729 research outputs found
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Cooperative Adaptive Cruise Control: Critical Human Factors Issues and Research Questions
No full textAs traffic volume and delay on highways increase each year, new solutions are required to meet travel demand and ease congestion. One possible solution, Cooperative Adaptive Cruise Control, permits vehicles and infrastructure to communicate, providing the capability to maintain safety while increasing travel lane capacity. The technical capabilities have been demonstrated, but as important to ensuring successful implementation is an understanding of the potential human factors-related issues. Use of automation in the driving environment can have numerous pitfalls, which are heavily influenced by a variety of both deliberate and reflexive human judgments and decisions known to be error-prone. This paper examines these potential issues and identifies research areas and questions that may guide future research to evaluate the safety, efficacy, and acceptance of this new technology
Effects of Environmental Factors on Naturalistic Driving in Obstructive Sleep Apnea
No full textReduced visibility and other environmental factors can impair driver ability to respond to roadway hazards. We examined the effects of reduced visibility on naturalistic driving in 66 drivers, including 45 at-risk drivers with obstructive sleep apnea (OSA) and 21 controls. We analyzed three months of electronic data using “black box” recorder technology and assessed the extent to which driver speed, longitudinal acceleration, and lateral acceleration metrics depend on ambient visibility from web-based environmental data archives. We calculated summary driving metrics within 10-second intervals, and reduced these to within-subject means and tested for associations of interest. OSA drivers did not differ from controls with respect to electronic measures or visibility conditions in which they drove. On average, drivers drove slower when visibility was reduced. After controlling for speed, variations in lateral and longitudinal acceleration were positively associated with high-visibility conditions. These findings suggest that drivers exert greater vehicular control when visibility is limited, and that this association is not just due to slower speeds. Weaker relationships between visibility and driving measures in OSA suggest reduced adaptive strategies. Our methods provide a framework for analyzing the effects of other environmental factors on driving, and we provide an additional example using wind speed
A Cohort-Based Data Structure Design for Analyzing Crash Risk Using Naturalistic Driving Data
No full textAlthough naturalistic driving studies (NDS) have become more prevalent in recent years, many challenges remain in analyzing the data. One challenge is inclusion of exposure in modeling crash risk. While this is a potential strength of NDS, comparatively few studies have emphasized exposure-based analyses. A second challenge is the formulation of analysis methods that include driver attributes, event attributes, and driving environment in a structured formulation. A third challenge is the formulation of baseline hazard to frequently accompany the identification of NDS "events" (e.g. crashes, near crashes and/or safety critical events). This paper reports on a cohort-based data structure design to address these three challenges. Collision warning alert frequency data from University of Michigan Transportation Institute (UMTRI)’s Roadway Departure and Curve Warning System (RDCW) Field Operation Test (FOT) are used to demonstrate this approach. The paper concludes with a discussion of applications which include crash and other NDS-observed events, including potential applications to road safety management through the development of enhanced safety performance functions
Distraction: Friend or Foe
No full textThe classic image in the psychology of driver-car interaction is that of a driver that wants to pay attention to the road: the job of designers is to avoid drawing the driver’s attention away from the road. A number of changes in drivers and cars makes this approach obsolete. Specifically, the following questions are pertinent: • Do drivers want to pay attention to the road? • Can drivers pay attention to the road? • Is attention/distraction the right metric for assessing the effects (positive or negative) of design? • How do new interfaces necessitate a change in our thinking about attention/distraction? • How do fully automated (autonomous) and partially automated vehicles necessitate a change in our thinking about attention/distraction? • How can interface design improve driver attention/performance (as opposed to merely reducing attentional demands)
Interactions between Cars and Motorcycles: Testing Underlying Concepts through Integration of On-Road and Simulator Studies
No full textWe conducted on-road and simulator studies to explore the mechanisms underpinning driver-rider crashes. In Study 1 the verbal protocols of 40 drivers and riders were assessed at intersections as part of a 15km on-road route in Melbourne. Network analysis of the verbal transcripts highlighted key differences in the situation awareness of drivers and riders at intersections. In a further study using a driving simulator we examined in car drivers the influence of acute exposure to motorcyclists. In a 15 min simulated drive, 40 drivers saw either no motorcycles or a high number of motorcycles in the surrounding traffic. In a subsequent 45-60 min drive, drivers were asked to detect motorcycles in traffic. The proportion of motorcycles was manipulated so that there was either a high (120) or low (6) number of motorcycles during the drive. Those drivers exposed to a high number of motorcycles were significantly faster at detecting motorcycles. Fundamentally, the incompatible situation awareness at intersections by drivers and riders underpins the conflicts. Study 2 offers some suggestion for a countermeasure here, although more research around schema and exposure training to support safer interactions is needed
Investigating the Effect of a Visual Search Task for Simulator-Based Driver Training
