Browsing by Author "Bloomfield, John R."

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    Comparison of Dual-Phase and Static Changeable Message Signs to Convey Airline Information on Interstate Freeways
    (Minnesota Department of Transportation Research Services Section, 2010-01) Harder, Kathleen A.; Bloomfield, John R.
    We used a fully interactive PC-based STISIM driving simulator to compare dual-phase Changeable Message Signs (CMSs) and static CMSs. The participants were 120 licensed drivers from three age groups: 18-24, 32-47, and 55- 65 years of age. They drove eleven miles on a simulated six-lane highway towards an airport, knowing which airline to look for. Airline information was provided on two separate CMSs located 500 ft (152.4 m) apart on the highway in one condition, or on a single dual-phase CMS in the other condition. The participants took the correct exit on 89.6% of the drives (215 of 240). There were no statistically significant differences between the number of participants who failed to take the correct exit in the dual-phase and the static CMS conditions. On the approach to the CMSs displaying airline information, there were significant differences in average speed between the three age groups—younger drivers drove faster than middle age and older drivers. However, average speeds were not different in the dual-phase and static CMS conditions. Some individuals reduced speed on approaching the CMSs—suggesting similar reductions could occur in real world driving in free flow conditions. There were no differences in the number or magnitude of the speed reductions for the dual-phase and static CMS conditions. In this experiment, displaying airline information on a single dual-phase CMS was as effective in influencing driving behavior as displaying the same airline information on two static CMSs.
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    The Effectiveness and Safety of Traffic and Non-Traffic Related Messages Presented on Changeable Message Signs—Phase II
    (Minnesota Department of Transportation, 2008-08) Harder, Kathleen A.; Bloomfield, John R.
    In Phase II of this investigation, we used a fully interactive PC-based STISIM driving simulator, to conduct two experiments which were similar to experiments in Phase I. The participants were 120 licensed drivers from three age groups—18-24, 32-47, and 55-65 years old—who drove, in free flow traffic, for approximately 20 miles on a four-lane freeway before encountering target messages on Changeable Message Signs (CMSs). The Phase II CMS messages were clearer and less complex than those used in Phase I. In the first experiment the target message was changed to “Road Closed/Crash Ahead/Use Thompson Exit:” 93.3% of the participants took the exit—as compared to 55.8% in Phase I. In the second experiment, the message was changed to “Abducted Child/Tune To/Radio 88.5 FM:” 71.7% of the participants (71.7%) could remember enough information to enable them tune to 88.5 FM—as compared to 8.3% who could recall some vehicle information and at least five license plate letters and numbers from the Phase I CMS (“AMBER Alert/Red Ford Truck/ MN Lic# SLM 509”). Some participants reduced speed on approaching the CMSs, suggesting similar reductions could occur in real world driving in free flow conditions. However, when traffic is congested speeds are typically slower, and drivers are less likely to reduce speed still further to read CMSs. We conducted a survey which showed drivers think it is very useful to have information about traffic problems and roadway maintenance schedules on CMSs. Also, we analyzed real-world traffic speed data obtained when CMS messages were deployed. Finally, we conducted observations at Mn/DOT’s Regional Transportation Management Center (RTMC), focusing on the decision-making processes involved when traffic-related CMS messages are deployed.
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    Evaluating the Effectiveness of the Minnesota Speed Management Program
    (Minnesota Department of Transportation, Office of Research Services, 2007-05) Harder, Kathleen A.; Bloomfield, John R.
    The Minnesota Speed Management Program (MSMP), a cooperative project between the Minnesota Department of Transportation and the Minnesota Department of Public Safety, was developed within the framework of the Minnesota Comprehensive Highway Safety Plan. The overall goal was to reduce the number of fatal and life-changing crashes on Minnesota highways. The MSMP involved a speed limit adjustment; on 850 miles of Minnesota's 55 mph highways the speed limit was increased to 60 mph. It involved increased speed enforcement--by State Patrol, county sheriffs, and local law enforcement--on selected highways. There were four waves of Enhanced Enforcement (one of six weeks, three of eight weeks) each followed by four weeks of Regular Enforcement. The MSMP involved extensive public education, organized by the Office of Traffic Safety, with approximately 10,000 public service messages presented on the radio. Two evaluation efforts were conducted. The University of Minnesota compared travel speed data and crash data obtained during the MSMP with historical data. Throughout the MSMP, there were decreases in the number of drivers traveling at least 10 mph above the speed limits: decreases of -28.7% on 2-Lane/2-Way Highways; -28.7% on 4-Lane Divided Highways; -42.9% on Rural Freeways; and -11.2% mph on Urban Freeways. The University's evaluation also showed there were reductions in the numbers of fatal and life-changing crashes during the MSMP. MarketLine Research conducted the second evaluation, using telephone surveys, and found nine in ten drivers support the speed limit increase from 55 mph to 60 mph in both Metro and Greater Minnesota. The MSMP, in concert with other efforts that are part of the Minnesota Comprehensive Highway Safety Plan, resulted in reductions in the number of speeders on Minnesota Highways and reductions in the number of fatal and life-changing crashes, making Minnesota's roads safer.
