A nested-block scalable framework for efficient and equitable urban infrastructure management

Global cities face mounting challenges in sustaining vast, interdependent infrastructure networks under fiscal and environmental pressures. Conventional optimization methods fail under the dimensional explosion of multi-year maintenance and renewal planning for hundreds of thousands to millions of assets. We present a nested-block optimization framework that decomposes city-wide networks into coordinated sub-blocks, transforming an intractable decision space into a solvable, parallelizable structure while preserving budgetary and temporal constraints. At million-asset scale, the framework achieves rapid convergence and fully feasible plans, far surpassing existing methods in efficiency and scalability. Its architecture unifies diverse assets including roads and pipelines, extends to energy or transit systems, and enables cross-asset, cross-scenario coordination through clustering by district, jurisdiction, or asset class. The framework provides a systematic tool for identifying key evolutionary patterns, evaluating investment pathways, and anticipating system transition conditions, while embedding equity objectives alongside efficiency. These results offer a scientific perspective on urban evolution and practical pathways toward more coordinated, just, and sustainable infrastructure management.