential to use these findings to make snow operations even more effective and efficient,” Kwon says. “For example, the analysis of the relationship between the NCRT measures and operational strategies such as plowing start time and methods could help further refine MnDOT’s winter maintenance strategies.”

For more information, download the technical summary (PDF) or the project’s final report.

Maintenance Operations, Traffic and Safety

Video Demonstration: Robotic Message Painter Prototype

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In the above video, University of Minnesota-Duluth Associate Professor Ryan Rosandich tests a prototype of a robotic arm he developed to paint messages and markings on roadways. He calls the machine “The MnDOT Robot.”

During a test run in October 2015, the MnDOT robot painted a right-turn arrow and the word “ahead” on pavement at MnDOT’s Pike Lake station in Duluth.

Rosandich hopes commercial companies will show an interest in further developing his proof-of-concept technology into something that road authorities can use regularly to make work easier, faster and safer for their employees.

Companies interested in commercializing this technology can contact Andrew Morrow at amorrow@umn.edu.

Editor’s Note: The paint used in the above demonstration was diluted due to the cold weather at the time of the demonstration and does not reflect the condition of the paint expected in a typical application.

Traffic and Safety

Internship program helps students build skills, make connections

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While some interns spend their days making copies and coffee runs, Caitlin Johnson spent her summer internship working on a research project exploring ways to improve safety in work zones.

Johnson, a fifth-year civil engineering student, is one of eight undergrads from the University of Minnesota who participated in this year’s Summer Transportation Internship Program.

Interns worked at MnDOT for 10 weeks and gained valuable transportation-related experience in areas ranging from designing roadways to measuring pavement movement. The program, offered jointly by CTS and MnDOT, is now in its fourth year.

This year’s participants included the following students, working in these MnDOT offices:

  • Caitlin Johnson, Office of Traffic, Safety and Technology
  • Mamadou Mbengue, Office of Environmental Stewardship
  • Ellie Lee, Office of Design
  • Luke Horsager, Bridge & Hydraulics Office
  • Sheue Torng Lee, Materials & Pavement Office
  • Trenton Pray, Materials & Concrete Office
  • Colleen Tamara Maluda, Environmental & Vegetation Office
  • Lucas Karri, Bridge Office

Johnson says her internship at MnDOT gave her the opportunity to study a topic that hasn’t been explored in-depth in the past and present those findings to industry professionals, including staff from the Federal Highway Administration. Luke Horsager, a civil engineering senior, spent his internship with the Bridge & Hydraulics Office equipping MnDOT boats with new GPS and Bluetooth software used for river mapping and monitoring bridge scour. He says he enjoyed gaining hands-on experience with the technology.

Heidi Gray, a MnDOT Metro District designer who supervised intern Ellie Lee in the Office of Design, says the internship program is valuable not only for the students, but also for the supervisors and MnDOT as a whole. While the interns gained important hands-on work experience and made valuable professional connections, MnDOT supervisors were introduced to talented young professionals.

“It’s really good to get young people in here and teach them what MnDOT is all about,” Gray says. “I personally have enjoyed the opportunity to teach and pass along what I know. It’s a good refresher.”

Application materials for the 2016 Summer Transportation Internship Program will be available on the CTS website in early November.

For more information, read the full article in the September issue of Catalyst or visit the internship program web page.

Aviation, Bridges and Structures

Using drones to inspect bridges

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MnDOT is researching how data and images collected by drones, such as the Aeryon Skyranger shown here, could aid bridge inspectors.
MnDOT is researching how data and images collected by drones, such as the Aeryon Skyranger shown here, could aid bridge inspectors.

In recent years, drones made headlines for fighting wars overseas, detecting crop conditions, keeping an eye on power lines and even delivering retail goods.

As the flying electronic devices became easier to use and less expensive, all sorts of individuals, businesses, nonprofit groups and government organizations – including the Minnesota Department of Transportation (MnDOT) – are exploring ways to use them.

This past summer, MnDOT began researching how to employ these unmanned aerial vehicles, or UAVs, to someday help inspect the state’s many bridges.

