Crash causation, countermeasures, and policy - Editorial.

This editorial is both an introduction to the papers that make up this special issue (on the Relationship between Crash Causation, Countermeasures, and Policy) and an attempt at drawing conclusions. To assist the reader, we begin with a brief description of the subject matter of each paper. As expected, the authors tackle different aspects of this general topic and often differ in their conclusions. We follow up by asking: Are in-depth crash causation studies helpful? Can the need for understanding causation be defended? Does the Swiss Cheese Metaphor require revision? What are the building blocks on which the crash injury prevention programs rest? Can one really avoid comparing costs and benefits? These are some of the issues we raise and discuss. We end by offering for consideration a realistic model to link causes, countermeasures, policy, and responsibility for public safety.

Crash causes, countermeasures, and safety policy implications.

There are interrelationships between crash causes, countermeasures, and policy implications, but they are not necessarily direct and obvious. Part of the problem is the definition of a cause. The seminal 1979 Indiana University "Study of Accident Causes" has cemented some false assumptions that must be overcome to yield an effective crash countermeasures policy. The taxonomy of crash causes and the prevalence of different causes are determined by the investigators, who are biased in different ways. The prevalent notion that approximately 90 percent of the crashes are due to human errors or failures is due to a threshold bias, and the implied notion that 90 percent of the countermeasures should be directed at changing these behaviors is based on an erroneous assumption that the cure must be directly linked to the stated cause. A more balanced approach to the definition of a cause and to the search for crash countermeasures is needed, and the safe system approach appears to be a most promising one.

Expert evaluation of traffic signs: conventional vs. alternative designs.

Traffic sign comprehension is significantly affected by their compliance with ergonomics design principles. Despite the UN Convention, designs vary among countries. The goal of this study was to establish theoretical and methodological bases for evaluating the design of conventional and alternative signs. Thirty-one conventional signs and 1-3 alternatives for each conventional sign were evaluated for their compliance with three ergonomics guidelines for sign design: physical and conceptual compatibility, familiarity and standardisation. Twenty-seven human factors and ergonomics experts from 10 countries evaluated the signs relative to their compliance with the guidelines. Analysis of variance across alternatives revealed that for 19 of the 31 signs, an alternative design received a significantly higher rating in its ergonomics design than the conventional sign with the same meaning. We also found a very high correlation between the experts' ratings and comprehension from previous studies. In conclusion, many countries use signs for which better alternative designs exist, and therefore UN Convention signs should be re-examined, and ergonomics experts evaluation can serve as a good surrogate for road users' comprehension surveys. Practitioner summary: This study presents theoretical and methodological bases for evaluating the design of UN Conventional and alternative traffic signs. Human factors and ergonomics experts evaluated 31 conventional and 68 alternative road signs, based on ergonomics principles for sign design. Results indicated the need to re-examine poorly designed UN Convention signs.

Cognitive Workload ≠ Crash Risk: Rejoinder to Study by Strayer et al. (2015).

Strayer et al.'s article is a significant attempt to scale the cognitive workload of different potentially distracting tasks. It is tempting but not warranted to equate the workload with the relative risk of crash involvement. In this article, I list the reasons why the scaling should not be generalized to safety implications in real driving and argue for the combination of studies of maximal performance assessment (e.g., simulation) with behavioral assessment (e.g., naturalistic driving).

Evaluating the efficiency of local municipalities in providing traffic safety using the Data Envelopment Analysis.

