In my car the brake is on the right: pedal errors among older drivers

PURPOSE: To assess to what extent specific cognitive functions contribute to pedal errors among older drivers. METHODS: 180 subjects aged 65 and older completed a 30 min driving evaluation on a simulator as well as three cognitive tests, the Mini-Mental State Exam (MMSE), the Clock Drawing Test, and Trailmaking Part A and B. Analyses based on logistic regressions were performed using age, gender, MMSE, Trailmaking Part A and B, and Clock Drawing Test as independent variables. RESULTS: Results indicate that Clock Drawing is the best predictor of pedal errors (odds ratio=10.04, p<.0001, 95% CI: 3.80, 26.63) followed by age > or =84 (odds ratio 6.10, p<.05, 95% CI: 1.77, 21.03). In contrast, Trailmaking Part A and B, gender, and the MMSE were not significantly related to pedal errors. CONCLUSION: Executive dysfunction may be an important contributor to pedal errors and thus unsafe driving. Practitioners may wish to consider measures of executive function when evaluating patients for driving safety.     

Age-related declines in car following performance under simulated fog conditions

The present study examined age-related differences in car following performance when contrast of the driving scene was reduced by simulated fog. Older (mean age of 72.6) and younger (mean age of 21.1) drivers were presented with a car following scenario in a simulator in which a lead vehicle (LV) varied speed according to a sum of three sine wave functions. Drivers were shown an initial following distance of 18 m and were asked to maintain headway distance by controlling speed to match changes in LV speed. Five simulated fog conditions were examined ranging from a no fog condition (contrast of 0.55) to a high fog condition (contrast of 0.03). Average LV speed varied across trials (40, 60, or 80 km/h). The results indicated age-related declines in car following performance for both headway distance and RMS (root mean square) error in matching speed. The greatest decline occurred at moderate speeds under the highest fog density condition, with older drivers maintaining a headway distance that was 21% closer than younger drivers. At higher speeds older drivers maintained a greater headway distance than younger drivers. These results suggest that older drivers may be at greater risk for a collision under high fog density and moderate speeds.     

Applying the motorcyclist's perspective to improve car drivers' attitudes towards motorcyclists

This study sought to provide a first crucial step in the direction of developing an intervention program aimed at improving safe attitudes and skills among car drivers towards motorcycles. We intended to improve drivers’ attitudes towards motorcyclists by exposing them to demands that motorcyclists face on the road. Car drivers were exposed to hazard perception clips taken from a motorcyclist's perspective, and interactive hazards in a motorcycle simulator. Car hazard perception clips and a car simulator were used as control conditions. A questionnaire assessed participant knowledge and attitudes towards motorcyclists before and after the intervention. After the intervention participants had more empathic- and fewer negative-attitudes, as well as safer attitudes towards motorcyclists. Self-reported attitude-change suggested that the use of motorcycle hazard perception clips was more effective than the simulator, and the intervention was most effective for those car drivers who reported the most negative attitudes prior viewing the clips or riding the simulator. Providing car drivers with a perspective of the motorcyclist may prove to be a useful tool for promoting safer attitudes towards motorcyclists.     

Lower extremity injuries in automobile crashes2

The new United States National Crash Severity Study (NCSS) data on tow-away automobile crashes was reviewed to determine the details of the more severe injuries of the lower extremity. This review includes the frequency of injury by limb segments (pelvis, thigh, knee, leg and ankle/foot), the vehicle structure contacted to produce these injuries, and the injuries/contact differences among car occupants. Some of the finds are: of the various body regions having the more severe injuries, the lower extremity ranks second only to the thorax; lap-shoulder belted occupants hardly ever sustain the more severe lower extremity injuries; and severe lower extremity injuries occur primarily in frontal crashes. Extrapolation of the NCSS data for national estimates indicates that the more serious lower extremity injuries in car crash survivors approximately equals the total number of passenger car occupants who are killed annually (27,000).     

Driving simulator validation for speed research

The behavioral validation of an advanced driving simulator for its use in evaluating speeding countermeasures was performed for mean speed. Using mature drivers, 24 participants drove an instrumented car and 20 participants drove the simulator in two separate experiments. Participants drove on roads which contained transverse rumble strips at three sites, as well as three equivalent control sites. The three pairs of sites involved deceleration, and were the approaches to stop sign intersections, right curves, and left curves. Numerical correspondence (absolute validity), relative correspondence (or validity), and interactive (or dynamic) relative validity were analyzed, the latter using correlations developed from canonical correlation. Participants reacted to the rumble strips, in relation to their deceleration pattern on the control road, in very similar ways in both the instrumented car and simulator experiments, establishing the relative validities. However, participants generally drove faster in the instrumented car than the simulator, resulting in absolute validity not being established.     

