Young and Old Subject Distance Between Vehicles Estimation Using Linear Distance and “Car Lengths”

Drivers perform distance estimations regarding their vehicle and objects around them (including other vehicles) continuously. Such estimates may employ linear distance or “car lengths”. The reliability of such assessments is often uncertain. The purpose of this investigation was to evaluate a subject's ability to judge distances between stationary vehicles, ranging from very close (15 ft) to 250 ft, using linear length (ft) and “car lengths” and to compare the relative accuracy of these two methods. Age influences were also investigated, grouping subjects into “young” (19-28 yrs) and “old” (64-76 yrs). This study found that the ability to estimate distance between two vehicles in the range 15 to 250 ft is limited, with subjects routinely underestimating the distance. The age influence became statistically significant at distances over 100 ft, with older subjects underestimating the distance even more than younger subjects. Finally, it was found that the length unit “car length” was even more likely to provide inaccurate distance estimations relative to linear length.