The VBA and the “clean air” 100km/h speed limit
Speed limit reductions due to elevated pollution levels are based on the air pollution control act (Immissionsschutzgesetz-Luft), which is identified as "IG-L". The air quality stations operated by the federal provinces transmit the measured pollution data to ASFINAG. These data are combined with traffic data and together tell us whether to switch IG-L on or off. The underlying algorithms and threshold values are defined by the respective federal province.