From heuristics to data: A parcel-level representation of site planning layouts from multimodal urban evidence

Site-planning layouts are difficult to compare computationally because many planning-relevant relationships are understood through professional judgement, heuristic rules, and regulatory practice rather than directly measurable variables. This study develops the Site Planning Layout Indicators (SPLI), a parcel-level framework that translates selected site-planning concepts and multimodal urban evidence into structured spatial indicators. SPLI links building-level morphology and functional hierarchy with parcel-level spatial organization, functional diversity, accessibility conditions, and land-use intensity. A reproducible workflow harmonizes statutory land use, parcel and building geometry, points of interest, street networks, and building-function information; supplements incomplete building attributes through relational graph-based inference; and distinguishes observed, derived, inferred, and interpreted fields while retaining their provenance and processing status. The framework is applied across statutory land-use categories and planning subzones in Queenstown, Singapore. An evidence-first classification procedure, threshold perturbation tests, implementation in a second planning area, and independent professional blind coding are used to examine the reproducibility and interpretive limits of the spatial-organization rules. Comparative analyses identify contextual differences in several SPLI fields, most clearly in accessibility and development intensity. SPLI provides a traceable operational basis for storing, comparing, and revising selected products of planning reasoning without treating professional judgement as universal ground truth.