Morris, Nichole L.

As more automated vehicles enter shared roadways, an essential aspect of automated vehicle (AV) safety is understanding the interactions between these vehicles and other road users. Anecdotal incidents about aggressive following and overtaking behaviors at crosswalks near the Med City Mover (MCM), a low-speed automated shuttle (LSAV) pilot demonstration in Rochester, MN, suggested the need for a scientific study of the behaviors of drivers of manual vehicles near the LSAV. In this report, the research team conducted a series of laboratory and field studies aimed at better understanding the safety relationship between LSAVs and the humans with whom they share the road. Overall, the studies found an increased risk of overtaking and multiple threat passing near the MCM, which may increase the risk of pedestrian-involved crashes, sideswipe crashes, and rear-end crashes. Study findings suggested that poor human-machine interfaces, exceptionally slow vehicle speeds, and resultant large queues behind the MCM contribute to these risks. Improved communication interfaces, speeds more consistent with the surrounding traffic, and smaller queue size will be important factors that AV developers and future pilot demonstrations must consider to better promote pedestrian safety near AVs.

This flyer was created as part of Report 2023-04, "Development of a Mobile App for Reporting Work Zone Intrusions," published January 2024.

Work zone intrusions represent a significant safety risk to workers. To help better understand these situations, the Minnesota Department of Transportation partnered with the University of Minnesota to create a method to document intrusion events. This information provides a deeper understanding of the circumstances under which these events occur and enables data-driven decision making when considering ways to reduce or mitigate work zone intrusions. This work focuses on the development of a mobile smartphone app that allows workers to report intrusions from the field immediately after they occur, allowing for timely and accurate intrusion reporting. The work zone intrusion mobile app is developed using an iterative, user-centered design process that solicits feedback from work zone personnel, supervisors, and work zone safety stakeholders at every step in the process. The app uploads completed report data to the existing eSAFE system, allowing for a single repository of collected intrusion report data. To support deployment of the system, training workshops and supporting training and communications materials are created for distribution among users. Throughout the development and deployment of the app, user feedback shows that the app is easy to use and well liked.

A novel infrastructure design known as the J-turn intersection reduces the risk of serious and fatal crashes at thru-STOP intersections through decreasing points of conflict at an intersection by restricting crossing movements from the minor road. Despite their demonstrated safety efficacy, J-turns have not been met with uniformly positive support. In this research, we first examine novice driver baseline attitudes and driving behaviors on J-turns using a driving simulator study. Results demonstrate that critical errors are decreased with driving exposure to the J-turn; however, attitudes toward J-turns are not improved by exposure alone. A series of studies then evaluates the efficacy of various messaging strategies and educational materials on improving attitudes toward J-turns. The findings from these studies identify that the use of both educational materials and persuasive and customized messaging strategies is an effective method for increasing acceptance of J-turns across diverse resident populations (i.e., rural, suburban, and urban) and among stakeholders in Minnesota. This work demonstrates the importance of the role of proactive educational programs and community initiatives in promoting the acceptance and buy-in toward novel roadway treatments, such as J-turns, among diverse drivers, communities, and stakeholder groups.

Snowplow operators are often tasked with clearing snow from roadways under challenging conditions. One such situation is low visibility due to falling or blowing snow that makes it difficult to navigate, stay centered in the lane, and identify upcoming hazards. To support snowplow operators working in these conditions, University of Minnesota researchers developed a snowplow driver-assist system that provides the operator with visual and auditory information that is suitable for low-visibility situations. A lane-guidance system uses high-accuracy Global Navigation Satellite System (GNSS) and maps of the roadway to provide information to drivers about their lateral positions. A forward-obstacle-detection system uses forward-facing radar to detect potential hazards in the roadway. The design of the system, and in particular its interface, is guided by extensive user testing to ensure the system is easy to understand, easy to use, and well liked among its users. The system was deployed in two phases over the 2020-2021 and 2021-2022 winter seasons. In total, nine systems were deployed on snowplows across Minnesota, four in the first winter season and an additional five in the second. Participating truck stations represented all eight MnDOT districts as well as Dakota County. Over the course of the deployment, additional user feedback was collected to identify system strengths and areas for improvement. The system was found to be a cost-effective addition to snowplows that increase driver safety, reduce plow downtime, and increase driver efficacy for plowing operations, thus providing support to operators working in demanding, low-visibility conditions.

Flaggers protect workers by providing temporary traffic control and maintaining traffic flow through a work zone. They are often the first line of defense to stop distracted, inattentive, or aggressive motorists from intruding into the work area. This project aims to develop an automated intrusion detection system to alert drivers who are unsafely approaching or entering a flagger-controlled work zone. A human factors user needs assessment found maintenance workers preferred a modified traffic signal to feature the alert system due to flagger risks of being in the roadway and drivers failing to stop and remain stopped when presented with the STOP side of the flagger sign. A modified traffic signal that could be operated using a handheld remote was developed. The low-cost embedded electronics on the traffic signal enabled it to track trajectories of nearby vehicles, detect potential intrusions, and trigger audio-visual warnings to alert the intruding driver. Usability testing in a simulated driving test found poor expectancies and stopping rates of the traffic signal-based alarm system compared to a traditional flagger but did demonstrate evidence that drivers may be less likely to stop and remain stopped with the flagger STOP sign than the red ball indicator of the traffic signal. Furthermore, some drivers corrected their initial stopping error after triggering the auditory alarm of the traffic signal. A follow up test found improved performance with the alert system incorporated into an audiovisual enhanced STOP/SLOW flagger paddle. Testing of the developed sensor system found the system capable of simultaneous multi-vehicle tracking (including estimation of vehicle position, velocity, and heading) with a range of up to 60 meters and angular azimuth range of 120 degrees and correctly detecting all test intruding vehicles.

