Digital Stress-Testing of Urban Transport Resilience: Analyzing Systemic Isolation against Megathrust Tsunamis in Southern Java

Abstract

Sustainable urban mobility is defined not only by efficiency but by its resilience to catastrophic disruptions. The coastal district of Palabuhanratu, Indonesia, faces a critical vulnerability where its transportation network is bisected by major rivers, posing a severe risk during a potential Megathrust Tsunami (Mw 8.8). This study uses digital technologies for urban infrastructure analysis to evaluate transport system failure modes. Utilizing a quantitative approach based on Graph Theory and Anisotropic Least-Cost Distance (LCD) simulation, we stress-tested the road network under a specific "Bridge Failure Scenario" within a strict 22-minute evacuation window. The simulation reveals "Spatial Separation," where the collapse of the Cimandiri and Citarik bridges isolates 19 villages, creating a systemic disconnection from safe zones. The results quantify a critical failure in the transport and mobility system, showing a 23–38 minute time deficit for the isolated population. Furthermore, the analysis reveals extreme inequality in vehicular mobility, with the Gini Coefficient spiking to 0.995, indicating a near-total collapse of motorized access relative to pedestrian modes. The study concludes that the current urban infrastructure lacks the necessary redundancy. To support sustainable disaster management, we recommend integrating digital twin simulations into spatial planning and prioritizing decentralized tactical redundancy to strengthen coastal mobility systems' resilience.