Visualization and spatial analysis of socio-environmental externalities of urban underground space use: Part 1 positive externalities

Abstract

Socio-environmental externality is one of the distinctive identities of urban underground space (UUS) use and a decisive factor in the decision-making process of UUS planning projects. A growing number of attempts have been made to address the quantification challenge in monetary terms, but failed to articulate the spatial impacts of UUS uses, i.e., the distributional and quantitative extent to which UUS use will facilitate urban sustainability of a specific location, thus incapable of adequately promoting and legitimating UUS planning agendas. The gap can be filled by the geographically referenced visualization and spatial analysis, which require different datasets and approaches for positive and negative externalities of UUS uses. Accordingly, this study will be presented in two parts: Part 1 focuses on how UUS use benefits urban development; Part 2 pays particular attention to the potential threats posed by UUS use to urban sustainability. This part 1 paper builds on the service replacement cost method (SRCM) framework, under which the visualization process of positive socio-environmental externalities requires multi-sourced spatial data such as land use data, UUS planning data, population data, comprehensive transportation data and socio-economic data. Valuation results of the case study showed that the aggregated value of the socio-environmental benefits amounted to approximately 3.7% of the local GDP in 2018, with the most prominent contributions sourced from underground rail transit infrastructures and followed by the UUS uses beneath alienated land parcels. The spatial analysis rationalized the UUS planning of the case study area by demonstrating that the distribution of positive socio-environmental externalities derived from UUS uses was consistent with the planning visions of boosting and revitalizing local development, while most planned UUS projects yielded much greater external benefits than estimated construction costs.