Yellow bar markings: their design and effect on driver behaviour

This paper examines the braking behaviour of drivers on approach to isolated rural intersections in order to determine the effectiveness of yellow bar markings as a speed reducing device. Approach speed profiles were measured over some 450 m to examine in detail the effect of the markings. It was found that the markings do reduce approach speeds, including the speeds of these drivers identified as approaching in the highest speed ranges. The markings do not appear to reduce speed through manipulation of the driver's visual field as was thought; rather the effect of the markings is that of a very large hazard warning device which it is virtually impossible for the driver to disregard. On the basis of the study findings it is possible to propose an installation design which maximises the effect of the device, given the better awareness of their method of operation that has been obtained (A).