Michael Sivak

Cross-cultural differences in driver self-assessment.

This study investigated differences in driver self-assessment among U.S., Spanish, and West German drivers. Subjects responded to 14 questions that used five-point semantic scales dealing with driver performance and abilities. Pairs of questions, concerning the same driving-related aspects, differed by requesting a self-assessment on an absolute basis and in relation to the average driver. The subjects in all three countries included younger, middle-aged, and older drivers of both sexes. The following are the main findings: (1) a majority of drivers in each country rated themselves positively on all driving-related scales studied; (2) significant effects of country, age group, and sex of the subjects were present for several of the scales; (3) some of these effects remained significant even after controlling for the differential driving experience. For example, U.S. drivers assessed themselves as safer than did West German and Spanish subjects, younger subjects less wise than middle-aged and older subjects, and males more relaxed than females.

Glare From Automobile Rear-Vision Mirrors

Four studies were carried out to measure disability and discomfort glare from automotive rear-view mirrors. The results of the first three studies, which were concerned with disability effects, indicated that there are significant losses in forward visibility even at glare levels associated with low-beam headlamps. The last study measured comfort levels and showed that drivers rated even moderate glare levels uncomfortable, especially if they were exposed to them for a relatively long period of time. The implications of these findings for headlamp design are discussed.

Cross-cultural differences in driver risk-taking

This study investigated differences in simulated driver risk-taking behavior among U.S., Spanish, and West German subjects. The task consisted of performing a simulated intersection crossing on a video display. Subjects were shown an intersection with moving traffic on a horizontal road, and they were asked to attempt (under time pressure) a fixed number of crossings with a car moving vertically. The subjects in all three countries included younger, middle-aged, and older persons of both sexes. The following are the main findings: (1) The performance of West German subjects tended to differ from those of U.S. and Spanish subjects. Specifically, West German subjects attempted fewer crossings, had a higher probability of success, and had greater safety margins. (2) Target risk-level of performance, measured by probability of successful crossings, was not affected by age or sex. (3) Probability of attempted crossings was greater for males and younger subjects than for females and older subjects. (4) Similarly, safety margins during attempted crossings were smaller for males and younger subjects than for females and older subjects. These results suggest that there are differences among countries in the target risk-level of performance. However, the present findings imply that within each country all subjects (regardless of age and sex) tended to have the same target risk-level. To attain this risk-level of performance, males and younger subjects (because of their presumed superior psychomotor skills and/or greater experience with video tasks) attempted to cross more gaps (and, consequently, smaller gaps), with resulting smaller safety margins.

DISCOMFORT GLARE FROM AUTOMOBILE HEADLIGHTS

Three studies are described concerning discomfort glare arising from automotive headlamps. Two issues were of principle concern, (1) the so-called “range effect,” and (2) the relationship between laboratory and field findings concerning glare. The first study was conducted in a laboratory and was designed to evaluate the range effect and subject age. A significant range effect was found. Older subjects were more sensitive to glare than young subjects, but the effects were small except at very high glare levels. The second study compared glare ratings using the 9-interval DeBoer scale and a simple 3-interval scale. Results are described. The third study compared ratings predicted based on laboratory data with those obtained in a full-scale vehicle meeting situation. The latter ratings were much more comfortable than predicted from laboratory data, except at very high intensities. A significant range effect was found as well.

Effect of headlamp area on discomfort glare

This laboratory study evaluated the effect of the size of the glare source on discomfort glare. The subjects performed two simultaneous tasks: continuous compensatory tracking, and evaluation of discomfort from glare stimuli presented periodically in the near visual periphery. The glare stimuli were circles of two sizes (approximately 0.3 and 0.6° in diameter), and produced five illuminance levels (from 0.03 to 3.1 lux) at the observers eye. Subjects used a nine-point response scale to evaluate discomfort glare. The results indicate that there was a small but statistically significant effect of the size of glare source, with the smaller glare stimuli resulting in more discomfort glare. The mean difference over the range of glare illuminances tested was 0.2 points on the nine-point response scale.

Motor vehicle forward lighting

This paper surveys the literature on motor vehicle headlighting and its influence on the ability of drivers to avoid accidents. The review identifies the key relationships between headlamp design characteristics and driver and environmental factors. The major safety problems associated with headlighting are discussed, and issues needing the attention of the research community are identified.

MOTOR VEHICLE REAR LIGHTING AND SIGNALING

This paper addresses the relationship between vehicle rear lighting and signaling systems and probability of accident involvement. All classes of vehicles and all aspects of rear lighting and signaling systems as specified in current standards are considered in terms of the informational needs of following drivers. Relevant vehicle, driver, and environmental characteristics are identified, and their frequency of occurrence and relationship to accidents (or pertinent proxies) discussed whenever such information is available. The bulk of the report is devoted to reviewing, summarizing, and integrating the large body of data concerning vehicle rear lighting and signaling systems, including engineering analyses and other analytical studies, as well as experimental data from laboratory, simulation and field studies. The major output of this review and summary is the identification of: 1) the major problems associated with vehicle rear lighting and signaling systems, 2) mitigating concepts, including a discussion of how these concepts should be evaluated, and 3) considerations for the future attention of the research community interested in improving vehicle rear lighting and signaling systems.

MULTIPLE ERGONOMIC INTERVENTIONS AND TRANSPORTATION SAFETY

This article discusses arguments and research evidence concerning multiple ergonomic approaches to problems of transportation safety. Transportation accidents ( and their consequences) are the result of multifactor processes. Therefore, the probability of an- accident ( and of an injury, given an accident) can be influenced by interventions directed at any of the factors. Furthermore, the most effective accident countermeasures are not necessarily those directed at the ‘ cause’ of accidents. As examples, multiple ergonomic countermeasures are noted for road accidents involving alcohol-intoxicated drivers and elderly drivers, as well as for minimizing injuries resulting from road accidents