The purpose of this study was to estimate the relative efficiency of 197 local municipalities in traffic safety in Israel during 2004-2009, using Data Envelopment Analysis (DEA). DEA efficiency is based on multiple inputs and multiple outputs, when their weights are unknown. We used here inputs reflecting the resources allocated to the local municipalities (such as funding), outputs include measures that reflect reductions in accidents (such as accidents per population), and intermediate variables known as safety performance indicators (SPI): measures that are theoretically linked to crash and injury reductions (such as use of safety belts). Some of the outputs are undesirable. Using DEA, the local municipalities were rank-scaled from the most efficient to the least efficient and required improvements for inefficient municipalities were calculated. We found that most of the improvements were required in two intermediate variables related to citations for traffic violations. Several DEA versions were used including a two-stage model where in the first stage the intermediate variables are the outputs, and in the second stage they are the inputs. Further analyses utilizing multiple regressions were performed to verify the effect of various demographic parameters on the efficiency of the municipalities. The demographic parameters tested for each local municipality were related to the size, age, and socio-economic level of the population. The most significant environmental variable affecting the efficiency of local municipalities in preventing road accidents is the population size of the local authority; the size has a negative effect on the efficiency. As far as we could determine, this is the first time that the DEA is used to measure the efficiency of local municipalities in improving traffic safety.

Enhancement of road delineation can reduce safety.

BACKGROUND: New in-vehicle technologies often outpace the scientific support for their value. In lieu of valid and consistent scientific support, common wisdom is used, as in the assumption that enhanced roadway delineation improves driving safety. OBJECTIVE: To evaluate the effects of a Visibility Enhancement System that selectively improves lane markers' visibility on driving safety. METHOD: A simulation experiment assessed the effects of an in-car lane Visibility Enhancement System (VES) that highlights the edges of the road ahead on driver's behavior and overall safety, under normal and reduced visibility conditions. Thirty drivers drove in a fix-based simulator through a winding rural road, while attempting to avoid un-enhanced and unexpected obstacles that appeared on the driving lane from time to time. The simulated VES highlighted the road edges up to a distance of 90 m with two alternative configurations: two continuous red lines or a series of red crosses. The effects of the two VES configurations on performance were measured during night and fog driving. Performance measures included speed, lane keeping behavior, eye scanning pattern, reaction time (RT) and collisions with the un-enhanced unexpected obstacles. Subjective measures included confidence and stress. RESULTS: With the VES, drivers were more confident, less stressed, and drove faster, but had almost twice as many collisions with the unexpected obstacles. Also, steering/braking RT to the obstacles was longer with the VES than without it by nearly 44 msec. CONCLUSIONS: The results are consistent with Lebowitz's theory (1977). While the VES enhanced spatial orientation, it fooled the drivers into assuming that the visibility of obstacles on the road was also improved, and thus actually reduced safety. PRACTICAL APPLICATIONS: When visibility is an issue in nighttime crashes, the site-specific crashes should be investigated, in cases of collision with objects-on-the-road, improved delineation should be ruled out.

Radiology department, human factors and organizational perspectives: using action research to improve patient safety.

BACKGROUND: Action research is a participatory research method based on active cooperation between researchers and subjects. In clinical practice, action research enables active involvement of workers in developing and implementing actions promoting patient safety. This article describes a participatory action research project that was conducted in the radiology department of a tertiary care university hospital. The main objectives were: identifying potential adverse events in the department of radiology, and offering a proactive approach to improving patient safety. METHODS: Phase one of the study included observing 100 patients in three units of the department and identifying potential adverse events using an observation form. According to the data obtained from the observations, multidisciplinary research teams developed and initiated, together with front-line workers, four types of interventions: ergonomic interventions in work environment design, interventions in work procedure and task design, training and guidance, and managerial interventions. Phase two included evaluation of the interventions after six months of implementation. RESULTS: Results showed different weaknesses in each of the three radiology units tested, including incomplete medical information necessary for performing the radiological procedure, and discontinuity of care. Post-intervention observations showed a significant reduction in the prevalence of potential adverse events. At the Angiography unit, potential adverse events related to incomplete medical information dropped from 50% to 32%, and at the CT unit they dropped from 70% to 23%. At the MRI unit potential adverse events related to discontinuity of care dropped from 61% to 19%. CONCLUSIONS: The current study demonstrates the value of action research in non-hospitalizing health units and the benefits of cooperation between medical teams and human factor professionals in promoting patient safety. Methods similar to those described in the current paper are applicable to medical work teams in a broad range of practices.

