Australians Cite Reasons To Endorse Lime-Yellow
features
A recent Australian study on the identification of emergency vehicles by motorists and emergency vehicle warning systems endorses the decision of many American fire departments to the use of lime-yellow for their apparatus.
On the road, vision is the single most important human sense, so we must utilize this to develop an optimum standard for the safety of emergency we (at rest or moving), the vehicle’s position on the road and the special priority it requires. This must be done in all weather and light conditions.
There are two phases in the reaction to emergency vehicles: (1) the motorist becoming aware of the presence of the vehicle, e.g., by the sound of a siren; and (2) searching for and locating the emergency vehicle to either avoid it or allow it the right of way.
The study concentrates on the second phase of this operation, pointing out the need for the emergency vehicle to be highly conspicuous at all times to assist drivers in seeing it and drawing their attention to it. The aim is to allow drivers to rapidly pick out the emergency vehicle from surrounding traffic even in high traffic densities in poor light, and to react to the vehicle in minimum time. This can be best achieved by correct use of color and lights.
The principal means of achieving high visual conspicuousness is to examine the response of the human visual system to determine the range of colors to which the eye is most sensitive. Surveying the literature, the study found that in day and night conditions the eye is particularly sensitive to colors in the yellowgreen part of the spectrum.
The study also touches on other factors of the benefit of yellow colors such as psychological suitability, maintaining appearance under a wide range of street lighting and attention-attracting qualities even in fog, snow, rain, etc. Its greater visibility than red at night is also discussed.
Examination of the colors typical on emergency vehicles—red or white—by the study reveals the general unsuitability of these colors for emergency vehicles.
Red is a dark color—especially in shaded conditions. It has the same effect on people as do the emotions of fear and anger, tending to reduce stability and impair rational judgment. Furthermore, a report is mentioned which indicates that the hearing of loud sounds, such as a siren, reduces the eye’s already low sensitivity to reds. Yellow-green colors are not affected.
White, the other common color, has disadvantages in that it completely lacks attention-attracting value. It is neutral and has no impact on the street scene. It has obvious disadvantages when viewed against new snow as well as in inclement weather when it tends to blend with the colorless background.
An important aspect of assuring high visual impact emergency vehicles is to arrange for one color to cover the entire surface of the vehicle. The use of other colors in stripes or patches, etc., disrupts the shape of the vehicle and can camouflage it. The lack of continuity decreases the conspicuity of the vehicle. The best—and cheapest—solution is to use a single high-visibility color with a minimum of extraneous detail and lettering.
English experience
In Coventry, England, where the high-visibility concept was originated by the Coventry Fire Brigade, it was found that bright greenish-yellow trucks were able to get through the traffic far more quickly than when they were red. Other brigades have also had a similar result along with a drop in the accident rate for their apparatus.
The study also discusses warning lights at some length, mentioning the way warning lights should function, their role and the performance that should be sought.
The function of warning lights is to identify the vehicle as an emergency vehicle that requires special attention from motorists. In doing this, the lights should define the extremities of the vehicle by indicating the width of the vehicle as well as its front and rear.
To achieve the maximum delivery of information about the vehicle’s position and motion, it is necessary for the warning lights to be synchronized to as great a degree as possible. It is also an advantage when they present a a symmetrical moving sequence of light flashes. If this is not done, the display becomes nothing more than a confusing array of random light flashes.
Recommendations
The study makes some color recommendations, noting the need for universal use of a highly conspicuous color for all emergency vehicles uninterrupted by other colors or stripes. The most appropriate color is a bright greenishyellow, such as that which is widely known in the United States as limeyellow.
The warning light recommendations are that a system of synchronized rotating or flashing lights be used so that from any viewpoint, that part of the vehicle closest to the observer will be marked by a warning light and that the width of the vehicle at both ends be clearly indicated. Confusion must be avoided.
A copy of the updated version of this study, “Emergency Vehicle Warning Systems and Identification,” may be obtained by writing on an official letterhead to: David A. Green, N.S.W. Public Works Department, T22 State Office Block, Phillip Street, Sydney, N.S.W. 2000, Australia.
