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The Quality of Behavioral and Environmental Indicators Used to Infer the Intention to Change Lanes
Get PDFThis study focuses on the examination and comparison of selected behavioural and environmental indicators that predict the intention to change lanes. These indicators were chosen from previous driving studies and driver models. The data were gathered in a field study with an instrumented car that can log data from the driver, the car, and the environment. The collected data were analysed and modelled with the help of a “knowledge discovery framework” (Georgeon, Mille, & Bellet, 2006). The first analysis of all lane changes caused by a slow leading vehicle focuses on the following indicators: glance to the left outside mirror, turn signal, and lane crossing. It is shown that the glance to the left outside mirror could serve as a predictor with a high potential to get information about the intention to change lanes in a very early stage. However, it is important to combine this predictor with additional predictors to avoid a high false alarm rate
Awareness of Performance Decrements Due to Distraction in Younger and Older Drivers
Get PDFAlthough many studies have documented the performance decrements associated with driver distractions, few have examined drivers’ awareness of these distraction effects. The current study purports to measure how wellcalibrated drivers are with respect to their own performance when distracted. Forty drivers completed a series of tasks on a hand-held or hands-free cell phone while driving an instrumented vehicle around a closed test track. Subjective estimates of performance decrements were recorded and compared to actual decrements observed on multiple measures of driving performance. Although their driving performance suffered in dual-task conditions, drivers were generally not well-calibrated to the magnitude of the distraction effects (r = -.38 to .16). In some cases, estimates of distraction were opposite of the observed effects (i.e., smaller estimates of distraction corresponded to larger performance deficits). There were some age and gender differences. We discuss the implications of these findings for potential mitigation strategies for distracted driving
The Relationship Between Driving Behavior and Entropy
Get PDFOBJECTIVES High variability in the lateral control of a vehicle may result in an increased likelihood of accidents. Boer (2000) proposed a method of quantifying variability in steering wheel position, termed “entropy” (scaled between 0 and 1). In this approach, the steering wheel position at each time point is predicted based on the position at the three preceding time points, and the discrepancies between the predicted and observed values are utilized to define a baseline distribution of prediction errors within a subject. This distribution is then used as a reference for calculating a summary “entropy” metric in follow-up segments of driving, such as when a driver may be distracted when using a cell phone. This same concept has also been applied to the lateral position of a vehicle (Dawson et al., 2006). The objective of this study was to ascertain whether entropy was affected by behavioral factors such as steering techniques and speed. We hoped to gain insight regarding the usefulness of entropy measures, and the appropriate interpretation of statistical tests based on entropy. METHODS We designed a simple driving route in a simulator known as SIREN (Rizzo, 2004), with a straight road segment of 3.7 km, followed by an S-curved road segment of 3.8 km. Using an expert driver familiar with the simulator, we performed a factorial experiment with different steering techniques (normal driving, swerving, and steering using a rigid grip and sudden “jerks”) and driving speeds (35 mph, 55 mph, and 75 mph). Data on steering wheel position and lane position were collected at 30 frames per second, and then reduced to 5-frame blocks of 167 msec each. Based on these blocks, we estimated the baseline parameter to characterize the prediction errors for each drive during the straight road section, and then applied this parameter to the straight and curved road sections in order to calculate entropy. This approach was used for both steering and lane position entropy. The data were analyzed using multiple linear regresssion to assess the affects of steering technique and speed, adjusting for road curvature. We also calculated Pearson correlation coefficients to measure the association between steering and lane position entropy. RESULTS Data were obtained on a total of 40 drive segments. Steering entropy ranged from 0.34 to 0.90, with a mean (SD) of 0.56 (0.16). Lane position entropy ranged from 0.34 to 0.93, with a mean (SD) of 0.61 (0.15). Compared to normal driving, steering behavior involving jerking motions tended to lower the steering entropy by 0.14 (p=0.012), and tended to lower the lane position entropy by 0.25 (p<0.001). Swerving in wide lateral motions had no effect on steering entropy, and only a minor effect on lane position entropy, decreasing it by 0.07. Compared to driving at 35 mph, driving at either 55 mph or 75 mph increased the steering entropy by an average of 0.08, but had no effect on lane position entropy. Although not our primary focus, we found that driving in curved sections tended to have higher entropy measures (increase of 0.21 for steering and 0.20 for lane position; p<0.001 in both cases). Despite a few outliers, the correlation between steering and lane position entropy was found to be high (r=0.84; see Figure 1). CONCLUSIONS Although entropy is often considered as an increasing function of workload, and would presumably increase in non-optimal conditions, some unsafe driving behaviors are actually negatively associated with entropy. Safe driving often involves making frequent minor steering adjustments, especially in curved sections of the road, which might lead to an increase in the entropy measure. If a driver rigidly holds onto the steering wheel and then makes large corrections when approaching or crossing a lane boundary, the fixed steering wheel position over several seconds may actually cause an apparent decrease in entropy. In summary, entropy may be a useful tool in quantifying vehicular control, but caution should be exercised when interpreting the results, as the associations involving entropy are not always in the anticipated direction
