Below are signs for pedestrians and the style are that of road signs. The style of road signs are very familiar now and so we see this style of sign writing across signs for pedestrians. I will admit that some of these signs are both for cyclists as well, so they are in a similar sense of reason, cycling past quick.
However these signs are for just pedestrians, note they are the same style.
This one is a more personal sign yet still of the same style.
What makes these signs work well is the consistency with the type face, keeping to a set of rules general size and being larger for more of an emphasis. Also weather part or all of the sign is in upper or lower case. Primary colours is also a reason why these signs work so well in the design context.