Browsing by Author "Dunn, Naomi"
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- A Case Study Approach to Understand Heavy Truck Safety-critical Events in Work ZonesDunn, Naomi; Soccolich, Susan; Hickman, Jeffrey S. (National Surface Transportation Safety Center for Excellence, 2022-08)Large trucks are overrepresented in work zone crashes. Data from the Federal Motor Carrier Safety Administration’s Large Truck and Bus Crash Facts show that, in 2017, 30% of work zone fatal crashes and 12% of work zone injury crashes involved at least one large truck, which was more than double the percentage of all crashes that occurred outside of work zones, where 12% of fatal crashes and 5% of injury crashes involved at least one truck. This study used data from four major truck naturalistic driving studies to investigate the risk associated with a variety of work zone roadway, environmental, and safety features. The vast majority of the work zone observations occurred with no adverse weather conditions present, dry road conditions, straight roadway alignment, and light traffic, with roughly three-quarters of commercial motor vehicle (CMV) drivers wearing a seatbelt. The most common features observed in work zones were warning signs, barrel barriers, and lane closures, which were used in various combinations. Traffic cones were associated with an increase of safety-critical event (SCE) risk, likely as a result of their small size and being less visible to CMV drivers. Reflective signs, barrels, and concrete barriers, however, reduced the SCE risk for CMV drivers in work zones by 40%–60%. There was a small decrease in SCE risk associated with light traffic in a work zone compared to moderate and heavy traffic. There was also a nearly 3-times greater risk of a CMV driver being involved in an SCE in work zones on single-lane roadways versus four-lane roadways. Active work zones had nearly twice the SCE risk for CMV drivers compared to inactive work zones. In active work zones, non-driving-related distractions, internal distractions, and external distractions all resulted in an almost three-fold increase in SCE risk for CMV drivers. When planning smaller, more temporary work zones, it may be beneficial for worker and road user safety if planners employ larger, more visible safety barriers such as barrels and reflective signage.
- Rocky Mountain Naturalistic Driving StudyDunn, Naomi; Viray, Reginald (National Surface Transportation Safety Center for Excellence, 2024-06-17)The Rocky Mountain Naturalistic Driving Study (RMNDS) was, at the time of data collection, the first attempt to use the NDS methodology to conduct research on the effects of cannabis on driving performance. The resulting dataset comprises over 14,000 trips made by 23 participants who self-reported medium to heavy cannabis use and who also reported they had a history of driving under the influence of cannabis. A unique aspect of the study was the collection of quantitative and qualitative drug use data. Qualitative drug use data was collected via an online journal, while quantitative drug use data was collected using a Quantisal oral fluid collection device prior to one driving trip each week. Samples were sent to a toxicology laboratory for analysis, which produced quantifiable test results for the National Institute on Drug Abuse 5 drug panel, including delta-9-THC. Out of the 14,000+ trips, there were a total of 178 verified drug test results along with 1,549 drug use journal entries. While the study proved successful for collecting naturalistic driving data and both objective and subjective drug use data, the difficulty comes in linking the drug use data to the driving data in order to identify periods of driving that may be impacted by the consumption of cannabis and/or other drugs. Further analysis of the RMNDS data, including identification of trips linked to drug use, would provide invaluable information about the impact of cannabis and/or other drugs on driving performance.