Beyond Proximity: An LBS-Based Diagnosis of Planned–Used Life-Circle Mismatch in Lanzhou, China

Proximity-based planning provides a normative framework for organising everyday services, but local accessibility does not necessarily correspond to the spatial extent of observed destination use. Building on the distinction between normative proximity and grid-level aggregated revealed activity space, this study develops an LBS-based diagnostic framework for planned–used life-circle mismatch. Anonymised non-home, non-work home-grid–destination-grid links observed at least four times in aggregate during the month were analysed for 995 residential grids of 500 m × 500 m in Lanzhou, China. The framework evaluates five dimensions: boundary coverage, activity-space scale, centroid displacement, directional morphology, and destination environments, and translates them into four planning-diagnostic types. The results reveal widespread divergence between planned proximity and revealed use. On average, 82.0% of aggregated recurrent visit weight lies outside the corresponding 15 min walking boundary, while the median distance between residential and activity centroids is approximately 4.18 km. The outside-dominant pattern remains evident when the analysis is restricted to destinations located in selected basic-service-dominant POI environments. Greater local POI supply is generally associated with lower outside-boundary reliance, whereas bridge distance is more clearly associated with centroid displacement than with outside-boundary share. The explanatory models have modest fit and identify grid-level associations rather than causal behavioural mechanisms. These findings support treating the 15 min boundary as a normative benchmark for local service provision rather than a presumed container of residents’ daily activities. Planning evaluation should therefore combine accessibility standards with behavioural evidence and differentiated diagnosis. The LBS data do not identify trip purpose, travel mode, socioeconomic characteristics, service quality, or individual necessity, and the results should be interpreted as grid-level diagnostic associations.