Mary Lynn Mefford

HIGH-BEAM HEADLAMP USAGE ON UNLIGHTED RURAL ROADWAYS

In a survey conducted over 34 years ago, researchers found that drivers in the United States underuse their high beams in circumstances in which their use is prudent and advisable. High-beam use was also found to be inversely related to traffic density. Since that time, changes in beam pattern design, dimming controls, and perhaps driver awareness of the hazards of limited visibility may have sufficiently altered the driver behaviour to warrant a follow-up investigation. A survey of high-beam headlamp use was conducted on three unlit local roadways in the Ann Arbor area. Observers judged whether vehicles that were clear of both oncoming and preceding traffic, had their high or low beams turned on. Illuminance measures at approximate beam pattern locations were also recorded to support beam judgments. In addition, traffic density was estimated over 15-min intervals so that the relationship between beam use and traffic density could be examined. The results suggest that the pattern of high-beam underuse is similar to that observed in the late 1960s.

Consumer Acceptance of Adaptive Cruise Control following Experience with a Prototype System

Reactions to adaptive cruise control (ACC) were solicited from drivers following use of an ACC equipped vehicle for one hour in an actual highway environment. Participants impressions were obtained through questionnaires, administered immediately following the exposure, and later in focus groups. Individuals of varying age and conventional cruise control usage took part in the study. The issues of comfort, safety, ease-of-use, and estimated worth were addressed. While participants offered favorable responses towards ACC, despite having limited safety concerns, they were willing to pay surprisingly little for the added convenience provided. The issues of driver over-dependency on technology, system reliability, and customized features appear to warrant additional investigation to overcome consumers hesitation towards purchasing and using ACC and similar forms of advanced vehicle control systems.

DRIVING PERFORMANCE WITH AND PREFERENCE FOR HIGH-INTENSITY DISCHARGE HEADLAMPS

This in-traffic study evaluated driving performance with and preference for high-intensity discharge (HID) low beam headlamps. Subjects drove two identical luxury sedans. One vehicle was equipped with HID low beams and the other with tungsten halogen low beams. The main difference between the two beams was that the HID lamps provided more spread light. Driving performance was evaluated by analysing steering frequencies. The hypothesis was that the wider beam pattern of the HID lamps would be beneficial by reducing the steering effort in the 0.3-0.6 Hz range, which has been used in previous studies as an index of steering-task difficulty. The main finding is that the wider HID beam pattern made lane maintenance less demanding, as measured by a reduction in the steering frequencies between 0.3 and 0.6 Hz. The implication is that HID headlamps may be beneficial to safety, because their wider beam pattern allows more of the limited information processing resources of drivers to be allocated to other tasks. When the subjects were not primed before driving to pay attention to the headlamps, they did not show, as a group, preference for either type of lamp. However, when they were told to pay attention to the headlamps, they overwhelmingly preferred the HID lamps.