No full textNovice drivers tend to direct their gaze to the road ahead and not scan the environment properly. This study investigated the training effectiveness of a visual search task in a driving simulator, aimed at increasing young drivers' spread of visual search. Two groups of inexperienced drivers were instructed to drive as accurately as possible in the center of the right lane in a self-paced driving task of four 6-min sessions in a rural environment. While driving, one group performed a visual search task, consisting of detecting and fixating on visual stimuli in the peripheral area. The stimuli were purple dots that faded in slowly and disappeared when fixated by the participant. After training, both groups drove a transfer session in an urban environment, in which various hazardous situations occurred. Results showed that both groups improved their lane keeping performance, whereas the training group became more proficient in the visual search task. However, in the transfer session no group differences were detected. In conclusion, despite improvements in visual search performance during a relatively short training period, the visual search training did not detectibly influence the spread of visual search of novice drivers during a post training transfer session
Effectiveness of Bimodal Versus Unimodal Alerts for Distracted Drivers
No full textTwenty-two participants drove a simulated vehicle while engaged in a low or high working memory load task and responded to signals presented in auditory, visual and tactile modalities or their bimodal combinations by pressing on the brake. Signals were designed to be of low or high urgency in both unimodal and bimodal combinations. High urgency and bimodal signals were responded to faster than their low urgency and unimodal counterparts. Fewer bimodal signals were missed overall. This bimodal advantage was particularly significant relative to unimodal signals of low urgency in the high working memory load condition. Together these results indicate that hazard mapping can most effectively be obtained by designing with both the perceived urgency level of the signal and modal plurality in mind
Using Manual Measurements on Event Recorder Video and Image Processing Algorithms to Extract Optical Parameters and Range
No full textVehicle kinematics and optical parameters such as optical angle, optical expansion rate, and tau are thought to underlie drivers’ ability to avoid and handle critical traffic situations. Analyses of these parameters in naturalistic driving data with video, such as commercial event recordings of near-crashes and crashes, can provide insight into driver behavior in critical traffic situations. This paper describes a pair of methods, one for the range to a lead vehicle and one for its optical angle, that are derived from image processing mathematics and that provide driver behavior researchers with a relatively simple way to extract optical parameters from video-based naturalistic data when automatic image processing is not possible. The methods begin with manual measurements of the size of other road users on a video on a screen. To develop the methods, 20 participants manually measured the width of a lead vehicle on 14 images where the lead vehicle was placed at different distances from the camera. An on-market DriveCam Event Recorder was used to capture these images. A linear model that corrects distortion and modeling optics was developed to transform the on-screen measurements distance (range) to and optical angle of the vehicle. The width of the confidence interval for predicted range is less than 0.1m when the actual distance is less than 10m and the lead-vehicle width estimate is correct. The methods enable driver behavior researchers to easily and accurately estimate useful kinematic and optical parameters from videos (e.g., of crashes and nearcrashes) in event-based naturalistic driving data
Test-Retest Reliability of Simulated Driving Performance: A Pilot Study
No full textTwenty-seven volunteers completed three simulated driving tests to determine test-retest reliability of performance on a low-cost, fixed-base computerized driving simulator. One retest was completed a few hours after the initial drive, and the final retest was completed 7 days following the initial test drive. Driving performance was compared using measures of vehicle control, speed, and reaction time to critical events. A measure of participants’ ability to inhibit a pre-potent response was also assessed using an inhibition task during each drive, with the number of incorrect inhibition responses recorded. Practice effects were evident for measures of vehicle control (deviation of lane position and number of line crossings) and participants’ ability to withhold responses to inhibition tasks. Good test-retest reliability was observed for measures of vehicle control, speed, reaction time, and variability measures. Poor test-retest reliability was observed for the number of stopping failures observed during driving. The findings from this study suggest that the driving scenario used provides reliable assessment tasks that could be used to track the effects of pharmacological treatments on driving performance. However, an additional familiarization drive should be included as part of future study protocols employing this driving scenario to reduce learning effects during trials. Care should also be taken when interpreting results from tasks with low test-retest reliabilit
The Effect of Aging and Ground Texture on the Control of Braking
No full textIn the current study we examined age-related difference in the use of visual information in regulating braking. Younger and older drivers were presented with computer generated 3-D scenes simulating driving on a roadway towards three red stop signs at a constant speed. The task of the drivers was to control braking and to stop as close as possible to the stop signs. The texture density on the ground, initial time to contact (TTC) and initial distance from the stop signs were manipulated. We found that older drivers had larger mean stop distance and lower crash rate than younger drivers. In addition, older drivers, as compared to younger drivers, tended to regulate more frequently at values larger than -0.5 and less frequently at values smaller than -0.5. These results, taken together, suggest that older drivers may use a more conservative strategy to control braking in order to avoid collisions