City street experiments and system change Identifying barriers and enablers to the transformative process

City street experiments continue to be employed as a tool to improve urban mobility and liveability. Despite growing popularity, understanding of this transformative process, and more specifically, the barriers and enablers that exist for street experiments aiming to cause system change, remains an important knowledge gap. By way of a systematic search and review of 17 empirical studies, barriers and enablers to the transformative process are identified. Enablers include embedding experiments in long-term policies including stakeholders, active promotion and institutional support. Barriers include those within the experiment's control (a lack of required resources, unconducive design, lack of clear vision and low frequency) as well as those out of the experiment's control (opposition from stakeholders and institutional regulations and processes). The relationships between these enablers and barriers are recounted, revealing concrete recommendations for experiment organizers as well as two dilemmas for consideration.