The use of adaptation to reduce simulator sickness in driving assessment and research

The technical advancement of driving simulators has decreased their cost and increased both their accuracy and fidelity. This makes them a useful tool for examining driving behavior in risky or unique situations. With the approaching increase of older licensed drivers due to aging of the baby boomers, driving simulators will be important for conducting driving research and evaluations for older adults. With these simulator technologies, some people may experience significant effects of a unique form of motion sickness, known as simulator sickness. These effects may be more pronounced in older adults. The present study examined the feasibility of an intervention to attenuate symptoms of simulator sickness in drivers participating in a study of a driving evaluation protocol. Prior to beginning the experiment, the experimental groups did not differ in subjective simulator sickness scores as indicated by Revised Simulator Sickness Questionnaire scores (all p > 0.5). Participants who experienced a two-day delay between an initial acclimation to the driving simulator and the driving session experienced fewer simulator sickness symptoms as indicated by RSSQ total severity scores than participants who did not receive a two-day delay (F(1,88) = 4.54, p = .036, partial η² = .049). These findings have implications for improving client well-being and potentially increasing acceptance of driving simulation for driving evaluations and for driving safety research.     

Light truck vehicles (LTVs) contribution to rear-end collisions

Light truck vehicles (LTVs), comprising light-duty trucks, vans, and sport-utility vehicles (SUVs) drive higher and wider than passenger cars which could affect the visibility for the following passenger car driver. This paper investigates the contribution of LTVs to rear-end collisions resulting from horizontal visibility blockage using the University of Central Florida sophisticated reconfigurable driving simulator. Indeed, a sudden stop of a leading LTV, in the shadow of the blindness of the succeeding passenger car driver, may deprive the latter of a sufficient response time, which may lead to high probability of a rear-end collision. To investigate this issue, two scenarios were developed in the UCF driving simulator. The first scenario serves as a base scenario where the simulator car follows a passenger car, and the second scenario serves as a test scenario, where the simulator car follows an LTV. The results obtained by comparing the scenarios showed that LTVs produce more rear-end collisions at unsignalized intersections due to horizontal visibility blockage and due to the resulting drivers' behavior when driving behind an LTV.     

Concurrent processing of vehicle lane keeping and speech comprehension tasks

With the growing prevalence of using in-vehicle devices and mobile devices while driving, a major concern is their impact on driving performance and safety. However, the effects of cognitive load such as conversation on driving performance are still controversial and not well understood. In this study, an experiment was conducted to investigate the concurrent performance of vehicle lane keeping and speech comprehension tasks with improved experimental control of the confounding factors identified in previous studies. The results showed that the standard deviation of lane position (SDLP) was increased when the driving speed was faster (0.30 m at 36 km/h; 0.36 m at 72 km/h). The concurrent comprehension task had no significant effect on SDLP (0.34 m on average) or the standard deviation of steering wheel angle (SDSWA; 5.20° on average). The correct rate of the comprehension task was reduced in the dual-task condition (from 93.4% to 91.3%) compared with the comprehension single-task condition. Mental workload was significantly higher in the dual-task condition compared with the single-task conditions. Implications for driving safety were discussed.     

Correlation between eeg and driver's actions during prolonged driving under monotonous conditions

Prolonged driving under monotonous conditions decreases the vigilance of the human controller and his performance of the driving task. Variations of his control activity (vehicle related signals) were measured with the goal of receiving criteria for a warning device, which could improve the active safety of today's traffic. The investigations were performed on a rural circuit and on a driving simulator: the control variable for decreasing vigilance was the electro-encephalogram of the test subjects. Factor analysis and canonical correlation were used to investigate the relation between both data sets. The EEG parameters showed a frontal displacement under prolonged driving: thus a decreasing vigilance could be confirmed. Simultaneously the subjects' control activity in the tracking task became coarser. The accelerator pedal activity—which is a relatively free control variable—decreased with the test duration despite constant driving speed. This was explained with increased risk-acceptance at decreased performance or decreased vigilance.     

