Intercity transmission networks of Construction Cost Index fluctuations: structural characteristics, dynamic evolution, and forecasting utility

As a core tool for construction risk early warning and investment decision-making, the Construction Cost Index (CCI) has long delivered unsatisfactory forecasting performance under conventional single-city frameworks, and the structural sources of such bias remain under-explored from an intercity linkage perspective. This study integrates Granger causality tests and complex network analysis to construct an endogenous cross-city CCI transmission network without exogenously preset spatial weights, captures its dynamic evolution via rolling windows, and verifies the structure’s economic value through out-of-sample forecasting validation. Empirical results show that CCI fluctuations across Chinese cities are embedded in a directional, hierarchical transmission network with distinct functional division among core, hub and peripheral cities. The structure maintains overall medium-term stability while undergoing local phased adjustments under external shocks, and carries measurable incremental predictive value with spatially heterogeneous forecasting gains matching urban network positions. This study breaks through the traditional single-city static analytical paradigm of CCI research, providing empirical evidence and a structural perspective for optimizing forecasting systems and improving construction cost risk management.