30 Days with less cars: The effect of a month-long car-free campaign in Flanders, Belgium

• We have created the first regional campaign targeting car use in Belgium, with 6500 participants attempting to decrease car use during June 2022. • This campaign was the first combining the large-scale behavioral change elements of a government campaign with an academic setup. • Our results show that most participants decreased their car use and switched to other modes of transportation. • The most difficult trips to not take by car were care-related trips as well as visits to friends and family. • There is no ‘one size fits all’ solution to car dependency: offer a range of information and offers for sustainable alternatives. Despite its high population density and public transport connections, cars make out 65 % of the modal share in Flanders, Belgium. Flemish car use is still increasing, despite the necessity to decrease car use for reasons linked to the environment, health, and infrastructural problems. Due to historical auto-centric policymaking, car dependency -both physically and mentally- has become ingrained in mobility behavior. To experiment with how car dependency can be diminished, the campaign ‘30 Dagen Minder Wagen’ (30 Days with Less Cars) was launched, which challenged Flemish people to not use their cars as much as possible during July 2022. 6500 people participated, with a resulting CO 2 emission decrease equal to the annual emissions of 64 cars. This was the first large-scale academic campaign oriented on mobility behavioral change in the region.