Evaluation of the AARP Driver Safety Program in Florida
Get PDFOBJECTIVES Older drivers are the fastest growing group of drivers on the road in the United States, both in terms of the number of drivers and annual mileage; also, per-mile-driven, this group has a crash rate nearly equivalent to that of younger drivers. One approach to reducing crash risk in this population has been educational programs aimed at improving driving skills and/or changing driving behaviors. This retrospective cohort study describes the impact of the AARP Driver Safety Program (DSP) in Florida on motor vehicle collisions and violations. METHODS Information on individuals who participated in the AARP DSP in the state of Florida in 2001 and 2002 was provided by the AARP. The Florida Department of Highway Safety and Motor Vehicles (FDHSMV) provided licensure information on all licensed drivers who were aged 60 and older as of January 1, 2001. With respect to violations and collisions, information dating from the mid-1990s to early 2005 was provided. A total of 232,192 unique records for DSP participants were available; however, of these, 38,321 records were excluded because they contained out-of-state, erroneous or missing driver’s license numbers and therefore could not be matched to the data provided by the FDHSMV. Of the remaining 193,871 records with legitimate Florida driver’s license numbers, a total of 140,282 (72.4%) could be linked to the data provided by the FDHSMV. Two separate analyses were conducted. The first analysis compared violation and collision rates for DSP participants before and after DSP participation. The second analysis compared violation and collision rates between DSP participants and DSP non-participants. RESULTS Overall, DSP participants experienced a 7% statistically significant decrease in collisions (rate ratio [RR] 0.93, 95% confidence interval [CI] 0.89-0.97); a similar decrease was observed for injury-related collisions (RR 0.92, 95% CI 0.88-0.98) but not for fatal collisions (RR 1.20, 95% CI 0.74-1.94). The decline in the overall collision rate can be attributed to a decline in not-at-fault collisions (RR 0.85, 95% CI 0.80-0.91); there was no change in at-fault collisions (RR 1.00, 95% CI 0.94-1.07). Following DSP participation, violation rates significantly decreased 15% (RR 0.85, 95% CI 0.83-0.87). This decrease was observed for all types of violations with the exception of failure to yield, improper turning and improper lane changing, all of which showed no change, and careless driving, which showed a statistically significant 11% increase (RR 1.11, 95% CI 1.03- 1.20). Prior to DSP participation, those who participated in the DSP had a significantly higher collision rate (RR 1.11, 95% CI 1.07-1.14) compared to DSP non-participants, independent of age, gender, and race. This significantly elevated rate was consistent across all types of collisions. Following DSP participation, the overall collision rate for DSP participants was higher than that of non-participants (RR 1.21, 95% CI 1.17-1.25), though there was no difference for injurious or fatal collisions. The RR for not-at-fault and at-fault collisions indicated a lower collision rate for participants compared to non-participants. With respect to violations, prior to DSP participation, those who ultimately took part in the DSP had a lower violation rate (RR 0.96, 95% CI 0.95-0.98), however, this was mostly attributable to seat belt usage (RR 0.64, 95% CI 0.61-0.68). For all other types of violations, DSP participants had higher rates than the rest of the population. After DSP participation, participants had a higher violation rate compared to non-participants (RR 1.09, 95% CI 1.08-1.11), as well as elevated rates for most types of violations. There was no difference for failure to obey traffic signals, careless/improper driving, or improper backing. DSP participants had a lower rate of seat belt violations. CONCLUSIONS The results of this analysis suggest that though individuals who participated in the DSP had an overall reduction in collision rates, this reduction was attributable to not-at-fault collisions. This likely indicates that DSP participants modified their driving habits following the program (e.g., reduced their exposure) and did not necessarily improve their driving skills. There was also a reduction is some types of collisions, as well as an increase in careless driving-related offenses. These reductions may reflect a greater adherence to traffic laws or may simply reflect a reduction in driving brought about by changes in driving habits. Compared to similarly aged Florida drivers who did not participate in the DSP, participants had higher collision rates prior to the DSP. After DSP participation, the observed differences between participants and non-participants were either diminished or inverted such that participants had lower rates compared to non-participants. Participants had an overall lower violation rate prior to the DSP but for the most common types of violations they had elevated rates. Following participation, DSP participants had a higher crash rate compared to the rest of the population. For specific types of violations the elevated rates persisted but were diminished in magnitude
Does Exposure to Distraction in an Experimental Setting Impact Driver Perception of Cell Phone Ease of Use and Safety?
