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The Museum
of Road Signs and Signals
and street lighting
Public lighting
Definition:
Street lighting is defined as all the lighting used in public spaces (streets, squares, motorways, etc.).
Historical background:
The idea of lighting up towns is not new. Even in Roman times, some of the largest towns were lit.
In the Middle Ages, it was mainly specific points that were lit (town gates, etc.). There was no organised public lighting, so our towns were often plunged into darkness. Nevertheless, residents were asked not to light the street, but to mark it with lanterns or candles.
In London, in 1414, the city's inhabitants were obliged to light the street from their homes (which made the lighting discontinuous). The first fixed lanterns appeared in Paris in 1667, and their management was entrusted in turn to residents appointed by the authorities. Brussels, for example, introduced street lighting in 1675.
The technical means used for public lighting, as described below, also evolved over the years in response to the need for better lighting quality.
Throughout the ages, public lighting has retained its original function: to ensure safety in the streets by means of light. For example, in July 2021, during the catastrophic floods in Wallonia (B), a major safety problem arose following the destruction of many street lamps and their lampposts. Some communes, plunged into total darkness, were confronted with acts of looting, among other things. A curfew was imposed in some parts of the country, including Trooz.Techniques:
The techniques:
used to light public spaces will evolve over time, as a result of technological discoveries on the one hand, but also according to lighting requirements (the density of car traffic, for example).
Here are a few key dates:
-Until the Middle Ages: use of candles.
-Around 1744 (Paris): the candle was abandoned in favour of the oil lamp. The reverberant lantern was born (the principle of reflecting light back towards the ground by placing a metal plate above the light point)! These lanterns were equipped with one to four wicks, depending on the intensity of light required.
-London, 1820: gas was introduced for street lighting. Major modernisation work began in London and Paris, which were transformed around 1840.
-The first electric lighting appeared in 1878, still in competition with gas. It took a few years for this technology to become widespread, spurred on by the work of Thomas Edison and the invention of the filament lamp using incandescence as the light source.
1910-1940: Electricity was introduced everywhere, and gas was dismantled (the last gas-powered equipment was dismantled in Paris in 1960).
The MuSé has set itself the task of presenting examples of luminaires deployed in Belgium since the advent of electric power, illustrating each technology over the years.
In Wallonia, 110,000 light points have to be managed at regional road level and a further 5,88235 at local authority level.
1-Incandescence:
The principle of incandescence was to make a metal filament glow red by passing an electric current through it. This technique enabled the filament to emit light. In fact, 5% of the electrical energy was converted into light and the rest into heat. The tungsten filament could reach a temperature of 2,000°C and the bulb envelope several hundred degrees. In order to work, the filament had to be insulated in an oxygen-free envelope (the "lamp"), which later came to contain halogen. The lifespan of a filament bulb was 1000 hours, perhaps as a result of agreements between manufacturers to limit it.
The filament: this was a thin wire of tungsten twisted simply, doubly or triply. Although invented before this date, it was in 1910 that the filament lamp was significantly improved: tungsten, an environment containing a noble gas.
These lamps were banned in Europe from 1 September 2009, with a total phase-out in 2012.
To illustrate this method of lighting, the MuSé has a very beautiful and rare floor lamp, the Holophane 4446, for which the documentation indicates that it was manufactured in 1925 and that the lamps used could range from 300 to 750 watts.
2-Fluorescence:
The term "neon lamp" is somewhat of a misnomer. The term "fluorescent lamp" or "fluorescent lamp" is more appropriate. This process works with discharge lamps: an electric current passes through a mixture of gases between two electrodes. This emits light. The passage of the current makes the medium unstable and electromagnetic radiation is emitted. Some of this radiation is visible to the human eye: this is light. The colour of the light depends on the gas present in the medium through which the electric current passes. In the case of fluorescent lamps, this is mercury, which produces a white light. The glass walls are coated with a fluorescent powder that transforms ultraviolet rays into visible light. Fluorescent lamps also need a certain amount of equipment, namely a ballast.
The first fluorescent lamps appeared on the market around 1936. In Paris, metro stations were lit with this technology around 1946.
Since August 2023, fluorescent lamps can no longer be sold in Europe.
The MuSé has some characteristic lanterns that work with fluorescent lamps. This is the case of this very old GN Schréder luminaire equipped with three lamps of this type and the corresponding ballasts. The MuSé also has the privilege of owning other old street lamps that once lined our roads.
You may have noticed this, especially if you have used this type of lighting in the past. The diameter of the bulb has become smaller and smaller over time. The so-called "T12" lamps (banned in 2012) had a diameter of 38 mm. They were followed by the "T8" and "T5", with diameters of 26 mm and 16 mm respectively. It was Philips that made this development possible. In 1973, it also changed the gas mixtures in the lamps, which improved light output in particular. The luminaire above was originally fitted with T12 lamps, but in the photo it is fitted with T8 lamps.
