subject: Emergency Vehicle Lights Are Active Warning Devices [print this page] Passive warning devices work by using a special design or a special coloring for the emergency vehicle that needs to be identified separately from other vehicles. Even the emergency vehicle model could be completely different under this system or it may be painted by bold signs, colors, or lettering, to make it stand apart from the group. As different from this, active warning devices, under which category emergency vehicle lights are included, are more in use these days and rely on high intensity lights and flash patterns to increase visibility and capture the attention of other vehicles.
Painting the emergency vehicle in what is known as checkerboard patterns, also known as Battenburg markings is a form of passive warning system. This is very much in use in the emergency vehicles in the United Kingdom. These are high visibility markings consisting of alternating rows of retro-reflective squares of two colors. The colors blue, green, yellow, and red are more commonly used for this, as in the case of emergency vehicle lights as well.
In The United Kingdom yellow and blue squares are used on police vehicles, yellow and green on ambulances, and yellow and red on fire service vehicles. Yellow is used on most emergency vehicles in combination with some other color and this is done on the basis of the findings that human eye is more sensitive to yellow and green colors during daytime and to blue and green at night. Most emergency vehicles avoid these colored squares at the back of the vehicle. The passive warning devices may be used in combination with emergency vehicle lights or without it.
At the rear of the vehicle where there is no painting in retro-reflective colors, arrowheads known as chevrons are painted in some emergency vehicles. These are pointed upwards when painted at the rear, or pointed forwards when painted on the sides. In some cases the service provided by the emergency vehicle is spelt out in reverse format on the vehicle front, thereby helping other drivers to easily read the name in the rear view mirror.
All these warning methods have different levels of effectiveness, though emergency vehicle lights are generally more effective than these passive warning devices. The underside of an emergency vehicle may also be painted in an intense orange or yellow to increase the visual impact. And on some vehicles the sides are painted in stripes to increase conspicuousness.
Even ordinary vehicles are equipped with what are known as hazard lights, which are a form of warning system during emergencies. These fall outside the category of emergency vehicle lights but are used by drivers to warn other vehicles. These lights are activated by flashing the left, right, front, and rear directional signals continuously in a phased manner. Hazard lights are used when a vehicle is likely to create a traffic hazard by having to be stopped at inappropriate places, or because it is forced to move too slowly by being a part of a rally or due to bad road or weather conditions. This is a standard warning procedure in cars.
