Popular opinion has it that “road rage” is increasingly prevalent in the urban driving environment. Whether or not this opinion is true, driver frustration in congested conditions may lead to an increase in aggressive driving, a less malignant and more common subset of road rage. The potential for significant safety benefits might be realized if engineers had a better understanding of roadway factors and characteristics of the driving environment that induce irritation and contribute to aggressive driving. This report documents major activities: literature review, focus groups, telephone survey, and evaluation of three mitigation measures aimed at reducing driver stress that can lead to aggressive driving. Researchers evaluated the benefits of improvements at freeway bottlenecks. Feedback from commuters revealed that a majority realized reduced aggressive behaviors (e.g., preventing merge, cutting across solid lines, tailgating, etc.) and commute time after improvements were made at a bottleneck location in Dallas. Almost 50 percent also indicated an improvement in their personal stress level after the implementation of improvements. Operational data collected at this site such as increased volumes, speeds, and decreased queue lengths supported the feedback from commuter surveys. Secondly, researchers assessed the ability of photogrammetry to expedite clearance of incidents. Data from several police agencies suggested that photogrammetry could effectively reduce overall incident clearance time. Other data showed that photogrammetry compares very favorably in measurement accuracy to traditional investigation techniques. Finally, researchers tested the Late Merge concept developed in Pennsylvania at a work zone on Interstate 30 in Dallas. Merging at lane closures is the subject of considerable debate by drivers, the media, and even traffic engineers. The Late Merge concept is designed to encourage drivers to use all lanes approaching a lane closure and then take turns near the merge point by using several static signs in addition to normal work zone traffic control. The simulation laboratory and field tests revealed that the Late Merge concept is feasible on an urban freeway where three lanes are reduced to two. Further testing of this concept and other innovative merge strategies such as Early and Zip Merging is needed to determine the most efficient, safe, and least stressful method of encouraging merging at lane closures. (Author/publisher)
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