Warning lights include the lights fitted by the manufacturer (headlights, stop, turn etc) and those lights fitted by the user to operating specifications afterwards. Warning lights must fulfil the following requirements to be effective and the failure of any factor will lead to confusion amongst the public.
be conspicuous, and readily seen to command attention (Paine & Fisher, p1), thus signalling the presence of the emergency vehicle
be recognisable and clearly identify the vehicle as an emergency service having special status (Green, p11).
ensure that the vehicle's size and shape is clearly defined, then indicate course and speed values so the motorists or pedestrian can avoid the vehicle.
generate an appropriate response from the motorist or pedestrian, such as moving to the side or stepping back onto the kerb.
Emergency services can successfully accomplish the warning task by:
the use of flashing, pulsing, rotating, oscillating or steady lamps to attract and hold attention, while imparting a sense of motion and urgency.
using different colour filters to provide information, and to distinguish the lights from the surrounding visual clutter.
designing the relationship between the lamps to be visually coordinated, to convey a clear message and to avoid presenting the display as chaotic.
the light output must be bright enough to be easily seen, even under direct sunlight and adverse weather conditions.
the light energy being controlled to prevent external glare and reflection that may affect the safety of the observer.