Emotional states of drivers and the impact on speed,acceleration and traffic violations—A simulator study

Maladjusted driving, such as aggressive driving and delayed reactions, is seen as one cause of traffic accidents. Such behavioural patterns could be influenced by strong emotions in the driver. The causes of emotions in traffic are divided into two distinct classes: personal factors and properties of the specific driving situation. In traffic situations, various appraisal factors are responsible for the nature and intensity of experienced emotions. These include whether another driver was accountable, whether goals were blocked and whether progress and safety were affected. In a simulator study, seventy-nine participants took part in four traffic situations which each elicited a different emotion. Each situation had critical elements (e.g. slow car, obstacle on the street) based on combinations of the appraisal factors. Driving parameters such as velocity, acceleration, and speeding, together with the experienced emotions, were recorded. Results indicate that anger leads to stronger acceleration and higher speeds even for 2 km beyond the emotion-eliciting event. Anxiety and contempt yielded similar but weaker effects, yet showed the same negative and dangerous driving pattern as anger. Fright correlated with stronger braking momentum and lower speeds directly after the critical event.     

Validating a driving simulator using surrogate safety measures

Traffic crash statistics and previous research have shown an increased risk of traffic crashes at signalized intersections. How to diagnose safety problems and develop effective countermeasures to reduce crash rate at intersections is a key task for traffic engineers and researchers. This study aims at investigating whether the driving simulator can be used as a valid tool to assess traffic safety at signalized intersections. In support of the research objective, this simulator validity study was conducted from two perspectives, a traffic parameter (speed) and a safety parameter (crash history). A signalized intersection with as many important features (including roadway geometries, traffic control devices, intersection surroundings, and buildings) was replicated into a high-fidelity driving simulator. A driving simulator experiment with eight scenarios at the intersection were conducted to determine if the subjects' speed behavior and traffic risk patterns in the driving simulator were similar to what were found at the real intersection. The experiment results showed that speed data observed from the field and in the simulator experiment both follow normal distributions and have equal means for each intersection approach, which validated the driving simulator in absolute terms. Furthermore, this study used an innovative approach of using surrogate safety measures from the simulator to contrast with the crash analysis for the field data. The simulator experiment results indicated that compared to the right-turn lane with the low rear-end crash history record (2 crashes), subjects showed a series of more risky behaviors at the right-turn lane with the high rear-end crash history record (16 crashes), including higher deceleration rate (1.80+/-1.20 m/s(2) versus 0.80+/-0.65 m/s(2)), higher non-stop right-turn rate on red (81.67% versus 57.63%), higher right-turn speed as stop line (18.38+/-8.90 km/h versus 14.68+/-6.04 km/h), shorter following distance (30.19+/-13.43 m versus 35.58+/-13.41 m), and higher rear-end probability (9/59=0.153 versus 2/60=0.033). Therefore, the relative validity of driving simulator was well established for the traffic safety studies at signalized intersections.     

Older drivers’ opinions of criteria that inform the cars they buy: A focus group study

Safe driving in older adulthood depends not only on health and driving ability, but also on the driving environment itself, including the type of vehicle. However, little is known about how safety figures into the older driver's vehicle selection criteria and how it ranks among other criteria, such as price and comfort. For this purpose, six focus groups of older male and female drivers (n = 33) aged 70–87 were conducted in two Canadian cities to explore vehicle purchasing decisions and the contribution of safety in this decision. Themes emerged from the data in these categories: vehicle features that keep them feeling safe, advanced vehicular technologies, factors that influence their car buying decisions, and resources that inform this decision. Results indicate older drivers have gaps with respect to their knowledge of safety features and do not prioritize safety at the time of vehicle purchase. To maximize the awareness and uptake of safety innovations, older consumers would benefit from a vehicle design rating system that highlights safety as well as other features to help ensure that the vehicle purchased fits their lifestyle and needs.     

Effects of valerian on subjective sedation,field sobriety testing and driving simulator performance

IntroductionThe availability of herbal medicines over-the-counter (OTC) has increased the use of natural products for self-treatment. Valerian has been used to effectively treat generalized anxiety disorder and insomnia. Studies suggest that valerenic acid may increase gamma-aminobutyric acid (GABA) modulation in the brain. Benzodiazepines have a similar mechanism of action and have been linked to an increased risk of hospitalizations due to traffic accidents. Despite the risk of somnolence, the safety of driving while under the influence of valerian remains unknown.PurposeThe purpose of the study was to determine the effects of a one-time valerian 1600 mg dose on subjective sedation effects, standardized field sobriety testing (SFST) and driving simulator performance parameters.MethodsThe study design was a randomized, placebo-controlled, double-blind, cross-over trial. For each session, participants received either a dose of valerian or placebo. The outcome measures included a simple visual reaction test (SVRT), subjective sleepiness scales, SFST performance scores, and driving simulator performance parameters.ResultsThere were no significant differences in the SVRT or sleepiness scales between placebo and valerian exposures, but the study may have been underpowered. SFST total and individual test failure rates were not significantly different between the two exposures. The driving simulator performance parameters were equivalent between the two exposure conditions.ConclusionsA one-time valerian 1600 mg dose, often used to treat insomnia, does not appear to impair driving simulator performance after acute ingestion.     