“That day may still be far off, but our initial project was an encouraging first step,” said Jennifer Zink, MnDOT bridge inspection engineer. “Phase 2 of the project will better provide details as to methods, criteria and cost effectiveness for how to apply drone technology best to bridge inspection.”

Project goal

Using drones could also minimize risks associated with current bridge inspection methods, which include rope systems and special inspection vehicles. (Photo by D.R. Gonzalez, MnDOT)
Using drones could help minimize risks associated with current bridge inspection methods, which include rope systems and special inspection vehicles. (Photo by D.R. Gonzalez, MnDOT)

The research team tested drones this past summer while inspecting four Minnesota bridges (in Chisago County, Olmsted County, Morrison County and near Stillwater) specifically selected for the study after an extensive evaluation and FAA approval.

Zink and her colleagues wanted to investigate whether drones could help MnDOT decrease the rising costs of bridge inspections and collect more detailed information. Drones could also minimize the risks for bridge inspectors, who currently use rope systems and special inspection vehicles to access hard-to-reach areas. Using a drone to gather images could keep inspectors out of harm’s way and inspection vehicles out of active traffic lanes.

“The goal of the project was to study the effectiveness and possibilities of using UAVs to aid in bridge inspection work, typically in gathering images without the use of an under-bridge inspection vehicle and in areas where access is difficult or not safe for an inspector,” Zink said. “There is no substantive guidance in existence for this application of this evolving technology. This initial effort was to gain a better understanding of potential capabilities, processes and planning best practices.”

FAA approval

Before simply launching drones and collecting bridge data, the research team reviewed current FAA rules and applied for the necessary exemptions. Approval was granted, but only for the use of an Aeryon Skyranger drone. Even though exemptions for several models were submitted to the FAA, none were approved in time for the field study.

The team, which included personnel from Collins Engineers Inc. and Unmanned Experts, also worked closely with the MnDOT Office of Aeronautics to plan the project and gain the necessary approvals. The Aeronautics Office recently published an official MnDOT drone policy.

In the air

Once in the air, the drone suitably performed a variety of inspection functions that didn’t require a hands-on physical inspection. Researchers tested the drone’s ability to gather high-quality still images and video footage of bridges. They also collected data from infrared cameras. In addition, the drone provided the ability to capture data needed to construct maps of bridge areas and 3D models of bridge elements.

“The images, including infrared images to detect deck trouble spots, obtained from the drone correlate to the findings in the bridge inspection reports for specific bridge elements,” Zink said.

Missing from the research were images of the underside of bridges. The drone model used in the study wasn’t able to shoot images upward from beneath a bridge, and inspectors identified that as a key feature along with the ability to operate without a GPS signal.

“The drone we used in this project was not completely ideal for an entire gathering of imagery for all bridge inspection elements as it was limited to GPS signal capability,” Zink said. “However, it did give us an idea of what a drone could provide, what the limitations were, and what features we would like to see on newly available UAV models. Unfortunately, our hands were tied with obtaining FAA exemptions only for the particular model used in this project within the funding timeframe.”

Conclusions and recommendations

The project’s final report listed several conclusions, including that drones can be used safely during bridge inspections and that risk to both the inspectors and public is minimal.

“Due to the successful outcome of the initial project, we have a better understanding of the drone capabilities we would like to use during an actual scheduled bridge inspection,” Zink said. “The drone that will be used in Phase 2 is specifically designed for inspection of structures. Several goals exist for the Phase 2 research project, and if we can accomplish them, they will decrease MnDOT’s costs and increase bridge inspection abilities. It could improve inspection data collection for local agencies as well.”

The researchers recently were notified that they received funding for Phase 2 of their project, which is expected to start later this fall.

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Traffic and Safety

Roadway deaths and what Minnesota is doing about it

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Joint article produced with MnDOT Research Services

Minnesota developed the Strategic Highway Safety Plan a decade ago, as the nation set a goal of reducing roadway deaths to less than one person per 100 million vehicle miles traveled. Last year, the nation still hadn’t reached this milestone (1.1 deaths occurred per 100 million miles), but Minnesota had lowered its fatality rate to 0.63 deaths (down from 1.48 deaths from 20 years ago).

