Can Headway Reduction in Fog Be Explained by Impaired Perception of Relative Motion?

Previous studies have shown that drivers follow at a shorter headway in foggy conditions. This study investigates whether shortening the following distance could be a way for drivers to improve their perception of the headway change. Experiments were conducted to investigate response time for discriminating between whether the vehicle ahead is getting closer or farther away. Several visibility conditions were studied, ranging from a no-fog condition to a condition in which the vehicle could be seen only by its rear fog lights. Results showed that fog conditions increased response times when the outline of the vehicle was barely visible or not visible at all. The longer response times in fog were attributable to the low contrast of the vehicle outline when still visible and to the smaller spacing between the two lights when the outline could not be properly perceived. Response times also were found to be shorter for shorter following distances and for faster accelerations. These findings indicate that shortening the following distance until visibility of the lead vehicle changes from bad to good may have a perceptual control benefit in foggy conditions.


  • English

Media Info

  • Media Type: Print
  • Features: Figures; References; Tables;
  • Pagination: pp 378-392
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 01142588
  • Record Type: Publication
  • Files: TRIS, ATRI
  • Created Date: Oct 28 2009 8:44AM