Development of an evacuation transport model for residents in need of assistance in evacuation during nuclear disasters

This study proposes a mathematical optimization model based on the Capacitated Vehicle Routing Problem to support the efficient transport of ”Residents in Need of Assistance in Evacuation” — such as the elderly and persons with disabilities — during nuclear disasters. The target area is Omaezaki City, Shizuoka Prefecture in Japan, where geographic open data — including census data, elevation data from the Geospatial Information Authority of Japan, and OpenStreetMap — were integrated to construct realistic road networks reflecting road accessibility during disasters. In particular, assuming tsunami-induced road flooding, we evaluated the impact of elevation-based road access restrictions on evacuation plans and identifying Residents in Need of Assistance in Evacuation in areas difficult to access. The model was optimized using both a Mixed-Integer Linear Programming approach and a genetic algorithm, and the results showed that Gurobi outperformed Genetic Algorithm in terms of both solution quality and computation time. The proposed model enables the quantitative identification of regions with limited accessibility based on the spatial distribution of home-based Residents in Need of Assistance in Evacuation and terrain characteristics, providing a practical decision support framework for local governments in disaster response planning and resource allocation.