Motorists who are approaching a bus which is picking up or dropping off school children should be alert to the possibility of children crossing the road. In country areas of New South Wales the motorists may be travelling at speeds around 100km/h. At this speed the warning signal should be readily seen at 250 metres in order for the motorist to be able to detect and react to the signal and to slow down Without heavy braking. In bright daylight conventional vehicle signalling systems, such as direction indicator lamps, do not provide this required signal range. Traffic signals practice suggests that much brighter lights are required.

A dilemma is that bright warning lights might cause discomfort and glare at dusk or at night The authors examined the geometry of a typical scenario for a car encountering a bus at the side of the road. It was found that a warning light system could be specified which achieved the required signal range but which, due to its high mounting position on the bus and sharp vertical cut-off of the light distribution downwards, enabled motorists to move into a lower intensity portion of the beam as they approached the bus.