Road network as the basis for noise mapping in accordance with the EU Ambient Noise Directive includes main roads and supplementary roads
According to § 47b of the BImSchG, main roads are “Bundesfernstraße, Landesstraße or other cross-border road, each with a traffic volume of more than three million motor vehicles per year”
Supplementary roads include other roads with lower traffic and/or other categories of roads (including district and municipal roads)