Get PDFWe examined drivers’ perception of the ease and safety of cell phone use while driving before and after exposure to distraction in an experimental setting. During the study, each driver reflected on driving and task performance while engaged in conversation-like and arithmetic distraction tasks on a handsfree and hand-held cell phone. Hands-free phones were consistently rated easier to use and safer than hand-held cell phones by both age groups, despite equivalent decrements in driving performance. Younger drivers consistently rated cell phones to be easier to use and safer than did older drivers. After exposure to distraction, younger drivers’ perception of the ease of use declined relative to their initial ratings; however, there was no corresponding change in the ratings of safety. In contrast, older drivers’ perception of ease or safety did not change significantly post-exposure. A priori subjective ratings on various dimensions of driver skill and distraction were also examined with respect to age-related differences
Short and Predictive Assessment Battery of Fitness-to-Drive After Stroke
No full textThe objective of this study was to confirm the accuracy of a previously identified short assessment battery to predict fitness-to-drive after stroke in a new cohort of stroke survivors. This was a prospective study that included 43 (39 males and 4 females) participants who performed the pre-driving assessment that included a standardized on-road test at the Belgian Road Safety Institute in Brussels, Belgium. Participants were on average six months post stroke, not severely physically disabled, possessed valid drivers’ licenses and actively drove prior to stroke onset. Fitness-to-drive decisions made based on performance in 15 tests of a full scale assessment battery were predicted using only scores in three previously identified predictive tests. Performance in the three tests (figure of Rey, visual neglect (lateralized mean reaction time) and on-road test) was used to correctly predict 37 (86%) of the 43 participants’ driving fitness. The sensitivity and specificity of the predictions were 77% and 92% respectively. The outcome of this study shows that the short assessment battery is indeed a good predictor of fitness-to-drive in stroke survivors, especially those without severe deficits
Static and Dynamic Evaluation of the Driver Speed Perception and Selection Process
Get PDFSpeed impacts the extent to which mobility and safety are experienced across the surface transportation network. By expanding current understanding of speed perception and selection processes our ability to understand and comprehensively address speed-related issues will improve. Driving simulator technology has advanced the field of transportation research. However, it has been limited in its application to speed-related issues. Furthermore, static computer-based evaluations have been used as a means of establishing a preliminary understanding for driver interpretation of stimuli encountered in the roadway, but have been limited in their application to speed. These technologies allow for large sample populations to be evaluated quickly and safely. Phase I of this initiative examined driver ability to perceive travel speeds in a similar real world, simulated world, and static environment. The experimental course traversed roadway where land-use and posted speed limits varied. Drivers’ actual and perceived speeds were recorded at 20 identical “checkpoint” locations in each environment, and the results were analyzed across drivers and environments. Phase II examined three roadway attributes that impact the speed-selection process. A focus group was employed to build improved scenarios of interest for a full-scale static evaluation. In the static environment, 75 drivers were asked how fast they would travel while individual characteristics of the scenario displayed were modified. This multifaceted research initiative expands the potential application of advanced technology in speed-related research, and improves the understanding of factors that influence speed perception and selection processes
Using Utility Theory to Evaluate IVR Menu Structure and Reduce Driving Distraction
Get PDFIt has been shown that drivers often exhibit degraded driving performance while concurrently engaging in secondary tasks, such as talking on a mobile phone using navigation systems and other in-vehicle devices. As there seem to be limited solutions at present to hasten or limit these behaviors, this paper outlines how utility theory can be applied to design more efficient and understandable menus. To determine the value of information presented by an interface menu, the frequency of using information in the menu (goals) and the amount of effort it takes to accomplish these goals are quantified for each type of information. This paper outlines a utility analysis that compares the current Minnesota 511 traveler information system and an alternative design intended to improve the user experience and lighten the cognitive load of drivers. The analysis indicated that the proposed changes in design increase value to the user by helping them more efficiently find and identify requested information. Designers can use this technique in order to increase the value of menu information, and in turn help users find and identify requested information more efficiently. It is hoped that more efficient menus will reduce the amount of time and attention that drivers spend using them, allowing for increased attention on the primary task of driving
