it sounds like you're from britain and you are telling that all german dlc's need to be on the koln-aachen route that is kinda like saying: because the class 377 is a uk train it also needs to be on great western express; but it isn't there because the 377 doesn't drive on underground routes just like you dont see a bwegt (breisgau s-bahn) train in berlin HBF not all trains drive to all stations