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An evaluation was conducted of a mechanical beam switching system that may be appropriate for use with HID lamps. Subjects rated the adequacy of beam change time at several rates, compared with an electrical beam changing system. The results indicate that the subjects rated the mechanical and electrical systems the same, at the shortest change time for the former. Longer change times elicited poorer ratings for the mechanical system. The change from low to high beam was rated better than the change from high to low beam in the mechanical system. This difference was statistically significant at the two slower change rates investigated.

Older persons often give up or greatly reduce driving during the hours of darkness. The reason for this is apparently age-related changes in vision that are most noticeable under conditions of low illumination. This paper reviews research that shows how the nighttime visual performance of older drivers can be aided. Improvements discussed involve the detection and legibility of highway signs and the detection and identification of potential hazards such as large trucks.

LEDs have been developed that are suitable for use in automotive signal lamps. As signal light sources, LEDs have a number of advantages, among which are faster rise times, long life, flexibility in lamp size and shape, and the possibility of unique modes of presentation that may improve signal performance. The purpose of the research described in this paper was to examine driver preferences and response time to unique stop and turn signal presentations using LED sources. The results suggest that subjects preferred some of the signal modes to present-day configurations, and responded faster to them under a variety of conditions.

Glare can come from sources in front of or behind a vehicle. Most attention has been paid to the problem of glare from oncoming vehicles. Yet glare from following vehicles can be just as severe, and continue for longer periods of time. This paper examines the problem of glare from the rear view mirrors, both from a point of view of its effect on visibility and discomfort. It is shown that such effects can be quite significant. Methods of reducing the glare levels are discussed.

This report describes a test run on a device (the Advance Braking Light Device, or ABLD) that senses the rate at which the accelerator is released. If the rate is equal to or faster than a predetermined minimum the device turns on the brake lights for one second. The interest in this study was in determining whether there were any operational problems with the ABLD, and measuring the gain in brake illumination time it provides. The results suggest that there are no significant operational problems, and that the device causes the brake lights to be illuminated 0.2 to 0.3 second sooner when it is energized.

The time that it takes a driver to perceive and respond to an unexpected situation is of considerable interest to those who design the roadway system as well as in many instances of litigation resulting from motor vehicle crashes. In this paper the subject of driver perception-response time is reviewed. It begins by describing the necessary steps in perception-response, then reviews the available literature on the subject. Various factors that can affect perception-response time are covered, and recommendations are offered.

This paper examines age-related changes in the visual system that may have a significant effect on the ability to drive at night. It begins with a description of changes in the eyes that occur with age and then explains how these changes reduce the ability to see low-contrast objects and increase the effects of glare. The results of a number of studies are described. The paper concludes with a section describing certain measures that can be taken to reduce these effects.

Two studies are described evaluating high-mounted stop lamps using light-emitting diodes (LED's) compared with conventional tungsten units. The first of these studies obtained ratings from subjects who drove one car and followed another car equipped with the test units. The subjects generally liked the LED units. The second study was a laboratory evaluation of the attention-getting capabilities of LED and conventional stop lamps. Under all conditions subjects responded faster to the LED units. The response time advantage for the LED units increased with more difficult viewing conditions, such as high levels of illumination and greater viewing distance. The results of these investigations are discussed in terms of the applicability of the LED technology to high-mounted stop lamps on motor vehicles.

A nationwide survey was conducted of the condition of vehicle lighting equipment. Twenty different sites were visited and a total of nearly 1, 000 vehicles included in the sample. Headlamp aim and dirt levels were measured and the condition of marker and signal lamps noted. The results of the survey indicate that many vehicles have headlamps that are badly aimed. The condition of front and rear marker and signal lamps is generally good, with more than 98% of such units functioning. Side marker lights were in poorer shape, hut more than 90% of these were operating. Consistent differences were found between areas with and without vehicle inspection programs. It appears that such programs are effective in improving the condition of vehicle lighting systems.

This paper describes several studies of headlighting and glare effects. It starts with a seeing-distance study, the results of which show that low-beam headlighting systems do not provide adequate illumination to reliably reveal low-contrast objects at any but relatively low speeds. The major barrier to increasing headlamp output is concern over glare effects. This paper describes two studies of glare. The results suggest that judgments of glare discomfort are influenced by the range of glare stimuli to which subjects are exposed, and that people are more tolerant of glare than previous laboratory studies indicate. A reanalysis of some field glare and illumination measurements is also offered. This points out the difficulties in controlling glare under real-world operating conditions. Recommendations are offered for a program that would move toward eventual achievement by an optimum low-beam lighting system.

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.

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.

A sample population of 51 male and 57 female subjects ranging in age from 18 to 78 years was assembled and tested in six different vehicles for preferred seat positions under non-driving and driving conditions. Volunteer subjects were selected by age, stature, and weight criteria in order to match the U.S. adult population to the extent practical. Preliminary analyses of these data suggest that on a total sample basis there is little difference between seat positions selected under non-driving and driving conditions, but that individuals may show significant differences. The small differences in group mean positions observed in this study may be due to a seat belt and/or an initial seat position factor. Post-drive seat position results were analyzed in a variety of ways to identify factors that may influence a person's preferred seat position.

The literature on headlamp aiming is surveyed in detail to pinpoint the various sources and magnitudes of aim variance. Four major sources of variance are identified (differences between beam and mounting plane, photometric changes in use, long axis alignment, and human factors), along with a number of others of lesser consequence. Illustrations are offered showing the expected population variance under a variety of conditions. It is apparent that, at the present state-of-the-art, a substantial percentage of the lamp population can be expected to be beyond the limits recommended in SAE J599c. It is further apparent that this would be true regardless of whether or not a vehicle inspection program is in operation. Recommendations are given regarding research emphasis in headlighting. Ways of reducing variance from the most significant sources are considered and recommendations offered.

The measurement of drivers' performance at the limit of capability is difficult due to methodological problems, moment to moment variability of drivers, differences between drivers, and their interactions with the characteristics of the vehicle, road, and environment. Aspects of longitudinal and lateral vehicle control are discussed by reference to results of braking and steering tests, with emphasis on the variations between the performance of drivers. The effectiveness of drivers in vehicle braking is shown to be a function of the brake system deceleration/pedal force gain. Overall braking performance could also be improved by increasing the abilities of drivers who are poor in this task, by training in brake modulation on dry and wet pavements. The best drivers are as effective as an antilocking brake system, except on the equivalent of ice covered pavement. In steering control drivers increase their response frequency bandwidth as task difficulty increases.