To call or not to call--that is the question (while driving).

We studied whether decisions to engage in cell phone conversation while driving and the consequences of such decisions are related to the driver's age, to the road conditions (demands of the driving task), and to the driver's role in initiating the phone call (i.e. the driver as caller vs. as receiver). Two experiments were performed in a driving simulator in which driver age, road conditions and phone conversation, as a secondary task, were manipulated. Engagement in cell phone conversations, performance in the driving and the conversation tasks, and subjective effort assessment were recorded. In general, drivers were more willing to accept incoming calls than to initiate calls. In addition, older and younger drivers were more susceptible to the deleterious effects of phone conversations while driving than middle aged/experienced drivers. While older drivers were aware of this susceptibility by showing sensitivity to road conditions before deciding whether to engage in a call or not, young drivers showed no such sensitivity. The results can guide the development of young driver training programs and point at the need to develop context-aware management systems of in-vehicle cell phone conversations.

Increasing motorcycles attention and search conspicuity by using Alternating-Blinking Lights System (ABLS).

Poor conspicuity of Powered Two-Wheelers (PTW) is one of the main factors contributing to their involvement in accidents. The current study examined the influence of different rider's outfits on PTWs' detectability, and evaluated the potential of a unique Alternating-Blinking Lights System (ABLS) to increase the rider's conspicuity. This study included two experiments that examined the visual search involved in the process of scanning video clips of dynamic traffic scenes. The first experiment examined PTWs' attention conspicuity, while the second evaluated PTWs' search conspicuity. In the attention conspicuity experiment participants were not alerted to the possible presence of a PTW and were asked to report the types of vehicles that were present in each video clip. In the search conspicuity experiment the participants were asked to actively search for a PTW and report its presence or absence in each video clip. Every participant was presented with a series of 96 video clips, 48 with a PTW and 48 without (controls). The independent variables were: (i) level of ambient illumination, (ii) road type, (iii) PTW's initial distance from the viewer, and (iv) rider's outfit. The results of the attention conspicuity experiment indicated that the environmental context has a strong effect on the probability of detecting the PTW. The ABLS increased the PTWs' attention conspicuity by moderating the effects of environmental context, and was most effective at dusk and in urban environments. The results of the search experiment indicated that detection rates decreased and reaction time (RT) increased as the level of luminance decreased. RT was shortest with the ABLS across all driving environments. The ABLS increased PTWs detection rates in both experiments and mitigated the difference in detection rates between the attention and search conspicuity experiments. The results indicated that the ABLS was the most potent conspicuity treatment of the ones evaluated in this study. In conclusion, PTW conspicuity should be enhanced by incorporating aspects of both attention and search conspicuity. The riders need to take into consideration the perceptual characteristics of their riding environment, and be equipped with a conspicuity aid that is less susceptible to the changing environment and provides the rider with a unique visual signature. In parallel, the expectancy of car drivers to the presence of PTWs should be increased.

Safety and mobility of vulnerable road users: pedestrians, bicyclists, and motorcyclists.

Traffic safety has improved greatly over the past few decades, but the progress in the safe mobility of vulnerable road users (VRUs) - especially motorcycle riders - has not been as consistent. The changing trends towards healthier and eco-friendlier lifestyle, coupled with the rising costs of fuel have increased the exposure and injury risk of pedestrians, motorcyclists, and bicyclists, especially in urban areas. To address the safe mobility issues of VRUs, Israel's National Road Safety Authority organized an international conference on the topic. This special issue contains the papers of the three plenary talks related to the safe mobility of each of the VRUs, and 18 more papers of the over 100 papers presented at the conference that were accepted for publication in AAP following the Journal's review process.

Pedestrians' behaviour in cross walks: the effects of fear of falling and age.

