Planning for the urban future: two-level spatial analysis to discover 15-Minute City potential in urban area and expansion in Tallinn, Estonia

Tallinn, Estonia's capital, has seen substantial urbanisation-related changes in recent decades due to global and geopolitical shifts following the Soviet Union's collapse. This surge in population led to increased demand for urban expansion and shaped a scattering residential settlements around Tallinn. This study centres on Tallinn's alignment with the 15-Minute City concept, focusing on accessibility, efficiency, and sustainability. We employed two-level spatial analysis. On the first level, we evaluated Tallinn's alignment with 15-Minute City criteria related to population, transportation, and essential services. On the second level, we assessed suitable areas for urban expansion in Harju County, considering various environmental and spatio-functional factors. Results identified the most suitable areas for expansion in the northern and central parts of Harju County, about 35 km from Tallinn's centre, with higher population density and good infrastructure accessibility. To advance Tallinn's progress toward a 15-Minute City, urban planning should prioritise in areas with the highest suitability when expansion is considered necessary, to ensure equitable service distribution, and emphasise environmental sustainability.