Examples of LED application in signalling

Details about only two LED applications from technical and economical angles for the region’s traffic lights or for signage.

The Brussels-Capital Region is replete with companies that design, manufacture,
Install or market products based on LEDs for emergency vehicles, road signals,
Signage, lighting and even Christmas decorations

4.1 The LED traffic lights of the Brussels Capital Region
Most of the world’s large cities are slowly replacing their incandescent traffic lights with LED traffic lights.
Brussels- Capital, the first region in the country to replace the incandescent bulb based traffic lights by LED traffic lights

Brussels Capital was the first Belgian region to switch to LED traffic lights. The Region manages around 600 crossroads with traffic lights, which means, 24000 light units.

During renovations and the installation of new lights, the Service des Techniques Speciales de I’Administration de I’Equipement et des Deplacements replaces the incandescent halogen lamps with LED units. As of date 3000 LED units have been installed.

4.2 With LEDs: drastic reduction in energy consumption
The 10W LED units (42V supply voltage ) use 6 times less energy than the 60 w incandescent sources (220v supply voltage).

4.3 With LEDs: drastic reduction in maintenance costs
→For safety reasons, the incandescent lamps are replaced 3 times per year (after approximately 1200 hours of operation for a life span estimated at 3000 hours),which is a cost of EUR 1.4/unit including the replacement of the light source and cleaning the unit.
→The LED light sources are guaranteed for 5 years by their manufacturer. It is presumed that there shall be o replacement during the first 10 years. The region therefore only incurs the cleaning expenses, that is, EUR 0.6/unit, 3 times per year.
The first LED lights were installed by the Region 2 years ago and so far no unit has had to be replaced.

4.4 With LED units, there is increased safety on crossroads
In addition to saving on energy and maintenance costs by using LEDs instead of incandescent light sources, safety at crossroads also increases by installing the LED units:
→Greater reliability of LEDs and therefore the reduction in the risk of light source failure contributes to the safety of crossroads. Moreover, the LED units have several LEDs, when one source malfunctions he others continue to light, preventing any interruption in the operation of traffic lights.
→Almost instantaneous lighting of the LED source allows the automobile driver to have a faster reaction to the alternatin changes.
→The luminous flux is greater with LEDs than with incandescent sources. The LED directly emits a monochromatic light of the desired color without needing filters.
→In addition, to fight against the phantom effect (or infra) the lens of the incandescent lights is designed to absorb sunrays that fall on the light along with the absorption of luminous
flux emitted by the incandescent light source. Since the LED units are less prone to phantom effect, the transmittance of the lens can be better. In the sources studied by the Katholieke Hogeschool Sint-Lieven (KAHO), the light intensity of the LED traffic light units is 4 times greater(13) than that of incandescent traffic lights making them more perceptible to the user.
he phantom effect is reduced. The phantom effect results from the reflection of incident sunlight by reflectors encircling the light module, mainly when the sun is facing the module.
In case of phantom effect, the sunrays reflect within the unit and are reflected back through being able to make out the phase of light.
The phantom effect is higher in the incandescent units that have large reflector surrounding the lamp than in the LED units where the source reflectors are very small. Moreover, the LED units generate a higher flux (see above) which simply identifying the light phase.