Pedestrian deaths are at a 30-year high nationally, accounting for 16% of total deaths in 2018 and far exceeding the previous decade of 12%, a trend mirrored in Minnesota. Previous research found an increase in local and citywide yielding at unsignalized crosswalks following an engineering and high-visibility enforcement program in Saint Paul, Minnesota. This study examined a modified engineering-focused (i.e., without enforcement) program expanded to both unsignalized and signalized intersections across the Twin Cities. The six-month study found modest improvements in yielding from baseline to treatment end (48.1% to 65.5% in Saint Paul and 19.8% to 38.8% in Minneapolis) at unsignalized engineering treatment sites but no improvements at generalization sites. No significant improvements in left- or right-turning yielding by drivers in Saint Paul were found at treated signalized intersections, but given that yielding was significantly worse at generalization sites over time, there may be some evidence that treatments mitigated performance declines among Saint Paul drivers during the study period. Yielding improvements at signalized treatment sites were more pronounced for only right-turning drivers in Minneapolis, but generalization sites showed no improvement or even worsened over time. Overall, study results suggested no shift in driving culture in either city, as found with the previous study using police enforcement, but found some evidence of local, site-specific changes in driver yielding behavior at treatment locations.

Teenage drivers are at a disproportionate risk of fatal and serious injuries due to motor vehicle crashes. A Field Operational Test (FOT) funded by MnDOT used the Teen Driver Support System (TDSS) smartphone application to collect real-time driving performance data from a cohort of approximately 300 teen drivers, recruited in early 2013, who were monitored over a 12-month period after licensure. Study results showed the TDSS application's success in reducing instances of speeding for the two groups that received feedback, compared to teens who received no coaching or parental involvement, was influential in reducing kinematic driving events, e.g., hard braking. This five-year follow-up investigation of the long-term outcomes of the TDSS FOT cohort aimed to determine the frequency of state-recorded traffic citations and crashes along with these drivers' self-reported driving behaviors and attitudes. Of the original cohort, 251 agreed to be contacted for future studies and 150 were successfully recruited into the follow-up study. A re-examination of the FOT risky driving distributions divided into tertiles (low, moderate, high) found overdispersion of control group teens in the high risky tertiles compared to the two TDSS intervention groups, particularly for speeding-related behaviors and texting. The tertile risk level of early risky driving (e.g., speeding, hard braking) was found to significantly predict long-term safety outcomes for traffic violations/tickets. However, the sample size for crashes among the over sample was too small to determine if the mediating effect of the TDSS on early risky driving resulted in long-term reductions in crashes.

Decisions made regarding driver sight distance at rural intersections are complex and require considerations for safety; efficiency; and environmental factors. Sight distance; cross-traffic velocity; and vehicle placements significantly affect driver judgment and behavior at these intersections. A series of rural; two-lane thru-STOP simulated intersections with differing sight distances and traffic speeds were created and then validated by county and state engineers. Experimental data from 36 participants in a time-to-collision (TTC) intersection crossing judgment task and a rural highway thru-STOP intersection driving simulation task was analyzed to clarify the influence of rural thru-STOP intersection characteristics on driving performance and decision-making. Results demonstrated that longer sight distances of1;000 ft. and slower crossing speeds (i.e.; 55 mph) were more accommodating for participants attempting to select gaps and cross from the minor road; corresponding with (1) lower mental workload; perceived risk; difficulty; and anxiousness; and (2) better performance in terms of estimated crash rate; and larger TTCs. Second; longer distances of 1;000 ft. appear to aid drivers' responsiveness on the main road approaching an intersection; specifically when another driver on the minor road runs the stop sign. Minor road drivers positioned close to the roadway at the stop sign; compared to standard stop bar placement; tended to help reduce the speed of main road drivers. Overall;results demonstrated a systematic improvement in the performance of both minor and major road drivers with the implementation of a1;000-foot sight distance at rural thru-STOP intersections.

sed a multifaceted approach to improving compliance to the Minnesota crosswalk law in Saint Paul; Minnesota; including: (1) education; (2) measurement; (3) enforcement efforts; (4) social norming; and (5) engineering treatment. The multifaceted activities were planned and implemented in Saint Paul with city traffic engineers and enforcement officers. The study initially observed 32% yielding and frequent multiple threat passing at 16 unsignalized; marked crosswalks throughout Saint Paul; measured through staged pedestrian crossings by the research team. A program was implemented that used a phased treatment approach of disseminating educational materials; conducting four waves of high visibility enforcement (HVE); displaying yielding averages on feedback signs across the city; and introducing low-cost engineering solutions through in-street signs. The results demonstrated a significant impact from education; HVE; and engineering to increase yielding to as high as 78% at enforcement sites and 61% at untreated sites. Multiple threat passing was also reduced. Overall; the study demonstrated that the HVE program and combined low-cost engineering were effective at improving compliance to the crosswalk law.