Determination of pre-impact occupant postures and analysis of consequences on injury outcome. Part I: a driving simulator study

This paper considers pre-impact vehicle maneuvers and analyzes the resulting driver motion from their comfort seating position. Part I of this work consists of analyzing the driver behavior during a crash. The study is conducted using the LAMIH driving simulator and involves 76 participants. The emergency situation is created by a truck emerging from behind a tractor on the opposite side of the road and tearing along the participant. The driver positioning throughout the simulation is recorded via five video cameras allowing view of the front scene, the driver face, feet and pedals, hands on the steering wheel and global lateral view. Data related to braking force, seat pressure, muscular activity for major groups of muscles and actions on the steering wheel are also collected.The typical response to this type of emergency event is to brace rearward into the seat and to straighten the arms against the steering wheel, or, to swerve to attempt to avoid the impacting vehicle. While turning the steering wheel, the forearm can be directly positioned on the airbag module at time of crash which represents a potential injurious situation.These positions are used in Part II to determine scenario of positions for numerical simulation of a frontal collision.     

The effects of texting on driving performance in a driving simulator: The influence of driver age

Distracted driving is a significant contributor to motor vehicle accidents and fatalities, and texting is a particularly significant form of driver distraction that continues to be on the rise. The present study examined the influence of driver age (18–59 years old) and other factors on the disruptive effects of texting on simulated driving behavior. While ‘driving’ the simulator, subjects were engaged in a series of brief text conversations with a member of the research team. The primary dependent variable was the occurrence of Lane Excursions (defined as any time the center of the vehicle moved outside the directed driving lane, e.g., into the lane for oncoming traffic or onto the shoulder of the road), measured as (1) the percent of subjects that exhibited Lane Excursions, (2) the number of Lane Excursions occurring and (3) the percent of the texting time in Lane Excursions. Multiple Regression analyses were used to assess the influence of several factors on driving performance while texting, including text task duration, texting skill level (subject-reported), texting history (#texts/week), driver gender and driver age. Lane Excursions were not observed in the absence of texting, but 66% of subjects overall exhibited Lane Excursions while texting. Multiple Regression analysis for all subjects (N = 50) revealed that text task duration was significantly correlated with the number of Lane Excursions, and texting skill level and driver age were significantly correlated with the percent of subjects exhibiting Lane Excursions. Driver gender was not significantly correlated with Lane Excursions during texting. Multiple Regression analysis of only highly skilled texters (N = 27) revealed that driver age was significantly correlated with the number of Lane Excursions, the percent of subjects exhibiting Lane Excursions and the percent of texting time in Lane Excursions. In contrast, Multiple Regression analysis of those drivers who self-identified as not highly skilled texters (N = 23) revealed that text task duration was significantly correlated with the number of Lane Excursions. The present studies confirm past reports that texting impairs driving simulator performance. Moreover, the present study demonstrates that for highly skilled texters, the effects of texting on driving are actually worse for older drivers. Given the increasing frequency of texting while driving within virtually all age groups, these data suggest that ‘no texting while driving’ education and public service messages need to be continued, and they should be expanded to target older drivers as well.     

Age differences in simulated driving performance: Compensatory processes

In the context of driving, the reported experiment examines compensatory processes for age-related declines in cognitive ability. Younger (26–40 years) and older (60+ years) participants (n = 22 each group) performed a car following task in a driving simulator. Several performance measures were recorded, including assessments of anticipation of unfolding traffic events. Participants also completed a range of measures of cognitive ability – including both fluid and crystallised abilities. Three examples of age-related compensation are reported: (i) older drivers adopted longer headways than younger drivers. Data were consistent with this being compensation for an age-related deficit in complex reaction time; (ii) older drivers with relatively higher cognitive ability anticipated traffic events more frequently, whereas the reverse pattern was found for younger drivers; and, (iii) older drivers with greater crystallised ability were less reliant on spatial ability to maintain lane position. Consistent with theories of ‘cognitive reserve’, interactions between crystallised ability and age for self-report workload suggested that compensation for age-related cognitive ability deficits required investment of additional effort. Results are considered in the context of the prospects of further assessment of older drivers.     

