Development and analysis of the boundary permeability index of Urban Greenspaces: a case study in Edinburgh

Urban greenspaces play a vital role in enhancing the well-being and health of urban residents by offering fresh air, recreational opportunities, and emergency shelters. However, citizens' equitable access to these benefits may be impeded by boundary barriers, which could be distributed unevenly across the city, giving rise to the issue of unequal greenspace barriers experienced by specific areas. This study aims to introduce a novel approach to assess urban greenspace boundary barriers using visual interpretation of Google Street View maps. The greenspace boundaries are categorized into five categories: Closed, Open, Door Restricted, Barrier Restricted, and Unknown. Based on this classification, the study proposes the Boundary Permeability Index (BPI) for each greenspace type and examines the distribution of the index within Edinburgh. Additionally, the Scottish Index of Multiple Deprivation (SIMD) data is utilized to construct Ordinary Least Squares (OLS) and Geographically Weighted Regression (GWR) models was utilized for analyzing the spatial distribution of BPI values across regions with diverse socio-economic characteristics, with the primary aim of identifying potential social inequalities. The findings reveal that regions such as North Central and East Edinburgh exhibit high greenspace BPI values, exceeding 0.9. Five variables, namely HLTHALCSR, GACCPETROL, GACCDTPOST, GACCRANK, and HOUSERANK, exhibited a significant positive relationship with Boundary Permeability Index (BPI) values in the OLS model. The GWR model (R2 = 0.217, AICc = -13.935) demonstrated superior performance compared to the OLS model (R2 = 0.116, AICc = -1.158) in elucidating the association between greenspace BPI values and the explanatory variables. Furthermore, the study findings reveal that this positive effect is more pronounced in areas characterized by higher levels of deprivation, suggesting that greenspace boundaries may be more restrictive in deprived regions than in affluent ones. The proposed methodology for quantifying the urban greenspace boundary permeability index offers a valuable framework that can be applied to other cities and serves as a foundational reference for future investigations into urban greenspace accessibility and boundary barriers