Pop-up cycling infrastructure as a niche innovation for sustainable transportation in European cities: An inter- and transdisciplinary case study of Berlin

•Air quality measurements show that pop-up bike lanes reduce cyclists’ exposure to NO2.•Survey data shows high social acceptance for pop-up bike lanes.•Usage data reveals 73% increase in cycling on the pop-up bike lane.•Pre-existing multi-actor collaboration enabled fast infrastructure implementation.•Pop-up bike lanes can accelerate the implementation of the mobility transition.