The Effect of Driver Eye Height on Speed Choice, Lane-Keeping, and Car-Following Behavior: Results of Two Driving Simulator Studies

Abstract

Objective. Two simulator studies were conducted that assessed the effect of driver eye height on speed choice, lane-keeping, and car-following behavior. The effect of eye height on the subjective variables of mental workload, frustration, and confidence was also investigated, as was the contribution of drivers' aggression.

Methods. A total of 43 participants drove a simulated route while seated at two different eye heights: one that represented the view of the road from a large SUV and one that represented the view of the road from a small sports car. Driving scenarios were comprised of both open road and car-following segments. Dependent variables included driver-selected speed, speed variability, lane position, following distance to a slower-moving lead vehicle, and the subjective variables of frustration, confidence, and mental workload.

Results. When viewing the road from a high eye height, drivers drove faster, with more variability, and were less able to maintain a consistent position within the lane than when viewing the road from a low eye height. Driver eye height did not influence following distance to a slower-moving lead vehicle. Driver aggression had no effect on any of the dependent variables except level of frustration.

Conclusions. The two studies demonstrate that, when they are not able to reference a speedometer, drivers choose to drive faster when they view the road from an eye height that is representative of a large SUV compared to that of a small sports car. There is a need to educate drivers of SUVs and other tall vehicles of this perceptual phenomenon in order to prevent collisions that may occur in conditions where it is impossible for drivers to base their speed selection solely on posted speed limits, such as in inclement weather.

Keywords:

• Road Safety
• Speeding
• Vehicle Characteristics
• Perception
• Aggression
• SUVs

ACKNOWLEDGMENTS

The author gratefully acknowledges Tara McCurdie for her efforts in running Study Two. The results from Study One were published previously, and the author would like to thank the Transportation Research Board for allowing them to be presented again here. The opinions expressed in this manuscript reflect those of its author, and are not necessarily those of Transport Canada.

Notes

¹In 1974, vehicles were classified as either “Passenger cars” or “Commercial vehicles,” which included minivans, sport-utility vehicles, light and heavy trucks, vans, and buses. Thus, this figure overestimates the percentage of light trucks and vans from this era. If this categorization were used in 2004, the percentage of “Commercial vehicles” would increase to 48%.

²The current Canadian Motor Vehicle Safety Standard for glazing materials, CMVSS 205, restricts passenger cars, but not SUVs, from having tinted rear windows.