15-Minute or X-Minute City - An application of accessibility analysis to the districts of Aberdeen, UK

The 15-Minute City has received increasing attention in recent years in both urban planning practices and academic literature (Graells-Garrido et al., 2021). The forerunner towards such a city model was Carlos Moreno in 2016 in response to three main challenges for cities: (i) reducing car dependence to promote active mo- bility and reducing fossil fuel depend- ence of urban transport; (ii) boosting energy transition and decarbonization process in urban areas; (iii) improving the urban quality and liveability of citizens by offering a new mobility paradigm oriented also to support the reorganization of urban activities, places and paths. This new perspec- tive of looking at the city reachable in 15 minutes is based on concepts of equity and proximity that aim to reach all essential and everyday services through sustainable forms of mobility for all users by decreasing social inequalities (Buettner & Zucaro, 2024; Khavarian-Garmsir et al., 2023). The city is the place where quantities of activities coexist about each other, from the most every day and traditional to the most specialised and innovative. The accessibility to local activities requires the single parts of a city need to be 15-minute sized, thanks to a suitable pedestrian network connecting the different districts too, so to promote the use of public transport and the other forms of soft mobility. As some studies have pointed out, the idea may be ambitious, but feasible given that some cities have been planned to meet this requirement (Papas et al.,2023). In turn, the 15-Minute City is grounded in various planning practices that have followed one another over time and have defined the shape of urban fabrics, marking the identity character of plac- es (Gaglione et al., 2022; Bartzokas & Bakogiannis, 2022; Pellicelli et al., 2024). The 15-Minute City is reinterpreted in Ebenezer Howard’s Garden City, which proposed the creation of compact districts characterised by the presence of green areas and basic services. Later in Clarence Perry’s Neighbourhood Unity aimed to create residential units where the proximity of services and housing help establish a sense of belonging to a community. Still to follow with Walter Christaller’s theory of the central place, Jane Jacobs’ approaches to urban vitality, Harris and Ullman’s polycentric city; Torsten Hägerstrand’s geography of time that later evolved into chronourbanism or Calthorpe’s Transit Oriented Development (TOD) and finally Christopher Alexander and Jan Gehl’s human-scale urban design (Gower & Grodach, 2022; EIT, 2022). Although this “new” approach to looking at the city does not seem entirely new, it poses several research questions on how to rethink physical and functional organisation by combining the spatial and temporal dimensions. In recent years, the scientific community has produced a large number of articles aimed at investigating which urban characteristics need to be addressed in order to meet the requirements of the ±15-Minute City with aimed at measuring the levels of urban acces- sibility through multimodal forms of sustainable travel (walking, cycling or local public transport), (Mezoued et al.,2022).