A Cybernetic Perspective on Car Following in Fog

Drivers often drive at a closer time headway (THW) in fog than in clear weather conditions for similar speed ranges (White & Jeffery, 1980). Closer following is generally considered more dangerous. The hypothesis pursued in this paper is that drivers experience a perceptual-motor benefit from driving closer in fog that results in greater (or equivalent) safety and reduced driving demand. A computational car following model with an experimentally constructed perceptual module is introduced and used to demonstrate that under some conditions, closer following in fog is indeed beneficial because it effectively reduces drivers’ perceptual delay by a sufficient amount to improve controllability of the gap so much that the variability in THW reduces more than (or as much as) the adopted decrease in target THW.