Stevens and colleagues study temporary urbanism not as ephemeral spectacle but as an experimental mechanism within strategic public-space planning. Their four Australian pop-up park cases began by reallocating street space to pedestrians and later became permanent through combinations of community activism and local-government support. The iconic idea is “proof of concept”: temporary intervention allows planners, residents and businesses to experience spatial change directly before it is fixed. Methodologically, the study combines planning documents, interviews, media records and mapping of land use, movement and surrounding urban form, then reconstructs each project’s longitudinal trajectory from trial to permanence. Its theoretical contribution is to reposition temporariness as a performative mode of deliberation capable of producing embodied evidence, negotiation and institutional confidence. The paper bridges tactical urbanism, planning theory and public-space design by showing how reversible, low-cost interventions can function as governance devices that test interests, resolve conflicts and incrementally stabilise durable urban transformations.