Category Archives: Traffic and Safety

research, Traffic and Safety

New Project: Does lowering speed limits reduce driver speeds on urban streets?

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In 2019, the Minnesota Legislature passed a law reducing barriers for cities to systematically lower speed limits. The City of St. Louis Park followed this guidance by reducing speed limits in 2021, but initial speed data collected before and 6–8 months after the changes showed little to no short‑term impact. Because driver behavior is habitual and may change slowly, advocates suggest that greater reductions in operating speeds may emerge over time, highlighting the need for repeat monitoring between 2025 and 2027.

To receive email updates about this project, visit MnDOT’s Office of Research & Innovation to subscribe.

This study aims to evaluate whether longer‑term changes have occurred 2–4 years after the initial reductions, while also examining other Minnesota agencies that have implemented or are considering reduced speed limits. The research will gather both measured and anecdotal data, assess “after” speed conditions where needed, and analyze how effectiveness varies based on roadway characteristics and any accompanying speed reduction countermeasures. These efforts address lingering questions about how speed limit changes influence driver behavior and roadway safety over time.

Understanding speed is critical because it directly affects the safety of all road users. According to Minnesota Motor Vehicle Crash Facts 2022, speeding was the leading cause of traffic fatalities, contributing to 130 of the state’s 444 deaths. By identifying agencies that have reduced speed limits, evaluating short‑ and long‑term impacts, and analyzing site‑specific factors, this research will produce guidance to help Minnesota road agencies assess and implement effective speed limit reductions.

“There is renewed interest in lower speed limits on municipal-type streets,” said Victor Lund, traffic engineer with St. Louis County’s Public Works Department. “The objective of this research is to better understand the intersection of speed limit policy, driver behavior and safety, which will result in guidance to better inform policies, practices and speed limits that support safer streets.”

The Objectives:

  1. Identify local agencies in Minnesota that have implemented reduced speed limits or may consider implementation along with any speed reduction countermeasures that have been implemented with the reduced speed limits.
  2. Evaluate the short-term and long-term effects of speed limit reductions implemented in Minnesota through the collection and analysis of speed data.
  3. Assess how these effects vary based on site characteristics or speed reduction countermeasures that were implemented in coordination with the reduced speed limit.
  4. Based on the findings, develop a summary document to aid Minnesota road agencies in assessing potential speed limit reductions.

Project Details:

  • Estimated Start Date: 06/25/2025
  • Estimated Completion Date: 06/30/2027
  • Funding: MnDOT and Local Road Research Board
  • Principal Investigator: Peter Savolainen
  • Co-Principal Investigators: Tim Gates
  • Technical Liaison: Victor Lund

Details of the research study work plan and timeline are subject to change.

To receive email updates about this project, visit MnDOT’s Office of Research & Innovation to subscribe.

Traffic and Safety

Evaluating the Use of a Common Alternative Deicer

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When temperatures fall below 15 degrees Fahrenheit (F), salt loses its effectiveness at melting snow on roads. To accommodate lower temperatures, transportation agencies often combine an alternative deicer with salt brine to treat roads and return them to an appropriate level of service. This project investigated the most common alternative deicer used in Minnesota to provide guidance to state and county winter maintenance managers about its application at different concentrations and temperatures.

Continue reading Evaluating the Use of a Common Alternative Deicer →
research, Traffic and Safety

New Project: Can Enhancing Color on Dynamic Message Signs Improve Clarity and Safety?

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The majority of MnDOT’s dynamic message signs (DMS) are equipped to produce full color/full matrix messaging. Current signage regulations refer to retroreflective colors for static signs, but MnDOT aims to extend and modify existing standards and guidelines by exploring differences between static signs and DMS.

To receive email updates about this project, visit MnDOT’s Office of Research & Innovation to subscribe.

This research will systematically explore and optimize the use of different colors and color-coding schemes in DMSs to resemble the retro-reflectivity of static signs and examine how legibility, visibility, and effectiveness can be improved. Optimizing DMS colors to mimic retroreflective static sign colors and adapting them to myriad environmental conditions, MnDOT can realize reduced driver distractions, improved information comprehension, and increased safety. The project will also support improved decision-making processes by providing evidence-based guidance for future standards and practices for MnDOT beyond.

A pilot study will be conducted to assess the recommended color settings against benchmark real-world conditions. Empirical data on the new configurations will measure their performance, confirm their effectiveness and identify any adjustments required prior to broader implementation.

