Evaluation and Analysis of the Spatial Performance and Spatial Legibility of Wind–Rain Bridges in Hunan Under the Influence of Urbanization

Wind–Rain Bridge architecture is an important type of ancient bridge architecture. To reveal the factors contributing to the decline in the spatial performance of Wind-Rain Bridges in Hunan under the influence of urbanization and to assess their spatial legibility across different urbanization gradients, this study addresses the limitations of traditional research, which has largely relied on static observations and lacked quantitative analysis. The findings provide a scientific basis for the refined conservation and adaptive revitalization of traditional architecture. This study examines 535 Wind–Rain Bridges in Hunan. Using Space Syntax, core indicators such as Integration and Choice were quantitatively calculated for both Wind–Rain Bridges and modern bridges. A controlled variable experiment was further employed to analyze the disturbance effects of modern road networks. In addition, an XGBoost multi-classification model was constructed to assess spatial legibility levels and identify key spatial-topological predictors. The results indicate that the decline in the spatial performance of Wind–Rain Bridges in Hunan is not linearly correlated with urbanization. Urban-type Wind–Rain Bridges are most significantly affected by the replacement effect of modern road networks, whereas Semi-Village-type Wind–Rain Bridges exhibit the strongest resilience. Among the variables included in this study, Integration and Mean Depth are the strongest predictors of spatial legibility. This study establishes an analytical framework of “type classification–factor identification–differentiated strategy formulation” and confirms that the primary driver of the spatial performance decline of Wind–Rain Bridges in Hunan is the fragmentation of traditional pedestrian road networks caused by modern transportation systems under urbanization, rather than the aging of the bridge structures themselves.