Pedestrians are exposed to risks when crossing roads in urban areas. The crossing behaviour of pedestrians was studied as a factor contributing to their exposure to risks on the road and to their involvement in road accidents. This work explores two specific aspects of crossing behaviour: crossing speed and head pitches-the proportion of time pedestrians point their heads down (rather than towards the traffic) when crossing a road. The last one is used as an indicator of the (lack of) attention to cross-traffic. We also explored the possible effect of fear of falling (FOF) among pedestrians, as it might be associated with slow walking, less attention to cross traffic, and more attention to the pavement and their footsteps. This paper reports on a field study that combined an observatory technique with short survey. 203 pedestrians in two sites (signalised and unsignalised crosswalks) were video recorded while crossing the road. The FOF of pedestrians and other measures of pedestrian behaviour at crosswalks were revealed by means of questionnaire. Age and gender had the most significant effects on crossing speed, and FOF had a significant effect on the proportion of downward head pitches during crossing.

Attention and search conspicuity of motorcycles as a function of their visual context.

BACKGROUND: Over the years, PTWs' number of accidents have increased dramatically and have accounted for a high percentage of the total traffic fatalities. The majority of those accidents occur in daylight, clear weather, and at light to moderate traffic conditions. The current study included two experiments. The first experiment evaluated the influence of PTW attention conspicuity on the ability of un-alerted viewers to detect it, whereas the second experiment evaluated the PTWs search conspicuity to alerted viewers. The independent variables in both experiments included driving scenarios (urban and inter-urban), PTW rider's outfit (black, white, and reflective) and PTW distance from the viewer. METHOD: 66 students participated in experiment 1. Every participant was presented with a series of pictures and was asked to report all the vehicle types present in each picture. Experiment 2 included 64 participants and incorporated the same pictures as experiment 1. However, in this experiment the participants were instructed to search the pictures for a PTW and to report its presence or absence as soon as they reach a decision. RESULTS: In experiment 1 the detection of a PTW depended on the interaction between its distance from the viewer, the driving scenario and PTW rider's outfit. For an un-alerted viewer when the PTW was distant the different outfit conditions affected its' attention conspicuity. In urban roads, where the background surrounding the PTW was more complex and multi-colored, the reflective and white outfits increased its attention conspicuity compared to the black outfit condition. In contrast, in inter-urban roads, where the background was solely a bright sky, the black outfit provided an advantage for the PTW detectability. In experiment 2, the average PTW detection rate of the alerted viewers was very high and the average reaction time to identify the presence of a PTW was the shortest in the inter-urban environment. Similar to the results of experiment 1, in urban environments the reflective and white clothing provided an advantage to the detection of the PTW, while in the inter-urban environment the black outfit presented an advantage. Comparing the results of the two experiments revealed that at the farthest distance, the increased awareness in the search conspicuity detection rates were three times higher than in the attention conspicuity. CONCLUSIONS: The conspicuity of a PTW can be increased by using an appropriate rider's outfit that distinguishes him/her from the background scenery. Thus, PTW riders can actively increase their conspicuity by taking into account the driving route (crowded urban/inter urban), eventually increasing the probability of being detected by the other road users. In addition, increasing the alertness and expectancy of drivers to the presence of PTWs can increase their search conspicuity.

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 analysis of alcohol breath tests results with portable and desktop breath testers as surrogates of blood alcohol levels.

