Комментарии к CAF Urbos 100 № 6001

Utrecht is a (positive) exception. In the not-so-distant past, there were many line numbers in Charleroi, some of which were only used very occasionally. The drivers then used either no indication ('special') or an incorrect one, and a remark (usually made by a tram photographer) always resulted in the answer: 'those who use my tram know where it goes and the rest has no business with it'.
The use of colors and symbols may seem complicated to the outsiders, but it is not: it is based on districts (plural) and thus the final destination of the vehicle.
Unfortunately, this system develops as quickly as the network changes - and it does so regularly.
The use of symbols would not be consistently implemented (but retained where possible) and there was no way out with the line colors either: 'high-value' bus lines were added and had to be given a separate color, thus negating the whole principle.
In fact: about the same as in Alexandria... So they are initially very good intentions, but when the network changes, they prove more and more difficult to maintain.
This was the initial list of the colors and symbols:

Rood (red) - Domtoren (tower): Centraal Station, Museumkwartier
Oranje (orange) - Zon (sun): De Uithof
Geel (yellow) - Ruit (diamond): Lunetten, Houten, Bunnik, Wijk bij Duurstede
Groen (green) Pijl (arrow): Nieuwegein, IJsselstein, Vianen, Leerdam
Licht blauw (light blue) - Zuil (column): Zuilen, Overvecht, Tuindorp, Maarssen-Dorp
Donker blauw (dark blue) - Boogbrug (arch bridge): Leidsche Rijn, Vleuten, Lage Weide, Maarssenbroek
Paars (purple)- Huis (house): Oudwijk, Voordorp, Rijnsweerd, Zeist, De Bilt, Bilthoven, Amersfoort
Roze (pink) - Koffer (suitcase): Lombok, Kanaleneiland, Papendorp, De Meern

So the concept was a symbol and line colour for each district.
As stated above, this system will probably slowly disappear: a pity, because it could be useful for certain users.

Thanks for your detailed answer! I absolutely forgot about the example with Alexandria. Do you know by the way how many characters are used in Utrecht? 6? Two for each direction of three routes?
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It is very comical the situation. One of the best tram systems in Europe cares about inclusion in the city life of every person, while Russian urbanists indignantly stomp their feet and argue that even the route lights of Amsterdam are an anachronism. :)

This is an excellent question.
https://transphoto.org/photo/1474944/
https://transphoto.org/photo/1474922/
Historically, line colors were introduced (in Europe) around 1900 for illiterates: not everyone could go to school then.
The line colors were later retained for clarity, so that one could see from afar which line it was.
With the arrival of displays, this principle disappeared, but the newer displays can also produce colors.
Now, minorities are also taken into account: there are people who are color-blind and cannot read Latin letters or numbers.
So for them, a symbol is added to the display.
It is not absurd at all:
https://transphoto.org/photo/664668/
https://transphoto.org/photo/459608/
I am illiterate in Egypt (and I think many of the users here) and the use of colored shapes (actually symbols) for each route made my life a little easier when I visited the city of Alexandria.
Of course, they also have to be used consistently, and that's another story there...
Such an additional symbol is therefore very rare (few tram companies use it) but it can be useful for certain passengers.
Amsterdam, by the way, has been using this system per route number and not per direction since ages: more or less like Alexandria.

Нужна пояснительная бригада!
Что значат солнышко, башенка, стрелочка рядом с номером маршрута?