@Reinhard-32
I think the information comes from the road authorities (closed roads, due to road works, floods) = Black, and possibly via mobile data, telephones that are linked to a certain telephone mast (traffic volume), which in turn is passed on to the map managers. Are many telephones on a certain road section for a long time = stationary traffic = Red, Are many telephones on a certain road that moves slowly = slow moving and stationary traffic (yellow).