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Work zones present an increased risk to drivers and the work crew. To mitigate these risks; this study investigated the potential effects of in-vehicle messages to communicate work zone events to the driver. The researchers conducted literature reviews on risks imposed by work zones; along with design guidelines for any in-vehicle messaging system. The researchers then conducted a work zone safety survey to illustrate driver attitudes in Minnesota toward work zones; along with smartphone use and in-vehicle messages through smartphones. The survey found that a significant number of drivers make use of smartphones in the automobile; and they placed these smartphones in various locations throughout the vehicle. The survey was followed by a driving simulation study that tested drivers in two different types of work zones. Participants drove through these work zones three times; each with different messaging interfaces to communicate hazardous events to the driver. The interfaces included a roadside; portable changeable message sign; a smartphone presenting only auditory messages; and a smartphone presenting audio-visual messages. There was better driving performance on key metrics including speed deviation and lane deviation for the in-vehicle message conditions relative to the roadside signs. Furthermore; drivers reported significantly less mental workload and better usability; work zone event recall; and eye gaze behavior for the in-vehicle conditions relative to the roadside sign condition.

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.

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.

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.

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.