MuSé also has a luminaire fitted with a T5 lamp (49W): the Schréder FV 1. This specimen comes from the Cointe tunnel in Liège. It was saved from destruction in August 2023. Since then, the tunnel lighting has been modernised and converted to LEDs.
3-Mercury vapour:
Once again, this is a discharge lamp whose principle is to emit light when an electric current passes through an environment charged with high-pressure mercury. These lamps, also known as "fluorescent balloons", appeared on our streets around 1950. In Liège, according to our memories, these lamps appeared on the Quai de Rome in the early 1970s (the luminaire used was an ALH-1 from the German company Siemens). The light emitted was very white, with hints of blue.
In practice, fluorescent balloons were known to have a very attractive life span of between 8,000 and 12,000 hours. Over time, however, a loss of lighting efficiency was observed. The maintenance plan was to replace the lamp, not necessarily because it had broken down, but because it was no longer providing sufficient light. For those of you who remember, this lamp needed to heat up when it was switched on. The intensity of the light was not immediate.
Because of the toxicity of the gas contained in the balloons, this technology was banned by Europe in 2015.
MuSé has a number of luminaires equipped with fluorescent balloons of different wattages.
Schréder DM 1
Schréder Z18
4-Low-pressure sodium vapour:
Emblematic technology for roads and motorways in Belgium from the end of the 1960s until 2019, the start of the four-year replacement plan.
We are still using discharge lamps, but here it is vaporised sodium vapour that is the source of light. We have a particular admiration for these tubular lamps of varying lengths depending on the wattage.
The lamp presented here had an original output of 180 watts, before being revised to 131 watts. The glass envelope is very special and was the subject of a great deal of research to prevent it from being altered by vaporised alkaline sodium (borate glass). Remember that a Schréder RX luminaire on a Belgian H motorway was equipped with eight lamps, and that there was a pole every 50 metres! Our motorways were luxuriously lit!
From 1968 to 1970, Industrial Designer Maurice Deleuse imagined and designed the Rhombalux floor lamp for Schréder (Ans, Liège). At the end of the 1960s, the Belgian government decided to light all its roads with low-pressure sodium vapour, a technology identified as being energy-efficient and effective in terms of ground lighting.
Original sketch by
Mr M. Deleuse in December 2020 for the Miniature Village of Trooz.
To operate, the "low-pressure" sodium vapour lamp needed an ignition aid weighing 4.8 kilos. This auxiliary had the ability to increase the voltage in the tube, which contained neon gas (which explains the pink colour of the lamp when it was switched on). This neon gas was used to ensure electrical conduction between the lamp's two electrodes, which heated the whole assembly and gradually vaporised the sodium in the environment. As the vaporisation was gradual, road users could see that the lamp was gradually turning from pink to bright orange. It took around ten minutes for the luminaire to illuminate the road properly. The lifespan of this type of lamp was estimated at 15,000 hours (i.e. around 5 years).
Manufacturers stopped making these lamps in 2020.
Although most Belgian roads were fitted with Schréder equipment (Rhombalux, RX, GSO, GZM, VTP, TXS, etc.), MuSé prefers to illustrate this paragraph with equipment from another Belgian manufacturer: ACEC (Ateliers de Constructions Electriques de Charleroi). This is the RAM ACEC model and its characteristic pink colour when lit:
It was difficult to look at a "low pressure" sodium vapour lamp at its maximum lighting power. The government had decided to use this type of lighting because of its good efficiency. This was not the case when it came to colour rendering. That's why this technology was chosen for roads and not to highlight monuments, for example. At the time, we noticed that with this monochromatic colour spectrum, orange fluorescent jackets, which were supposed to make road users visible, were almost invisible under this lighting. The MuSé presents another emblematic luminaire for Belgian roads, the GSO from the Schréder group. Here it is photographed at full power:
5-High-pressure sodium vapour:
The first "high-pressure" sodium vapour lamps appeared in the 1970s. They are a type of discharge lamp. Their life is estimated at between 9,000 and 12,000 hours.
Once again, sodium is used to emit light. Here it is under high pressure. These lamps also contain mercury and xenon, which come into play when the lamp is switched on. Ignition was faster than with "low pressure" sodium. As the colour spectrum was broader, and no longer limited exclusively to orange, there was a better colour rendering, as well as an improvement in pure light output. This is why, in Belgium, on a roadway lit with "low pressure" sodium, users could come across sectors lit with "high pressure" sodium because of the manager's desire to highlight more dangerous areas. Thus, for example, a main road lit with "low pressure" sodium was lit with "high pressure" sodium when crossing inhabited areas (built-up areas).The principles of ignition and operation are identical to those explained above. In the 1980s, this lamp was further improved and engineers obtained a white "high-pressure" sodium vapour lamp, close to the incandescent lamp, by working on pressure and temperature, among other things.
2027 marks the end of the use of this "high-pressure" sodium vapour technology.