“Not all color is created equal! As illustrated in the three graphics below, federal standards for reflective sheeting and striping, NEMA standards for colors, and the triangle of visible light LED lights can produce do not correspond,” said Terry Haukom, senior engineer with MnDOT’s Regional Transportation Management Center. “This variance has caused the signage industry to display colors that meet federal standards but do not look correct to the human eye. In addition to exploring this incongruity, our research is focused on understanding and comparing what typical travelers understand and expect when viewing traffic information on the web, and whether the travel time numbers displayed on our signs can give drivers a better understanding of the travel time to the listed destination if it was displayed with a color scheme that leveraged web-based maps.”

The Objectives:

  1. Standardize the emitted colors from MnDOT’s DMS according to NEMA TS4 and MUTCD specifications, ensuring they match the retroreflected colors of static signs and align with current LED capabilities
  2. Document the public’s perception of optimum color if different from standards based on human factors feedback
  3. Document the public’s perception of dark pixel around graphics on emitted colors on DMS
  4. Research and document the public’s perception of emitted colors on DMS compared to static sign messages, and explore the incorporation of web-based travel time map colors to enhance visibility and clarity, especially with colors like amber

Project Details:

Details of the research study work plan and timeline are subject to change.

To receive email updates about this project, visit MnDOT’s Office of Research & Innovation to subscribe.

Pedestrian, research, Traffic and Safety

CTS Webinar: How Infrastructure Shapes Driver Behavior and Pedestrian Safety

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Tuesday, May 19, 2026, 12:00–1:30 pm Virtual

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About the Event 

Improving pedestrian safety requires a deeper understanding of how people interact with roadway design and infrastructure. This webinar will highlight two recent research efforts examining how transportation infrastructure influences driver behavior and pedestrian safety outcomes.

Curtis Craig, a research associate in the Human Factors Safety Laboratory, will present findings from two complementary studies examining infrastructure at intersections. The first study explored how right turn lane configurations affect pedestrian safety using a combination of behavioral analysis and multiple research methods. The second project examined how drivers and pedestrians respond to different infrastructure treatments and how those designs influence behavior in real-world environments.

These study findings offer transportation agencies, planners, and engineers practical considerations as they work to create safer and more accessible pedestrian environments.

Registration and More

This webinar is free, but registration is required. Visit the event web page to register and for more information. 

Related Reading

Active Research by Curtis Craig

Analysis and Risk Management of Motorcycle, Bicycle, and Pedestrian Crashes in Minnesota

Traffic and Safety

Alerting Drivers Dangerously Approaching Work Zones

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Motorists driving dangerously in work zones present a safety risk to workers and themselves. Alerting these drivers about their driving behavior before they reach the work zone could reduce the number of work zone crashes and enhance work zone safety. This project developed and evaluated the performance of a device that provides audio and visual alerts to drivers whose vehicles are approaching work zones at a high speed and on a dangerous trajectory.

Continue reading Alerting Drivers Dangerously Approaching Work Zones →
Traffic and Safety

Evaluating the Safety Impacts of Select Pedestrian Infrastructure

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To enhance pedestrian safety at intersections, transportation agencies may install temporary or permanent infrastructure such as curb extensions or pedestrian refuge islands. While more permanent infrastructure with concrete is generally considered effective, specific details about temporary infrastructure with flexible delineators (or bollards), such as installation, use and safety impact, would be valuable to optimize cost-effectiveness. This project evaluated both temporary and permanent pedestrian infrastructure at crossing sites to measure the effects on pedestrian safety and driver behavior.

Continue reading Evaluating the Safety Impacts of Select Pedestrian Infrastructure →
research, Traffic and Safety

Pedestrian Safety Impacts of Dedicated Right-Turn Lanes

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While research has found that right-turn-only, or dedicated right-turn lanes, at intersections reduce traffic delays and vehicle crashes, their impact on pedestrian safety has been unclear. To better understand these impacts for future intersection design and countermeasure considerations, this project investigated driver response to pedestrians in or near crosswalks at dedicated right-turn lanes. 

Continue reading Pedestrian Safety Impacts of Dedicated Right-Turn Lanes →
research, Traffic and Safety

CTS Webinar: A New System to Report School Bus Stop-Arm Violations 

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Wednesday, December 10, 2025
11:30 a.m.–1:00 p.m. CST
Zoom Virtual

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About the Event

School bus stop-arm violations by motorists pose a serious risk to children. A new University of Minnesota study investigated the existing violation reporting ecosystem, finding issues like underreporting, underenforcing, and significant workflow inefficiencies and barriers across all stakeholder groups.