“When I look at what Minnesota has done over the last 15 years compared to other states, we’re one of the few states that has a pretty consistent downward trend [in fatal crashes],” said Brad Estochen, MnDOT state traffic engineer, who gave an update on the highway safety plan during a recent presentation at the Roadway Safety Institute. “I think we’re doing some unique things here that have given us these results.”

These steps, Estochen says, have included passing a primary offense seatbelt law (seatbelt usage is now above 90 percent), investing in strategic safety infrastructure like high-tension cable median barriers and focused enforcement of DWI, speed and seatbelt laws.

Developing a plan

To best understand the risk factors for fatal and serious injury crashes, the state combined real-life crash data with input from professionals in engineering, law enforcement, emergency medical services, as well as everyday road users. The results showed that most crashes in the state involve multiple factors—such as road conditions, driver impairment and driver age.

Estochen said this approach of analyzing data and gaining stakeholder perspectives provided new insights into the dynamic causes of fatal and serious injury crashes.

In conjunction with the Departments of Health and Public Safety, MnDOT created a highway safety plan aimed at both professional stakeholders and the community that identified critical strategies for reducing serious traffic incidents. It has been updated in 2007 and 2014, most recently.

MnDOT also created a complimentary document for every county and MnDOT district (respectively called the county safety plan and district safety plan) to help local agencies identify locations and potential projects for reducing fatalities.

“We were the first state to take the SHSP concept to the local level. It was identified as a noteworthy practice by FHWA and other states are now starting to engage locals in developing specific plans for their use and implementation,” Estochen said.

The highway safety plan is an integral part of Toward Zero Deaths, the state’s cornerstone traffic safety program that has a goal of reducing fatalities to less than 300 per year by 2020.

Overall, Estochen said one of the best ways to reduce crashes in the state is to promote a culture of traffic safety — something he hopes the highway safety plan contributes to.

“Creating a traffic safety culture has nothing to do with building bigger and better roads,” he said. “It really has to do with making us as a state, as a community and as individuals responsible for our actions.”

Policy and Planning, Research

MnPASS extension on I-35E shaped by U of M study

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Based in part on a planning study conducted by U of M researchers at the Humphrey School of Public Affairs, MnDOT is extending MnPASS Express Lanes on Interstate 35E in the northeast Twin Cities. The extension will build on the project currently adding MnPASS lanes from Cayuga Street to Little Canada Road.

The study, funded by MnDOT and the Federal Highway Administration (FHWA), examined the feasibility of extending these MnPASS lanes from Little Canada Road north to County Road 96. During peak periods, MnPASS lanes provide a congestion-free option to transit vehicles, carpools, and motorcycles at no cost—and to single-occupant vehicles for a fee.

Led by Director Lee Munnich and Associate Director Frank Douma of the Humphrey School’s State and Local Policy Program, the U of M research team worked with Parsons Brinckerhoff to develop and evaluate several concepts for the MnPASS extension. The goal was to provide an option that reduced congestion for all users, including drivers in the general-purpose traffic lanes and transit users. The team also included Mary Vogel from the U’s Center for Changing Landscapes.

The primary challenge was how to handle MnPASS traffic through the recently reconstructed I-694/I-35E interchange. After going over several design options, the team recommended what it termed a “hybrid” option, which creates a continuous southbound MnPASS lane and a discontinuous northbound MnPASS lane through the interchange.

Researchers also engaged community stakeholders and corridor users to gather feedback about the proposed alternatives and worked to illustrate options that could facilitate greater transit, carpool, and vanpool use in communities along this section of I-35E.

Additional recommendations developed by the team—in partnership with representatives from MnDOT, the FHWA, and the Metropolitan Council—included continuing to educate community motorists about the MnPASS program as well as expanding transit options by creating more park-and-ride sites, encouraging mixed land uses, and building better walking and biking connections.

