Effects of an integrated collision warning system on teenage driver behavior.

INTRODUCTION: Crash warning systems have been shown to provide safety benefits, but no studies have examined how teenagers respond. This study sought to find out whether young, inexperienced drivers change behavior in response to warnings. METHODS: Forty 16-17 year-olds drove an instrumented vehicle equipped with a system that warned for lane departures and potential rear-end and lane change/merge crashes. Participants were randomly assigned to experimental or control groups, and their driving was monitored for 14weeks during 2011-12. For the experimental group, this included a treatment period, when crash alerts were received by drivers, and baseline and post-treatment periods, when warnings were recorded but not received. The control group never received warnings. Data were analyzed to determine whether warnings were associated with changes in driving behavior. RESULTS: A total of 15,039 trips were analyzed. Lane drifts accounted for 73% of warnings. Forward collision warning rates doubled for all drivers during the treatment period and continued at an increased rate post-treatment. This was likely a result of the fact that, as time went on, all drivers spent more time following vehicles at close distances. Receiving alerts was associated with effects on following and lane-changing behavior, including more time spent following at close distances (17%), fewer lateral drifts (37%) and fewer unsignaled lane changes (80%). Receiving warnings wasn't associated with an increased likelihood of engaging in secondary tasks. CONCLUSIONS: Warning systems may result in improved lane-keeping and turn-signal behaviors by novice drivers, but there is some indication they may result in more close-following behaviors. PRACTICAL APPLICATIONS: There is some evidence that lane departure warning may improve turn-signal use for young drivers. While there is no evidence of safety benefits from the other types of warnings, there is some evidence of an increase in close-following behavior but no increase in secondary tasks due to the presence of those capabilities.

Distracting behaviors among teenagers and young, middle-aged, and older adult drivers when driving without and with warnings from an integrated vehicle safety system.

INTRODUCTION: Negative reinforcement from crash warnings may reduce the likelihood that drivers engage in distracted driving. Alternatively, drivers may compensate for the perceived safety benefit of crash warnings by engaging in distractions more frequently, especially at higher speeds. The purpose of this study was to examine whether warning feedback from an integrated vehicle-based safety system affected the likelihood that various secondary behaviors were present among drivers ages 16-17, 20-30, 40-50, and 60-70. METHOD: Participants drove an instrumented sedan with various collision warning systems for an extended period. Ten 5-second video clips were randomly sampled from driving periods at speeds above 25mph and below 5mph each week for each driver and coded for the presence of 11 secondary behaviors. RESULTS: At least one secondary behavior was present in 46% of video clips; conversing with a passenger (17%), personal grooming (9%), and cellphone conversation (6%) were the most common. The likelihood that at least one secondary behavior was present was not significantly different during periods when drivers received warnings relative to periods without warnings. At least one secondary behavior was 21% more likely to be present at speeds below 5mph relative to speeds above 25mph; however, the effect of vehicle speed was not significantly affected by warning presence. Separate models for each of the five most common secondary behaviors also indicated that warnings had no significant effect on the likelihood that each behavior was present. CONCLUSIONS: Collision warnings were not associated with significant increases or decreases in the overall likelihood that teen and adult drivers engaged in secondary behaviors or the likelihood of the behaviors at speeds above 25mph or below 5mph. PRACTICAL APPLICATIONS: There was no evidence that forward collision warning and other technologies like those in this study will increase or decrease distracted driving.

Using naturalistic driving data to examine drivers' seatbelt use behavior: Comparison between teens and adults.

PROBLEM: Teens and young drivers are often reported as one driver group that has significantly lower seatbelt use rates than other age groups. OBJECTIVE: This study was designed to address the questions of whether and how seatbelt-use behavior of novice teen drivers is different from young adult drivers and other adult drivers when driving on real roads. METHOD: Driving data from 148 drivers who participated in two previous naturalistic driving studies were further analyzed. The combined dataset represents 313,500 miles, 37,695 valid trips, and about 9500 h of driving. Drivers did not wear their seatbelts at all during 1284 trips. Two dependent variables were calculated, whether and when drivers used seatbelts during a trip, and analyzed using logistic regression models. RESULTS: Results of this study found significant differences in the likelihood of seatbelt use between novice teen drivers and each of the three adult groups. Novice teen drivers who recently received their driver's licenses were the most likely to use a seatbelt, followed by older drivers, middle-aged drivers, and young drivers. Young drivers were the least likely to use a seatbelt. Older drivers were also more likely to use seatbelts than the other two adult groups. The results also showed that novice teen drivers were more likely to fasten their seatbelts at the beginning of a trip when compared to the other three adult groups. SUMMARY: Novice teen drivers who were still in the first year after obtaining their driver's license were the most conservative seatbelt users, when compared to adult drivers. PRACTICAL APPLICATION: Findings from this study have practical application insights in both developing training programs for novice teen drivers and designing seatbelt reminder and interlock systems to promote seatbelt use in certain driver groups.

The conspicuity of first-responder safety garments.

INTRODUCTION: This study compared the conspicuity of three types of first-responder safety garments (NFPA 1971-2007 turnout gear coats, and ANSI/ISEA 107 and 207 safety vests). METHOD: Participants drove instrumented vehicles on a closed track during both daytime and nighttime, indicating when they could first detect pedestrians in a simulated emergency response scene. Pedestrians wore one of the safety garments and stood on either side of the emergency scene, facing or perpendicular to oncoming traffic, and either stationary or walking in place. RESULTS: All three garment standards provided equal levels of conspicuity, in that the distances at which the pedestrians were detected were equivalent. Time of day was a significant factor, with longer mean detection distances being observed in daytime. Pedestrian orientation was significant, with mean detection distances being longest when facing traffic. Pedestrian motion did not result in significant differences in detection distance. DISCUSSION: The results suggest that all three garment types studied are equivalent in making first responders conspicuous as pedestrians when working an emergency response scene in close proximity to traffic. IMPACT ON INDUSTRY: Whether an NFPA or ANSI/ISEA compliant is worn, first responders are equally likely to be detected by passing motorists, and as such these garments should be considered to be equivalent.

The roles of garment design and scene complexity in the daytime conspicuity of high-visibility safety apparel.

INTRODUCTION: This study examines the effects of high-visibility garment design on daytime pedestrian conspicuity in work zones. Factors assessed were garment color, amount of background material, pedestrian arm motion, scene complexity, and driver age. METHOD: The study was conducted in naturalistic conditions on public roads in real traffic. Drivers drove two passes on a 31-km route and indicated when they detected pedestrians outfitted in the fluorescent garments. The locations of the vehicle and the pedestrian were recorded. RESULTS: Detection distances between fluorescent yellow-green and fluorescent red-orange garments were not significantly different, nor were there any significant two-way interactions involving garment color. Pedestrians were detected at longer distances in lower complexity scenes. Arm motion significantly increased detection distances for pedestrians wearing a Class 2 vest, but had little added benefit on detection distances for pedestrians wearing a Class 2 jacket. DISCUSSION: Daytime detection distances for pedestrians wearing Class 2 or Class 3 garments are longest when the complexity of the surround is low. The more background information a driver has to search through, the longer it is likely to take the driver to locate a pedestrian--even when wearing a high-visibility garment. IMPACT ON INDUSTRY: These findings will provide information to safety garment manufacturers about characteristics of high-visibility safety garments which make them effective for daytime use.