Exploring the 15-Minute City concept for the urban outskirts: a systematic literature review.

The 15-Minute City concept has gained a lot of attention in research and planning, aiming to increase access to essential services by foot and bicycle and create more attractive and vibrant neighbourhoods. Most research has focused on exploring the concept in central urban areas, where in many European cities essential services are already within a 15-min walk or cycle. This paper presents a systematic literature review that syntheses existing knowledge on the 15-min city topic, identifies literature gaps and describes missing elements or "the key enablers" that allow the concept to expand beyond urban cores, into peripheral areas where car dependence is typically high. Based on our systematic literature review examining 87 papers, there are three well-established spatial elements-density, diversity, and design-that are central to achieve proximity. However, we also identify other three critical but underexplored elements: individual's characteristics and needs, the role of digitalisation, and adapted governance and business models. These gaps limit the applicability of the 15mC across all contexts, particularly in urban outskirts. Our findings aim to inform planners and policymakers on the elements that need to be addressed for proximity-based planning to be effective across diverse urban contexts. Supplementary Information: The online version contains supplementary material available at 10.1186/s12544-025-00743-8.