Inter-regional research and development (R however, their distinct types and underlying mechanisms remain underexplored. Grounded in the “buzz-and-pipeline” theory, this study distinguishes between inter-regional collaborative R&D and inter-regional intra-organizational R&D networks and examines their impact on regional technological innovation in China’s railway equipment industry from 2001 to 2020. Employing a fixed-effects panel model, the findings indicate that both networks significantly enhance regional innovation by facilitating external knowledge spillovers. The innovation-promoting effect amplifies in regions with advanced digital technology and higher technological complexity. Crucially, regional gatekeepers serve as bridges and filters, enabling an inverted U-shaped relationship between the inflow of complementary external knowledge and local innovation. The heterogeneity analysis reveals that industrially developed and technologically specialized regions reinforce their technical advantages through these networks. This study refines the “pipeline” metaphor in innovation geography and provides a nuanced framework for designing region-specific innovation policies.
Zhu et al. (2026) studied this question.