Browsing by Author "Tian, Disi"

Now showing 1 - 6 of 6
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    Establishing a Repeatable Method for Presenting Nontraditional Traffic Treatments to Maximize Stakeholder Support
    (Minnesota Department of Transportation, 2023-08) Morris, Nichole L.; Schwieters, Katelyn R.; Craig, Curtis M.; Tian, Disi
    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.
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    In-Vehicle Work Zone Messages
    (Minnesota Department of Transportation, 2017-06) Craig, Curtis M.; Achtemeier, Jacob; Morris, Nichole L.; Tian, Disi; Patzer, Brady
    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.
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    Multi-city study of an engineering and outreach program to increase driver yielding at signalized and unsignalized crosswalks
    (Minnesota Department of Transportation, 2023-03) Morris, Nichole L.; Craig, Curtis M.; Drahos, Bradley; Tian, Disi; Van Houten, Ron; Mabry, Marshall; Kessler, William
    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.
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    Multidisciplinary Investigation Of Rural Intersection-Related Crashes And Crash Injuries: Characteristics, Risk Factors And Prevention
    (2021-06) Tian, Disi
    Introduction: Rural intersections disproportionally contribute to crashes in rural United States (U.S.). Few available studies have examined potential causal associations between important intersection-relevant exposures and crash outcomes. Additionally, the efficacy of an advanced Rural Intersection Conflict Warning System (RICWSs), implemented at high-risk rural two-way stop-controlled intersections, has been largely unknown. Methods: This multidisciplinary study included: 1) an ecological epidemiologic analysis to identify the magnitude of and risk factors for rural intersection-related crash rates (per 100 million Annual Average Daily Traffic — AADT) by the level of injury severity, among various intersection characteristics; 2) a quasi-experimental epidemiologic investigation to evaluate the efficacy of the RICWSs for crash reductions, among 56 intersection risk-sets, each containing one RICWS treatment and three relevant control intersections; and 3) a driving simulator study to evaluate how different RICWS designs impacted drivers’ behaviors among 120 participants. The study population involved a representative sample of rural intersections in Minnesota (n = 4,172). Adjusted crash rate-ratios were obtained from the Generalized Estimating Equations (GEE), while adjusting for relevant confounders. Potential causal associations between RICWSs and various crash rate outcomes (per intersection per year) were determined, using Difference-in-Difference (DID) and Difference-in-Difference-in-Difference (Triple-D) analytical methods. Various regression models, applying the GEE, enabled efficacy determination of each RICWS design and an aggregated RICWS treatment effect, averaged across all simulated RICWS designs, among different levels of drivers' ages, mainstream traffic volume, and intersection visibility. Results: Rural intersection-related crash rates were significantly associated with various important intersection relevant risk factors by the level of injury severity. Minnesota RICWSs demonstrated a potential significant protective effect against targeted right-angle crashes, continuously, over time, post-treatment (p < 0.05). The original RICWS design potentially improved gap acceptance performance among drivers; however, it also increased the risk of stop-sign violations (Risk Ratio = 2.2, 95% Confidence Interval (CI) = 1.03 to 4.64). Conclusions: This study serves as a basis to provide insight into prioritizing the prevention of rural intersection-related crashes and associated injuries. It has significant research relevance to mitigate the overall mortality and morbidity of motorists, including the working population, on the U.S. rural roads.
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    Rural Intersection Conflict Warning System Evaluation and Design Investigation
    (Center for Transportation Studies, University of Minnesota, 2018-05) Tian, Disi; Morris, Nichole L.; Libby, David A.
    The Rural Intersection Collision Warning System (i.e., RICWS) has been deployed across the state of Minnesota to provide real-time traffic information to motorists to assist them with identifying sufficient vehicle gaps at thru-STOP intersections. However, since its implementation, a number of complaints have been received from local road users in regard to the signs. To identify the human factors issues with the current RICWS sign and to propose safe and efficient alternatives to its use, multiple rounds of usability tests were conducted with Minnesota county engineers and local road users to assist iterative design modifications as well as evaluate the effectives of each sign’s ability to accurately convey information regarding each of its three states. Three alternative design options were developed and tested along with the original RICWS sign via a driving simulator. A total of 120 participants, including novice teenage drivers (16-18 years old), middle-aged drivers (35-50 years old) and older drivers (65-77 years old), were recruited and were then asked to drive through a sequence of rural thru-STOP controlled intersections, with and without the intervention. The objectives were to evaluate the safety effectiveness and efficiency of different RICWS sign options to promote safe gap acceptance at different types of rural intersections (i.e., varying levels of mainstream traffic volume and intersection visibility). The research findings revealed an overall safety benefit of the intervention; however, potential risks were also identified associated with its deployment. It was also observed that drivers’ perceptions did not all match their actual driving behaviors.
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    Simulated driver performance, error, and acceptance study of a J-turn intersection with 3 levels of signage
    (2024-01-08) Morris, Nichole L; Schwieters, Katelyn R; Tian, Disi; Craig, Curtis M; nlmorris@umn.edu; Morris, Nichole L; University of Minnesota HumanFIRST Lab
    Thirty-six participants with limited previous experience and knowledge of J-turn intersections participated in a simulation study to examine their acceptance of J-turns and left turning navigational performance at three simulated J-turn intersections in counterbalanced order, each featuring one of three signage levels (minimum, intermediate, and full). Participants navigational path was visualized and scored for error occurrence by 3 raters/coders. Eleven different error types occurred and they were classified as minor, moderate, or major severity errors. Participants provided demographic information, crash history, and acceptance of J-turn intersections (across three scales) before and after driving through the simulated J-turn intersections. The data has been deidentified and is available to provide a better understanding of common errors from drivers who are experiencing J-turn intersections for the first time and the resultant influence that their error experiences have on their acceptance of the novel intersection design.