Large scale change of traffic_sign to traffic_sign:id

[yopaseopor]

@UrbanUnPlanner

Highway authorities in the US are free to invent word-message traffic signs on an ad-hoc, “as needed” basis

Here is the same. Under hazard=undefined (ES:P50), with a complementary traffic sign (ES:S860) you can put in the plaque whatever you want. But this doesn’t mean inventing a traffic sign, nor a code also.

@UrbanUnPlanner

are still subject to MUTCD rules on shape, color, and permissible abbreviations

So this is not an invention, you can change the text but not the shape (have meaning), the color (have meaning) and permissible abbreviations (to make it compatible with all the other complementary signs)

@UrbanUnPlanner

make it necessary to provide road users with ADDITIONAL regulatory, warning, or guidance information

You say it.