Exploring the Complex Spatial Characteristics of Large Railway Stations: A Multidimensional Assessment of Spatial Compactness

Railway stations are key nodes connecting urban space with regional transport networks. In the context of compact city development and station–city integration, developing railway stations as compact, three-dimensional composite spaces is an important means of improving land-use efficiency and coordinating transport and urban functions. To quantitatively evaluate the compactness of three-dimensional composite space and the level of station–city coordination, this study develops an evaluation framework comprising 26 indicators across three dimensions: functional configuration, spatial organization, and efficiency and accessibility. Following indicator selection and data standardization, the entropy weight method is used to derive objective weights, which are incorporated into a TOPSIS model. Eighteen representative railway stations are evaluated and ranked using the model, while their development levels are classified using the rank-sum ratio (RSR) method. The results show that Kyoto Station, Osaka Station, Shanghai Hongqiao Railway Station, and Berlin Central Station exhibit relatively high spatial compactness in their three-dimensional composite spaces, whereas Milan Central Station and London King’s Cross Station show comparatively weaker levels. The five clusters identified through K-means clustering were interpreted in light of the evaluation results and spatial characteristics, and subsequently consolidated into four spatial development types: High-Compactness Urban Comprehensive Type, High-Compactness Underground Station Type, Moderate-Compactness Transport-Dominant Type, Low-Compactness Regionally Oriented Type. The study identifies key spatial factors influencing the three-dimensional integrated development of railway stations. The findings provide a quantitative basis for the intensive space use, station–city coordination strategies, and architectural design optimization.