The research reported here is part of a series of experiments that attempted to establish drivers' distance estimation accuracy during nighttime driving. The host car's lights are not only the host driver's main source of illumination, but also a source of distance information that other drivers use to estimate the distance between themselves and the host car's lights. To carry out this research, a photocell system was used to identify the cars' actual position. Sixty-four subjects were required to estimate a range of possible car locations from 60 to 870 m. The effects of headlight luminance and width between headlights were manipulated. More specifically, two levels of headlight luminance were used. Namely, High: 12 volts 4.4 amp. 258 lm., and Low: 8 volts 4 amp. 120 lm. There were also two levels of width -1 and 2 m.- between headlights. The results showed that subjects are really accurate at estimating the distance of moving and approaching vehicles when subjects are located in a stationary position. Width between headlights seems to play the most important role when estimating distance, while headlight luminance does not seem to play such a major role. (A) For the covering abstract of the conference see ITRD no 207828. The reprints are also available at the web - http://www.vti.se/pdf/reports/K18APart1.pdf; http://www.vti.se/pdf/reports/K18APart2.pdf and http://www.vti.se/pdf/reports/K18APart3.pdf.
Abstract