Budget Optimization for a Postearthquake Regional Road Network Considering Connectivity Reliability

The connectivity between earthquake-affected areas and unaffected regions directly affects rescue efficiency and resource allocation speed following seismic events. Therefore, reinforcing critical road units in road networks before disasters is essential to ensure postdisaster connectivity. This study models road networks as topological graphs, assigning binary states (connected or interrupted) to road units for simulating postseismic damage scenarios. The integration of the virtual edge method with Monte Carlo simulation facilitates the quantification of connectivity reliability between unaffected and disaster-affected zones, thereby enabling the identification of critical locations exhibiting low connectivity reliability. Subsequently, a budget-optimized model is formulated. Through the process of sensitivity analysis, a critical subset of road units is identified, and an effective algorithm is developed to solve the model. This approach results in a cost-optimized strategy that minimizes total retrofit costs for road units while ensuring the minimum connectivity reliability threshold is maintained in disaster-affected zones. The technical viability of the proposed methodology is validated by case studies.