On busses in Groningen that run a service within the city boundaries the number of the line is displayed in colour. This has as advantage that you can recognise the bus from a large distance, i.e., provided you know what colour to look for! If you don’t know, you’ll have a hard time trying to read the number, as the colour combinations are quite strange, see the pictures below
This one is actually not so bad, but still, best legible is:
Just the number.
Not just in the Netherlands, spotted in Bologna (Italy):
submitted by Dick de Waard