To address these systemic barriers, study researchers concluded that a centralized statewide online portal is needed to streamline communication, simplify data access, and standardize reporting. They also provided near-term recommendations until this comprehensive solution can be developed.

Join this webinar to learn about the research findings and proposed short- and long-term recommendations for improving the reporting system, with the goal of making bus stops safer for children across Minnesota and beyond

Continue reading CTS Webinar: A New System to Report School Bus Stop-Arm Violations  →
research, Traffic and Safety

Human behavior insights are driving transportation safety forward

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Reprinted from CTS News Catalyst, September 11, 2025

To better understand how roadway crashes can be prevented, it’s essential to explore the human behaviors that contribute to them. This objective is core to the work of the U of M’s Human Factors Safety Laboratory (HFSL). Research Associate Professor and CTS scholar Nichole Morris, who directs the lab, outlined its mission and impact in a recent Toward Zero Deaths (TZD) webinar highlighting Minnesota’s traffic safety research ecosystem. 

Minnesota TZD is the state’s cornerstone traffic safety program, employing an interdisciplinary approach to reducing traffic crashes, injuries, and deaths on the state’s roads. CTS partners with TZD to provide program administration, event coordination, and communications.

The HFSL brings together behavioral scientists and engineers dedicated to reducing roadway and occupational injuries and fatalities. They combine research on human behavior with the design and testing of user-centered systems to create solutions that work better for everyone.

“Human factors is the intersection between people and systems,” Morris explained. From in-vehicle technologies and roadway signage to partnerships with larger organizations such as law enforcement, transportation systems involve a wide range of human-system interactions.

Four research tracks shape the lab’s work:

  • Crash reporting. Although projects often intersect, crash reporting is foundational to the other research tracks. Morris refers to it as the lifeblood of transportation safety—without crash data, researchers don’t know what’s working and what isn’t. In one of its more consequential projects, the HFSL helped rebuild the front end of MNCrash—an application designed for law enforcement to document and report crashes. In close collaboration with the Minnesota Departments of Transportation and Public Safety as well as multiple law enforcement agencies, the HFSL team helped to streamline the user experience and improve data completeness and accuracy. Since deploying the updated version in 2016, MNCrash has been adopted by all law enforcement agencies across Minnesota. It’s featured in the sixth edition of the USDOT’s Model Minimum Uniform Crash Criteria and has become the national standard for crash reporting.
  • Maintenance and work-zone safety. In one project, leveraging the expertise and methods gained from MNCrash, the lab collaborated with MnDOT and maintenance workers on a streamlined app to make documenting work-zone intrusions easier. After its launch in 2022, the team continued work, using low-cost sensors and radar to help reduce select work-zone driving speeds in real time.
  • Pedestrian and non-motorist safety. The Stop for Me campaign, a collaboration with MnDOT, St. Paul, Ramsey County, and Western Michigan University, has been adopted in communities across Minnesota. The campaign—which combines enforcement and engineering treatments to improve yielding at crosswalks—has inspired similar efforts in more cities around the country. Other projects include studies on dedicated right-turn lanes and temporary and permanent pedestrian infrastructure to reduce conflicts between drivers and pedestrians.
  • Infrastructure and signage. The lab’s work on J-turns, which have proven effective at reducing fatal crashes, has helped to identify and address several navigational errors drivers may make when first encountering this type of intersection. The researchers have found that poor or confusing first experiences with J-turns can lead to negative community perceptions and result in pushback on J-turn implementation. The research has found specific pavement markings to help guide drivers and facilitate successful use of J-turns—leading to fewer crashes and better driver experiences.

Morris emphasized that investment in sound research methods and collaborations across partner institutions, organizations, and communities is what creates successful research outcomes. While studies may yield results in the moment, she says investing in methodology is what really carries the work forward. The HSFL’s work continues to inspire other states and agencies, Morris added.

—Krysta Rzeszutek, CTS digital editor

Related research from Nichole Morris

Traffic and Safety

Increasing School Bus Stop-Arm Compliance

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A significant number of school bus stop-arm violations occur every day throughout the country. In Minnesota, violation and citation data suggests these incidents are grossly underreported and underenforced due to a time-consuming reporting and enforcement process. This project examined current processes and recommended improvements to encourage higher rates of reporting and enforcement.

Continue reading Increasing School Bus Stop-Arm Compliance →