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The Museum
of Road Signs and Signals
and street lighting
La signalisation
horizontale
Definition:
Road markings include all coloured markings painted directly on the road. By "markings" we mean all signs painted or stuck on a roadway, the purpose of which is to indicate traffic directions unambiguously to users.
Historical background:
The purpose of road markings is to indicate to users the direction of traffic flow, for example, but also specific indications.
It seems that we have to go back to the United States to find the origin of road markings. We're talking about 1907, so road markings are a very old principle. According to the documentation, it was initially the "STOP" signs that were accentuated by marks painted on the road. Around 1911, New York City decided to paint pedestrian crossings on its main roads. The central white line is also used to differentiate traffic flow, especially at junctions and bends. Looking at road markings also means taking an interest in an innovative idea by Rudolphe Potters in 1914, when he imagined adding glass microbeads to road paint to increase visibility at night (see also "Vertical signage"). Mr Potters' glass beads appeared on roads around 1934.
In France, paint was first used on roads in 1934; it was yellow. The first white line was drawn in England, at Sutton Colfield, in 1921.1971, the year of change... At least to comply with the decisions of the 1968 Vienna Convention on the Unification and Harmonisation of Road Signs and Signals: the lines became white, the contrast being greater than with the colour yellow, day and night. In the United States, white was replaced by yellow.
Today, white is still the rule, with yellow used for temporary markings. Other colours are also possible, but they must comply with very strict rules: blue for parking, for example. Increasingly sophisticated techniques also allow reproductions of road signs to be stuck to the ground.
Finally, since 2023, phosphorescent markings have been tested on certain roads. Phosphorescent markings store light during the day and release it again at night. The idea is to use it on roads with little or no lighting.
Road markings and retroreflection:
Road markings are therefore characterised by the principle of retroreflection. This quality is obtained by adding glass microbeads to the paint or thermoplastic material.
Here's a sample of structured thermoplastic marking, applied hot (160 to 180°). You can see microbeads on the surface of the material. In fact, there are microbeads in the material itself, but when the marking is applied, the machine projects microbeads onto the surface of the marking so that it is immediately retroreflective. Subsequently, with wear and tear, it is the internal microbeads that take on this role.
There are different grit sizes available. Road marking is a real art, and you need to ensure the right climatic conditions, for example. In some cases, it is necessary to add a drying accelerator (paint markings). In this photo, you can see a tube with brown marks: this is the drying accelerator. Other additives can also be added to give the markings a rougher finish, for example.
Road marking techniques:
Broadly speaking, there are several methods of road marking:
Hot paint or thermoplastic is sprayed onto the floor. The marking is either embossed (as in this photo) or continuous. The advantage of embossed marking is that it remains retro-reflective in rain.
The marking can also be cold-glued, as in this example of a structured surface.
Stencilling is another alternative when a symbol needs to be printed on the ground. The stencil is used for markings with paint or thermoplastic material.
Manufacturers also provide preformed markings for hot-fitting. These can be numbers or road signs repeated on the ground. Different colours are available. The markings are placed hot using a gas torch.
Microbeads, a controlled product of excellence:
The retroreflection performance of a product depends on the high quality of the microbeads it contains. These are these microbeads which, due to their spherical appearance, react like magnifying glasses and reflect light in the direction of the source.
The quality tests presented here show two results: the first, the top photo, is correct, the beads are spherical. As for the second test, photo below, we note a problem because there is a small mass of glass, not spherical, likely to disturb the retroreflection of the light.
Historical road markings in Belgium:
According to our research, the nails used to mark pedestrian crossings and traffic lanes existed even before the Second World War (1930s). They continued to exist long after the war, as we found them in rue Grétry in Liège in 1968. We also found them in rue F. Nyst in Liège in 2022 (photo left), under the layer of tar applied to the cobblestones.
Thanks to the Department of Works of the City of Liège, the MuSé has managed to save around ten nails from the rue F. Nyst during its complete renovation in March 2024. They are made of aluminium and are 10 cm in diameter. There were obviously two types. These nails were inserted into the pavement between the cobblestones, which suggests that the markings were made at the same time as the paving of the street.
They sometimes coexisted with the new system of painted stripes on the ground, as in this photo of the Place Saint Lambert in Liège in 1969. Note that these nails can be seen in the background of the photo; in the foreground, we can see a modern pedestrian crossing for the time, made up of white and yellow lines.
The first Belgian motorways had a double marking: white in the centre of the carriageway and yellow for the edge marking. On other roads, the edge markings could consist of two yellow lines. After 1975, the edge markings became standard on all national roads and became white and continuous.
In 1950, the track selection arrows were also white. It was probably only in the early 1970s that they changed shape.
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