Abstract
In the present research, first, sighting distance in steadily straight running was measured by the "slit method". Next, sighting distance and sighting angle in various curvilinear running's were measured by use of a "sight point camera" devised by the authors. Introducing the conception of sighting distance and sighting angle, dynamics of the driver-vehicle system is contrived. Theoretical calculation showed that sighting distance should be longer than a certain critical value to make the system stable.