There is a perceived tradeoff between the ease of measuring alcohol in the body and the accuracy of the result. Direct tests of blood alcohol concentrations are considered the most accurate, desktop stationary breath testers based on electro-chemical infra-red technology are slightly less accurate, but accepted for evidentiary purposes in most jurisdictions, and quick portable breath testers based on fuel-cell technology are the easiest to administer but not acceptable in many courts. This study compared the accuracy of an evidentiary portable breath tester and an evidentiary desktop breath tester relative to blood alcohol concentrations. Inverse regressions were used to obtain confidence limits for the alcohol levels as read by the breath testers that would provide tradeoffs of false positives and false negatives for three levels of confidence: 95%, 96%, and 98%; corresponding to false positive values of 2.5%, 2%, and 1%, respectively. A decision tree model is offered for the optimal use of the three measures, so that portable breath testers can be sufficient for high level BrAC, stationary breath testers can be sufficient for medium level BrAC, and blood tests are recommended for still lower BrACs. The model provides quantitative BrAC threshold levels for the two most common BAC levels used to imply DWI: 50mg/dl and 80 mg/dl.

Usage and perceived effectiveness of fatigue countermeasures for professional and nonprofessional drivers.

BACKGROUND: Drivers adopt various strategies in order to cope with fatigue and falling asleep at the wheel. These strategies include a wide range of activities that may invigorate the body and/or the mind. OBJECTIVES: To compare usage patterns and to evaluate the perceived effectiveness of different coping behaviors adopted by professional and nonprofessional drivers in order to maintain alertness. METHOD: The study was conducted using a large-scale survey, filled by 100 professional and 90 nonprofessional drivers. RESULTS: Listening to the radio and opening the window were the most frequently used and also perceived as highly effective coping behaviors by both groups of drivers. Talking on a cellular phone or with a passenger were more frequently used by nonprofessional drivers whereas, planning rest stops ahead, stopping for a short nap and drinking coffee were more frequently used by professional drivers. These methods were also perceived as more effective by professional than by the nonprofessional drivers and their usage frequency highly correlated with their perceived effectiveness. CONCLUSIONS: Nonprofessional drivers counteract fatigue only at the tactical/maneuvering level of the drive. Hence, they tend to adopt methods that help them pass the time and reduce their feeling of boredom but do not require advance preparations or adjustments in the driving. In contrast, professional drivers counteract fatigue also at the strategic/planning level of driving, and use a much larger repertoire of coping-behaviors. IMPLICATIONS: Fatigue countermeasures should include all levels of the driving task hierarchy, and experience-based countermeasures used by professional drivers should be considered for experimental validation.

The effect of alcohol, THC and their combination on perceived effects, willingness to drive and performance of driving and non-driving tasks.

BACKGROUND: Driving under the influence of drugs (DUID) is one of the main causes of car accidents. Alcohol and marijuana are the most popular drugs among recreational users. Many classify these drugs as "Light" drugs and therefore allow themselves to drive after consuming them. OBJECTIVE: The study had two main objectives: 1) to investigate the effect of alcohol (BAC=0.05%), THC (13 mg) and their combination on driving and non-driving tasks. 2) to investigate the extent to which people are willing to drive based on their subjective sensations and their perceived effects of the drugs. METHOD: 7 healthy men and 5 healthy women, ages 24-29, all recreational users of alcohol and marijuana, completed 5 experimental sessions. Sessions included: drinking and smoking placebo, drinking alcohol and smoking placebo, drinking placebo and smoking THC, drinking alcohol and smoking THC, drinking placebo and smoking placebo 24 hours after drinking alcohol and smoking THC. Three types of measures were used: subjective perceptions (with questionnaires), performance parameters of the driving and non-driving tasks (arithmetic task and a secondary target detection task) and physiological changes (heart rate). RESULTS: Overall, the combination of alcohol and THC had the most intense effect after intake. This effect was reflected in performance impairments observed in the driving and non-driving tasks, in the subjective sensations after intake, and in the physiological measures. Despite significant differences in the size of the effects after the various treatments, there were no differences in the distances subjects were willing to drive while under the influence on each of the treatments.

Age, skill, and hazard perception in driving.