Based on these recommendations, MnDOT is moving forward with the hybrid option for the project, says Brad Larsen, director of the MnPASS Policy and Planning Program. MnPASS lanes will be added to southbound I-35E between County Road 96 and Little Canada Road; through the I-35E/I-694 commons area, the existing inside lane will be designated as a MnPASS lane during peak periods. There will be no MnPASS lane northbound through the commons area, but a lane will be added north of the interchange from County Road E to County Road J.

Construction on the extension project is expected to begin in March 2016, with the lanes slated to open in late 2016.

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(Featured photo courtesy of David Gonzalez, MnDOT.)

Bicycling, Pedestrian, Policy and Planning

Bike, pedestrian counting efforts engage local agencies statewide

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Across Minnesota, local agencies need better information about where and how many people are biking and walking to make decisions about infrastructure investments, understand safety risks, and even plan active living initiatives.

To help provide agencies with bicycle and pedestrian traffic data, U of M researchers have been working with MnDOT on the Minnesota Bicycle and Pedestrian Counting Initiative since 2010. The initiative is a collaborative, statewide effort to support bike and pedestrian traffic monitoring by local, regional, and state organizations.

Recently, the project team completed an implementation study—the second of three MnDOT-funded projects related to the initiative—specifically designed to engage local agencies. The goal was to demonstrate the feasibility of using both permanent and portable sensors to collect bicycle and pedestrian traffic data in several Minnesota cities, suburbs, and small towns.

“If we want to institutionalize counting and monitoring across the state, local agencies need to know it’s not something that’s only important for large cities like Minneapolis,” says principal investigator Greg Lindsey, professor at the Humphrey School of Public Affairs and current MnDOT scholar-in-residence. “We have to be on the ground in these places, illustrating that it’s relevant to the decisions they’re making.”

To that end, the team installed commercially available sensors—including inductive loops, passive infrared, pneumatic tubes, and radio beams—to collect traffic counts in several Minnesota cities. Overall findings indicate that all of the sensors produced reasonably accurate measurements—and that participating agencies found value in the collected data.

Findings and case studies from the study have already been incorporated into the draft Bicycle and Pedestrian Data Collection Manual, a new MnDOT guidance document being used in statewide training workshops. Also as a result of the study, MnDOT plans to include commitments to bike and pedestrian traffic monitoring in its forthcoming statewide bicycle and pedestrian plans. In addition, MnDOT is investing in a network of permanent traffic monitoring sites around the state as well as in portable equipment that will be available to local agencies.

Read the full article in the September issue of Catalyst.

Bridges and Structures, Environment

Designing fish-friendly culverts

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Roadways for humans can sometimes create roadblocks for fish, but researchers hope to establish a set of culvert design practices to help aquatic creatures get where they’re going.

Many fish depend on mobility along a river for feeding and spawning. Where roads meet rivers, however, culverts can block fish and other aquatic organisms that can’t navigate changes in current, lighting and other factors.

Waterway barriers threaten an already endangered species of minnow known as the Topeka shiner (pictured above). It can also be a big problem for economically important fish such as trout or northern pike. That’s why the Minnesota Department of Natural Resources prefers building bridges to culverts.

However, bridges are not always economically feasible, and so MnDOT is working closely with the DNR to develop culverts that protect both public safety and the environment.

Photo of boxed culvert
Culverts 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. There are nearly 11,000 culverts in Minnesota.
Sediment Content 

Recent research suggests that installing boxed culverts differently could greatly improve fish passage.

Culverts are typically placed a little below the streambed with the expectation that the stream flow will naturally fill them with sediment. Researchers tested that assumption and found it to not always be accurate.

“We found that pre-filling the culvert with sediment that replicates the streambed as part of the installation process helped prevent upstream erosion and the development of vertical drops that can become barriers to aquatic movement,” said Jessica Kozarek, a University of Minnesota research associate. “In addition, pre-filling the culvert helped ensure the sediment remained inside the culvert flows were high and water moved quickly during rainstorms.”

MnDOT has been working with the DNR to identify the conditions that determine whether a newly installed culvert will naturally fill with sediment, replicating surrounding streambed conditions, or whether a stream’s water flow will transport sediment out of a culvert.

