Work zones are a vital component of our transportation infrastructure; however, they pose a threat to motorists, workers, and law enforcement due to a wide range of complex issues. Each year, over 100 road construction workers in the U.S. are killed in work zones (NSC, 2011). Furthermore, in 2013, there were 579 work zone, fatal motor vehicle crashes in the U.S. (FARS, 2013). Driver inattention contributes to approximately half of all work zone crashes and worker strikes (NSC, 2011). More work can be done to develop countermeasures against work zone crashes, especially those resulting from inattention. Experts from the Minnesota Departments of Transportation, Department of Public Safety, and State Patrol were surveyed to examine which aspects of work zones present the most concern for safety. Respondents reported that factors that drivers may not expect such as lane closures, maintenance work zones, and high traffic volumes present the most external threats to safety in work zones. The experts also indicated that distraction, speeding, and aggressive driving are the most risky driving behaviors, with older and younger drivers being the driving groups that most often threaten safety in work zones. When asked about which interventions have the greatest short- and long-term influence on speed reductions in work zones, respondents overwhelmingly reported traditional law enforcement was the most effective, and automated speed enforcement (ASE) was the least perceived effective method. A comprehensive examination of research conducted in other states and countries with ASE, however, clearly indicate a strong effect of ASE in reducing speed, serious injury and fatal crashes. The purpose of this study was to investigate the impact of different types of speed enforcement methods on driver attention in work zones. The investigation not only examined enforcement methods currently used in Minnesota, but also examined how implementing ASE, which is not currently used in Minnesota, may influence driver attention and behavior in work zones. While a substantial body of work exists regarding the efficacy of ASE in work zones and other roadways, it is unknown how ASE compares with other speed limit enhancements (e.g. speed display signs, high visibility traditional law enforcement, etc.) in terms of its impact on driver attention and distraction. Overall, the proposed research plan examines how drivers respond to four types of enforcement at work zones: control (no enforcement), police car present, dynamic “your speed” signs, and ASE. The experiment uses a simulated work zone on a realistic rural divided Minnesota roadway, Hwy 169 between Jordan, MN and Belle Plaine, Minn. The aim of this study was to determine whether drivers respond to various types of speed limit enhancements differently with regard to speed limit compliance, safe following distances, crash rates, lane control, visual attention, and distraction seeking. Overall, the results do not strongly support the hypothesis that ASE without dynamic speed display sign (DSDS) improves driver attention in work zones. There is some evidence, however, that drivers heighten their visual attention in work zones with ASE+DSDS Enforcement. Drivers fixated on the secondary task display less frequently in the ASE+DSDS condition compared to other enforcement types while they traveled in the downstream portion of the work zone. This may suggest a time and distance halo of visual attention to the primary task of driving when drivers are monitored with ASE+DSDS. Finally, drivers do engage in more glances to their speedometer in the ASE+DSDS work zones compared to ASE only, but they do not appear to be overly occupied with this monitoring since they do not monitor their speedometer significantly more often compared to when police are present or under no enforcement conditions. The largest effects of the study were found among the age groups, with Young and Older Drivers exceeding the speed limit most often and varying their speed slightly depending on the type of enforcement present. Middle-aged drivers exhibited the greatest speed control and tended to abide by the speed limit to the same extend regardless of the type of enforcement present. Exerting this control may have contributed to their higher reported mental effort. Young and Older drivers are the most at-risk age groups in work zones, and they appear to be most positively influenced by ASE+DSDS. (Author/publisher)
Abstract