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    Investigating the Effectiveness of Intelligent Lane Control Signals on Driver Behavior
    (Minnesota Department of Transportation, 2012-08) Harder, Kathleen A.; Bloomfield, John R.
    A fully interactive PC-based STISIM driving simulator was used to test the effectiveness of Intelligent Lane Control Signals (ILCS). The participants were 160 licensed drivers from four age groups: 18-24, 32-47, 55-65, and 70+ years of age. Each participant drove three times in a counterbalanced order. In each trial, after driving five miles in the center lane of a six-lane highway where the speed limit was 65 mph, they encountered five sets of ILCSs that occurred at half-mile intervals. These ILCSs presented (1) 45-mph speed limit messages; (2) 35-mph speed limit messages; (3) a yellow lane closure warning; (4) one of three merge messages that used a diagonal arrow, or words, or dynamic chevrons to indicate that drivers should move from the center lane; (5) a red lane closure warning. Analysis of lane position data showed that the diagonal arrow merge sign was the most effective; participants moved from the center lane 266 feet before reaching the diagonal arrow merge sign, 123 feet before reaching the dynamic arrow merge sign, and 54 feet before the merge sign with words. Analysis of driving speed data indicated that the speed limit signs were effective. Before the 45-mile speed limit was visible, participants drove at 63 mph. When the 45-mph speed limit was visible, they reduced speed by approximately 10 mph. Then on the approach to the 35-mph speed limit, they reduced speed by a further 14 mph—on average, they were driving at 38.7 mph shortly after passing the 35-mph speed limit.
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    Psychological and Roadway Correlates of Aggressive Driving
    (University of Minnesota Center for Transportation Studies, 2008-12) Harder, Kathleen A.; Kinney, Terry A.; Bloomfield, John R.
    This study was conducted to better understand the psychological and roadway correlates of aggressive driving. The study had two phases: In Phase One, survey data was used to investigate the relationship between personality, emotional, and behavioral variables and self-reported driving behavior—710 people were surveyed. In Phase Two, 67 participants (35 classified as high hostile—those with the most extreme high hostility survey scores—and 32 classified as low hostile—those with the most extreme low hostility survey scores) drove for 19-miles on a simulated four-lane freeway. The data yielded a number of interesting findings; in particular, there were significant differences in driving behavior between drivers characterized as high hostile and those characterized as low hostile. For example, when drivers in the high hostility group were blocked by other vehicles, they responded by driving much closer to the blocking vehicles than drivers in the low hostility group. This risky driving behavior, found in a driving simulator, validates the self reports given by the high hostile drivers in the surveys. This finding is likely to be of value for public safety organizations whose mission is to educate the public about potentially dangerous and risky behavior. It is not likely that all those who are classified as high in hostility will engage in aggressive driving behavior. Further research may yield additional understanding on this point.
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    Stopping Behavior at Real-World Stop-Controlled Intersections with and without In-Lane Rumble Strips
    (Minnesota Department of Transportation, 2006-11) Harder, Kathleen A.; Bloomfield, John R.; Chihak, Benjamin
    This was the third in a series of studies investigating various aspects of rumble strips. In this study, to determine the effect of rumble strips on the real-world stopping behavior of drivers, we used a radar gun to collect speed data from over 400 vehicles on the approaches to ten intersections selected from a sample of 274 approaches. We found that, after drivers encountered the first set of in-lane rumble strips, they slowed down earlier on real-world approaches With Rumble Strips than on real-world approaches Without Rumble Strips—the difference was, on average, 2.0 mph to 5.0 mph (depending on vehicle category and type of approach). In addition, speeding outliers were more likely to slow down earlier on approaches With Rumble Strips. The effect of the presence of in-lane rumble strips on stopping behavior was greater for approaches where the driver’s view of traffic on the major road is obscured on one or both sides of the road. The study suggests that stop-controlled intersections at which cross-traffic is obscured by manmade structures and/or vegetation on one or both sides of the intersection would be good candidates for implementing in-lane rumble strips. It is worth noting that while in-lane rumble strips are likely to reduce crashes, they cannot eliminate them. Some drivers might still run stop signs and others might misjudge gaps.