The reflecting devices are systems passive, intended to announce in the night or the darkness a person, an object or a zone at the risk (crossroads, turn, pedestrian passage, edges, etc).

The Catadioptre S are mainly effective whenever a Risque or a Danger must be announced to a driver equipped with a source of lighting. When they are lit by a beam of light, they return it exactly in the direction from where it comes , whatever the Angle of incidence of the ray-source, sometimes by coloring reflected light towards " the envoyeur".

Other devices, more recent, but inspired of the same optical principles, aim to as reflecting a weak part of the light received in all the directions, so as to make visible the device by others as that which lights. It is the case of the reflectors of the " type; balls of verre". On the condition of being in the field of view of an observer (human or animal) located or not in the zone lit by the headlights, they make it possible this observer to be well visually alerted by the approach of a vehicle before its arrival.

Principle

In the black, the retinal cells most effective are the Cellules in stick; If they do not allow the Vision colors which is, it, ensured by the cells in cones, the cells in stick are very sensitive to the low luminous intensities and the short interruptions of low luminous intensities. They are associated with the nerve centres of the brain which detect and interprêtent the movements in the field of view. It is they also which allow best the detection of flickerings of low intensity the night or in the black.

It is thanks to these cells that of night the fast passage of a cat, even of a mouse, in front of a reflecting device lit by the headlight of car will be perceived often better by its driver, even with several tens of meters, even with more than 100 meters, that of day;

the Cells in stick being directly connected to the centers of day before and alarm brain, the attention of that which looks at is activated by the least effect of flickering or obliteration of the luminous point by a person, animal or object who would pass between this point and the eye.

Moreover it is the periphery of the Rétine which is richest in cells in stick. However, this zone of the retina collects the light coming from the periphery of the field of vision. This contributes to make the device particularly effective for the Road safety.

Four complementary approaches

One can distinguish four great types of devices reflecting,

- Descriptive : Certain control panels of Road safety are manufactured with pigments containing of the microballs of glass or reflective materials. One also spreads out a layer of powder (microballs of glass) over white painting materializing on the ground the passages pedestrians.

- fixed Devices placed on objects or roads to materialize a tread or the presence of these objects. They were initially simple reflectors or reflective stringcourses, which recently evolved to systems more sophisticated out of glass (cf illustrations)

- carried devices , fixed on vehicles, for example with the back and/or in front of the bicycles, Mobylettes, or with the back of the cars, or on the rays of a bicycle or the pedals. (in these the last two cases, the movement of the wheel or the pedal makes the device even more visible). It is generally Catadioptre S, to which one adds sometimes reflective bands (or known as reflecting or réflectorisantes ).

- devices carried by a person , fixed on clothing, shoes, portfolios, in a permanent way (bent, stuck) or provisional (bracelet, belts, arm-band.). They contain a " pigment" who is in fact made up of microballs of glass or materials having close optical properties, which reflect the light.

Materials

By materials and the forms used, the manufacturers seek the best index of luminous reflection, by limiting the losses of intensity by diffusion or absorption in material. The primary products are varied and adapted to various uses. As examples, one finds in the trade:

- devices containing glass

- micro balls of glass playing the part of reflective pigment,

- small balls of glass inserted in a base,

- special form of glass a few centimetres in diameter and thickness inserted in the road or the ground of the place.

- rigid plastic

- flexible plastic (bracelets, Scotch tape, stickers, etc)

- metal coated (ex control panel)

- paintings

- or fabrics technical

Colors

the reflective arm-bands and elements for clothing return an often white, yellow light fluo or orange fluo, colors conventionally associated with the indication of the risk.

the mobile devices furnishing the cycles or other vehicles are by convention reds (with the back) and/or orange (for the sides or the pedals of bicycles or motor cycles).

Of the similar devices, containing an orange or red reflector can be fixed on the edges of doors of vehicles or inside, so as to make them more visible, in particular for the open doors of a stopped vehicle in the black.

the fixed devices on the ground return a white light (for white headlights) which is most useful and effective, because best perceived by the cells in sticks.

Legislation

Some of these devices are obligatory, on the vehicles in particular and must be maintained clean and visible.

In the majority of the countries, it does not have there obligation concerning clothing or portfolios of children whereas their safety could be very improved by a visibility increased in the black.

Certaines great communities regularly offer to the children schools, to the cyclists or to the inhabitants of the arm-bands or reflective bracelets, but they are carried finally rather little. These objects are sometimes used as advertizing medium.

Ecological interest

They are solid and durable passive safety devices. They require neither large work for the installation, neither energy source, nor machine elements (not of risk of breakdown. They must simply remain clean and visible). For the devices of glass and plastic, they are easy to destroy at the end of the lifetime, even potentially which can be recycled and reusable.

- the devices out of glass or plastic do not seem to pose of environmental problem.

- a écobilan remains to be made for the fabric bands, plastic, etc who would take account of the pigments and the durability of the products. But these devices seem in all the cases much more interesting in ecological term of Empreinte than all the other solutions, for which they cannot be always substituted, but which themselves could also improve their environmental and cost-benefit assessment.

It is one of the most interesting solutions to reduce the ecological impacts of the roads, transport and the illumination on the night environment.

These devices do not produce a luminous Pollution and seem the least perturbing for fauna. They do not contribute to the halations which are a harmful effect for the practice of astronomy or the pleasure of admiring the night sky. North-American studies relating to the phenomenon of Roadkill showed that reflectors returning part of the light towards the accesses could decrease animal mortality on the road in " alertant" mammals being on the point of crossing a road of night whereas a vehicle approaches, but this device loses of its effectiveness at dawn and laying down sun, hours when the collisions are most numerous.

the devices of glass seem less at the risk for the environment.

Internal bonds

• luminous Pollution
• Vision
• Reflector
• Sustainable development
• Safety
• Risk management

External bonds

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