Using an experimental flume at the University of Minnesota’s St. Anthony Falls Laboratory, researchers tested MnDOT’s standard box culvert design under a variety of stream conditions.

Laboratory simulations suggest that filling a culvert with sediment at installation, rather than allowing it to fill over time is, with some exceptions, generally the best ap­proach for low- and moderate-grade streams. Additionally, steep, fast-moving waters require a filled culvert with structures such as larger rocks to keep sediment in place. These structures also create steps, pools and riffles that enable fish to rest as they move upstream.

MnDOT will use this latest research, along with conclusions from other recent studies, to create a guide for fish-friendly culvert designs.

“Of all the things we’ve studied, there are maybe three or four research projects. This manual will pull it all together,” said Petra DeWall, state waterway engineer at the Minnesota Department of Transportation.

Further research is underway to determine whether aquatic organisms are deterred by low light conditions in long, dark culverts. Researchers are also looking into whether mussel spat rope could be used to create a rough bottom to reduce water speed in culverts with no sediment.

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Policy and Planning, Research

Census report looks at U.S. commuting patterns; U of M report analyzes Twin Cities’ patterns

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A recent report issued by the U.S. Census Bureau looks at commuting patterns by U.S. workers in 2013 using data from the American Community Survey. It highlights differences in rates of automobile commuting by key population characteristics such as age, race, ethnicity, and the types of communities in which workers live.

One finding of note: young people in big cities were much less likely to drive to work in 2013 than they were several years earlier. For instance, urban workers aged 25 to 29 showed about a 4-percentage-point decline in automobile commuting between 2006 and 2013.

You can also find an extensive analysis of commuting behavior that was produced locally. In a recent multifaceted study sponsored by the Metropolitan Council and MnDOT, U of M researchers analyzed travel behavior over time in the Twin Cities.

The extensive five-part study report is based on the rich set of data produced by the Met Council’s Travel Behavior Inventory household travel survey. David Levinson, RP Braun/CTS Chair in the U’s Department of Civil, Environmental, and Geo- Engineering, was the study’s principal investigator.

The five components of the report examine:

  • Changes in travel duration, time use, and accessibility
  • Changes in walking and biking
  • The effect of transit quality of service on people’s activity choices and time allocation
  • Changes in travel behavior by age cohort
  • Telecommuting and its relationship with travel and residential choices

For more information:

Traffic and Safety

Engaging the next generation of the transportation workforce

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In July, CTS introduced the next generation of the workforce to transportation topics and careers during a two-week summer program. Thirty students entering seventh through ninth grade attended the CTS-hosted National Summer Transportation Institute, where they got hands-on experience with topics ranging from distracted driving to aeronautics to traffic management.

As part of the program, attendees toured campus, visited the U of M’s transportation-related labs, and learned tips on researching, studying, public speaking, and writing. In addition, participants learned about many aspects of transportation, including human factors, roadway safety, bridge design, surveying, and traffic simulation.

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The camp also included outings to several MnDOT facilities, UPS, Metro Transit, the Minneapolis–St. Paul International Airport, the Minnesota Transportation Museum, and boat tours of the St. Croix River Crossing construction site and St. Paul Port Authority.

Highlights for attendees included riding the light rail and going behind the scenes in a Metro Transit control room, watching airplanes take off and exploring maintenance equipment at the airport, getting up close to bridge construction on the St. Croix River Crossing boat tour, and using a driving simulator to learn about distracted driving at UPS.

“I really enjoyed using the driving simulators,” said one of the ninth-grade program participants. “It was a hands-on experience that truly taught me the dangers of texting while driving and how much harder it really is.”

In post-program evaluations, parents reported that their children had learned valuable information about transportation topics, careers, and related education opportunities.

“This was one of the best camps we have ever experienced,” one parent said. “There was always a plan for college, and this program increased enthusiasm, preparedness, and maturity.”

“[The program] opened up my daughter’s horizon for future career choices and major focus areas after high school,” another parent said.

The program was sponsored by CTS with funding from the Federal Highway Administration administered by the Minnesota Department of Transportation (MnDOT).

To learn more, read the full article in the August issue of Catalyst.

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