Conversations on an Embedded Phone While Driving: Predicted vs. Observed Real-World Airbag Deployment Crash Rates
Get PDFOBJECTIVE To evaluate hypotheses that may help explain the discrepancy between the predicted vs. observed real-world airbag-deployment crash rates during conversation on a mobile phone embedded in a vehicle. METHOD Previous epidemiological, laboratory, and closed-road studies predict a 2-8 times increase in relative risk of phone conversations during real-world driving compared to baseline driving. Counts of real-world crashes clearly associated with portable cell usage are difficult to obtain and incomplete. However a large and complete body of real-world data exists of conversation usage on mobile phones embedded in vehicles and crashes severe enough to deploy an airbag (Young, 2001). The degree of discrepancy between the observed numbers of real-world crashes in these studies and the predicted risks of wireless conversations from previous studies is calculated. Hypotheses are presented and evaluated that may help to explain the discrepancy. RESULTS The absolute frequency of airbag deployment crashes occurring during conversation on a wireless phone embedded in a vehicle is low, and the relative airbag deployment crash rate is no greater than baseline driving. The pros and cons of five hypotheses are evaluated to help explain the discrepancy from previous studies predicting an increased crash rate from wireless phone conversations in general: (1) the reaction time increase arising from conversations in previous studies may be too small to give rise to a detectable increase in real-world crash rates; (2) labbased event detection does not account fully for similar types of event detection in real driving, let alone for crashes (Angell et al., 2006; Curry et al., 2005; Young et al., 2005); (3) conversation may at times mitigate risks such as fatigue; (4) portable and embedded cell phones may have substantially different human factor properties; and (5) drivers may tend to change behavior during calls in ways that reduce net risk: place calls in relatively benign driving conditions, reduce risky driving maneuvers, increase headway, glance longer to the forward roadway, increase glances to mirrors after an event. CONCLUSIONS The observed real-world airbag-deployment crash rate during conversations on an embedded hands-free device is substantially lower than predicted by previous simulator, closed-road, or epidemiological studies. Several hypotheses, if validated, may help resolve the discrepancy. REFERENCES Angell, L.S., Auflick, L.L., Austria, P.A., Kochhar, D.S. & Tijerina, L. (2006). Driver workload metrics project: Task 2 final report. Submitted to U.S. Dept. of Transportation, FHA, & NHTSA under Cooperative Agreement Number DTFH61-01-X-00014. Curry, R.C., Greenberg, J.A., & Kiefer, R.J. (2005). NADS versus CAMP closed-course comparison examining ‘last second’ braking and steering maneuvers under various kinematic conditions. Crash Avoidance Metrics Partnership (CAMP), Contract DTFH61-01-X-00014, Washington, DC, August, DOT HS 809 925. Young, R. (2001). Association between embedded cellular phone calls and vehicle crashes involving air bag deployment. Proceedings of Driving Assessment 2001: International Symposium on Human Factors in Driver Assessment, Training and Vehicle Design, Snowmass, Utah, August, 390-400. Young, R.A., Aryal, B.J., Muresan, M., Ding, X., Oja, S. & Simpson, S. (2005). Road-to-lab: Validation of the Static Load Test for predicting on-road driving performance while using advanced in-vehicle information and communication devices. Proceedings of the Third International Driving Symposium on Human Factors in Driver Assessment, Training and Vehicle Design, Rockport, Maine, July, 240-25
Effects of Chinese Font Style and Color on Variable Message Signs
Get PDFVariable message signs (VMS) are important traffic control devices for increasing road utility and decreasing traffic accidents. This study investigated the effects of Chinese font style (Hei, Ming, and Kai) and font color (red, green, and yellow) of VMS on subjects’ response performance (response time and accuracy) from an ergonomic viewpoint. Computer-generated VMS stimuli were merged with driver’s-view driving video and projected onto a screen while subjects made responses. The results showed that Chinese font style and font color both were significant factors in subjects’ response performance. Subjects took less response time for Hei style than for Kai and Ming styles, and exhibited higher accuracy for Hei and Ming styles than for Kai style. Subjects responded faster and more correctly for yellow and green font colors than for red. Additionally, the interaction of font style and font color had a significant effect on subjects’ response performance. Response times for yellow and green colors were shorter than for red on each font style. Subjects had the longest time for Ming style in red color, while they had the least correct for Kai style in red color. The results from this study may assist in adopting appropriate Chinese font and color on VMS and in improving safe and efficient driving for motorists on the freeway