Effect of shoulder width, guardrail and roadway geometry on driver perception and behavior

Roadway design is one of the most significant factors that affect driving behavior and perceived safety. The current study tests the combined effects of three roadway design elements – shoulders width, guardrail existence and roadway geometry (curvature) – on objective driving measures (speed and lane position), and subjective measures (perceived safe driving speed and estimated road safety).Twenty two drivers participated in an experiment with a driving simulation. In the first part objective driving data were collected, and in the second part subjective paper–pencil evaluations were requested of the perceived safety of 30 different scenarios that were previously experienced in the simulator. The scenarios consisted of the various combinations of the three roadway design elements.The results showed a significant effect of roadway geometry on both objective and subjective measures. The shoulders width had a significant effect on actual speed, on lane position, and on perceived safe driving speed, but only when a guardrail was present.These findings illustrate the perceptual role of a guardrail in defining the perceived safety margins that various shoulder widths provide. When a guardrail is absent, the width of the shoulder loses much of its benefits and effects on driving behavior. The results also demonstrate that roadway geometry can be used to reduce driving speeds, but at the same time it can have a negative effect on maintaining a stable lane position in sharp curves. Thus, controlling the width of road shoulders and the placement of guardrails seems to be a safer approach to speed and lane position control.     

An empirical study of the effectiveness of electronic stability control system in reducing loss of vehicle control

A significant percentage of fatal vehicle crashes involve loss of control (LOC). Electronic stability control (ESC) is an active safety system that detects impending LOC and activates counter-measures that help the driver maintain or re-gain control. To assess the effectiveness of ESC in preventing LOC, an empirical study was conducted on a high-fidelity driving simulator. The ESC systems for two vehicles were incorporated into the simulator's dynamics code which was calibrated to ensure engineering validation. The study utilized three scenarios designed to recreate typical LOC situations, and was designed to assess the effects of ESC presence, vehicle type, scenario, age and gender. A total of 120 research participants completed the study. Results showed a statistically significant reduction in LOC with ESC compared to without ESC (F = 52.72, p < 0.0001). The study findings of 5% LOC with ESC and 30% without ESC match several epidemiological studies that have analyzed ESC effectiveness on real-world crashes, providing strong support to the use of driving simulation for studying driver behavior. Study conclusions suggest that wide-spread utilization of ESC is likely to reduce traffic fatalities.     

Impact of distracted driving on safety and traffic flow

Studies have documented a link between distracted driving and diminished safety; however, an association between distracted driving and traffic congestion has not been investigated in depth. The present study examined the behavior of teens and young adults operating a driving simulator while engaged in various distractions (i.e., cell phone, texting, and undistracted) and driving conditions (i.e., free flow, stable flow, and oversaturation). Seventy five participants 16–25 years of age (split into 2 groups: novice drivers and young adults) drove a STISIM simulator three times, each time with one of three randomly presented distractions. Each drive was designed to represent daytime scenery on a 4 lane divided roadway and included three equal roadway portions representing Levels of Service (LOS) A, C, and E as defined in the 2000 Highway Capacity Manual. Participants also completed questionnaires documenting demographics and driving history. Both safety and traffic flow related driving outcomes were considered. A Repeated Measures Multivariate Analysis of Variance was employed to analyze continuous outcome variables and a Generalized Estimate Equation (GEE) Poisson model was used to analyze count variables. Results revealed that, in general more lane deviations and crashes occurred during texting. Distraction (in most cases, text messaging) had a significantly negative impact on traffic flow, such that participants exhibited greater fluctuation in speed, changed lanes significantly fewer times, and took longer to complete the scenario. In turn, more simulated vehicles passed the participant drivers while they were texting or talking on a cell phone than while undistracted. The results indicate that distracted driving, particularly texting, may lead to reduced safety and traffic flow, thus having a negative impact on traffic operations. No significant differences were detected between age groups, suggesting that all drivers, regardless of age, may drive in a manner that impacts safety and traffic flow negatively when distracted.     

Microstructural and electrical changes in nickel manganite powder induced by mechanical activation

Nickel manganite powder synthesized by calcination of a stoichiometric mixture of manganese and nickel oxide was additionally mechanically activated in a high energy planetary ball mill for 5-60 min in order to obtain a pure NiMn₂O₄ phase. The as-prepared powders were uniaxially pressed into disc shape pellets and then sintered for 60 min at 1200 °C. Changes in the particle morphology induced by mechanical activation were monitored using scanning electron microscopy, while changes in powder structural characteristics were followed using X-ray powder diffraction. The ac impedance spectroscopy was performed on sintered nickel manganite samples at 25 °C, 50 °C and 80 °C. It was shown that mechanical activation intensifies transport processes causing a decrease in the average crystallites size, while longer activation times can lead to the formation of aggregates, defects and increase of lattice microstrains. The observed changes in microstructures were correlated with measured electrical properties in order to define optimal processing conditions.