Discontinuity effect of edge line markings on time headway in car-following

Abstract

To adjust the time headway ‘beforehand’ for collision avoidance, the impacts of a kind of designed edge line markings on time headways (THW) were studied. On-road experiment and field observations were conducted to obtain naturalistic vehicle flow data. Statistical analyses showed that (1) the THW increased in the conditions of edge line markings with horizontal offset (HOS) or longitudinal gap (LG) and (2) the THW increased along with the increase of HOS and with the decrease of LG. From the perspective of speed perception and distance perception, the results were interpreted as (1) the edge rate (ER) resulted in speed overesti-mation, which led to a reduction in actual speed, and (2) the ‘discontinuity effect’ from edge line markings with HOS and/or LG led to distance underestimation. For safety, drivers incline to increase the distance headways with results of the increase in THW. This may be a new method for preventing car-following accidents.