MuSé has a few examples of street lamps equipped with this technology. Power ratings vary up to 600 watts. Some of these lights were used on lightly trafficked roads, while others were used on major highways.
Philips 150 and
250 watts
MuSé's collections include many models of "high-pressure" sodium vapour luminaires of varying wattages. Here is another emblematic luminaire, found in Liège (Quai de la dérivation), but also in Dolembreux, as well as at the E25 motorway service area in Sprimont (where this example probably comes from).
Model photographed at Dolembreux, on the RN 30, where three examples were placed at two turning points with crossroads deemed dangerous.
GST Schréder floor lamp
August 2022
Most probably from the E25 motorway service area at Sprimont.
It is fitted with a 150-watt lamp.
August 2022
NB: it has lost its classic grey paintwork on the upper part of the bowl.
Ignition in progress,
still incomplete at this stage.
6-Internal induction:
The year was 1991, and Philips was at the helm of this rather unusual lamp, classified as a discharge lamp. In fact, the weak point of all discharge lamps is worn electrodes. In the internal induction lamp, there are no electrodes but an antenna that generates an electromagnetic field. This antenna is placed in the centre of an ovoid lamp containing low-pressure mercury vapour. Using the same principle as for fluorescent tubes, this field induces an electric current in the enclosure containing the mercury. Ultraviolet rays are produced and transformed into light by the fluorescent coating on the wall of the bulb.
This internal induction lamp has a lifespan of 70,000 hours. It was expensive and reserved for areas that were particularly difficult for maintenance personnel to access. The light produced was white.
According to our research, it is possible that these lamps were banned in 2017.
These lamps are rather rare, given their cost. The MuSé does, however, have a working lamp fitted with this equipment, found at Fosses-La-Ville.
Albany Urbis floor lamp
Schréder
7-Metal halides:
Another discharge lamp technology that appeared around 1994, for the version used in public lighting. The light is white, from "cool" white to "warm" white. They have a life of around 15,000 hours.
As a discharge lamp, it needs a starting gas. It is described as having a lower light output than a "high-pressure" sodium vapour lamp. It cannot operate if connected directly to the power supply, so it needs an ignition aid. In addition to road lighting, this technology is also used to enhance sites and monuments.
This type of lamp is often referred to as "metal halide". It is not yet banned in Europe, and its use has been extended until 2027.
As with previous light sources, the MuSé has a number of luminaires equipped with this type of lamp.
Luminaire Bega 8141
Lampe Philips de 70watts
8-The LED:
The light-emitting diode made a major appearance in 2010. Although LEDs already existed in the mid-1980s, their performance was not yet exceptional and only the colours red, green and yellow were available. Dazzling progress in the early 2000s led to the emergence of the intense white LED. The principle behind the LED is the production of light by a semiconductor material when an electric current is passed through it. A semiconductor is a specific material that responds to physical principles that enable it to emit light when an electric current is passed through it.
LEDs have therefore become the main medium used in public lighting... It has also replaced all the other techniques described above. It offers many significant advantages:
-It consumes little electricity.
-It is more directional, and therefore greatly reduces light pollution.
-It respects the flora and fauna along illuminated roadways.
-It requires less equipment to operate.
-It heats up very little.
-It has an estimated lifespan of 100,000 hours.
It is also possible to vary the intensity according to the hours of illumination and the intensity of the traffic.
The MuSé has a number of LED lights, some of them purely functional, others ornamental.
Lampadaire Albany Led Schréder
Lampadaire Luma 2 Philips
Lighting columns: concrete or metal?
As technology became ever more advanced, lighting designers also looked at the question of the lampposts that would support the light sources... In 1950, at the road congress in Jambes (Namur), the reinforced concrete lamppost was presented in various finishes. Concrete was the material of choice because it was inexpensive, resistant to seaside conditions and to corrosive attacks from industrial sites. Galvanised metal, at the time, was inaccessible and required regular maintenance and painting. Concrete working techniques made it possible to build high lampposts and masts with a satisfactory advance of the light source.
The motorway network and main roads were equipped with these concrete lampposts in the 1970s. Although there was no publicity on the subject, it seems that between 1973 and 1979, the concrete poles showed major weaknesses, leading to their replacement by metal lampposts, and in some cases to them falling and causing accidents.
The motorway sections of the E25 (formerly E9) opened between Chênée and Tilff-Cortil in 1977 were equipped with concrete lampposts topped with Schréder Rx H-shaped reinforcement. During the earthquake that hit Liège on 8 November 1983, many of these concrete poles were thrown off balance. It was therefore decided to knock them down as a matter of urgency, before replacing them with metal poles.
The first concrete lampposts appeared in 1947, but they didn't appeal to many people. They were made from reinforced concrete. Later, pre-stressed concrete made its appearance, making it possible to manufacture longer poles (up to 10 metres above ground level).
MuSé's mission is to save the street lamps that, among other things, preceded the introduction of LEDs in Belgium. Its collection is constantly expanding... So make sure you pay a visit to find out more!
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