Abstract
Headway monitors are thought to have a potential to improve driving safety and reduce driver's strain. To investigate their effects on driving behaviors, a series of experiments using a driving simulator were conducted. Four different monitor types were compared: (a)numerical character type, (b)horizontal bar-graph type, (c)monochrome perspective figure type, and (d)color perspective figure type. We propose four indexes to evaluate the monitors in the following aspects: (1)safety margin in headway distances, (2)recognition of degree of approaching, (3)driver's distraction by the monitors, and (4)driving strain in car-following. The experimental results revealed that the "color perspective figure" type monitor was ranked highest in all those aspects and proved to be effective both in improving safety and mitigating strain.