This study examined the effects of age and driving experience on the ability to detect hazards while driving; namely, hazard perception. Studies have shown that young-inexperienced drivers are more likely than experienced drivers to suffer from hazard perception deficiencies. However, it remains to be determined if this skill deteriorates with advancing age. Twenty-one young-inexperienced, 19 experienced, and 16 elderly drivers viewed six hazard perception movies while connected to an eye tracking system and were requested to identify hazardous situations. Four movies embedded planned, highly hazardous, situations and the rest were used as control. Generally, experienced and older-experienced drivers were equally proficient at hazard detection and detected potentially hazardous events (e.g., approaching an intersection, pedestrians on curb) continuously whereas young-inexperienced drivers stopped reporting on hazards that followed planned, highly hazardous situations. Moreover, while approaching T intersections older and experienced drivers fixated more towards the merging road on the right while young-inexperienced drivers fixated straight ahead, paying less attention to potential vehicles on the merging road. The study suggests that driving experience improves drivers' awareness of potential hazards and guides drivers' eye movements to locations that might embed potential risks. Furthermore, advanced age hardly affects older drivers' ability to perceive hazards, and older drivers are at least partially aware of their age-related limitations.

Evaluation of experience-based fatigue countermeasures.

BACKGROUND AND OBJECTIVE: Strategies adopted by drivers in order to cope with fatigue and falling asleep at the wheel include a variety of activities that may invigorate the body and/or the mind. The objectives of the current study were to examine the effectiveness of an energy drink and a non-traditional manual-dexterity/mastication activity as fatigue countermeasures. METHOD: Twenty subjects participated in this driving simulator study. Each driving session lasted 2h and each driver drove under three conditions: after consumption of an energy drink, while engaged in a self-paced manual-dexterity/mastication secondary task (shelling and eating sunflower seeds), and in a control condition with neither. Fatigue effects were assessed on three dimensions: subjective evaluations (using the Swedish Occupational Fatigue Inventory), a physiological indicator (heart rate variability), and driving performance measures (speed, steering, and lane deviations). RESULTS: The subjective and physiological measures showed a significant effect of both treatments in counteracting the effects of fatigue when compared to the control condition. The results of the driving performance measures indicated that the energy drink was effective in counteracting fatigue, while the secondary task was as effective as the energy drink in counteracting fatigue on measures that did not rely on hand movements. CONCLUSIONS: Drinking an energy drink prior to the driving task has a significant, positive effect in counteracting fatigue, though it may have long-term negative rebound effects. The manual-dexterity/mastication secondary task can temporarily counteract the subjective and physiological effects of fatigue while driving, but can interfere with vehicle handling.

Looks are (almost) everything: where drivers look to get information.

OBJECTIVE: To describe the impact of Rockwell's early eye movements research. BACKGROUND: The advent of a new technology enabling measurements of eye movements in natural environments launched the seminal research of a Human Factors pioneer, Tom Rockwell, into how drivers process visual information. METHOD: In two seminal Human Factors articles -"Mapping Eye-Movement Pattern to the Visual Scene in Driving: An Exploratory Study" (Mourant & Rockwell, 1970) and "Strategies of Visual Search by Novice and Experienced Drivers" (Mourant & Rockwell, 1972)- Rockwell and his student, Ron Mourant, examined drivers' eye movements in naturalistic driving environments. RESULTS: The analyses of the visual fixations revealed systematic relationships between the sources of information the drivers needed to drive safely and the spatial distributions of their visual fixations. In addition, they showed that as drivers gain skill and experience, their pattern of fixations changes in a systematic manner. CONCLUSIONS: The research demonstrated that fixations and saccadic eye movements provide important insights into drivers' visual search behavior, information needs, and information acquisition processes. APPLICATION: This research has been a cornerstone for a myriad of driving-related studies, by Rockwell and other researchers. Building on Rockwell's pioneering work, these studies used eye-tracking systems to describe cognitive aspects of skill acquisition, and the effects of fatigue and other impairments on the process of attention and information gathering. A novel and potentially revolutionary application of this research is to use eye movement recordings for vehicle control and activation of in-vehicle safety systems.