Minimum cost deployment in earthquake early warning system for high-speed railways

High-speed trains, carrying high social and commercial value, travel at a speed over 250km/h, thus any damage to tracks would cause severe loss. Detecting events which can cause track faults is important to the safety of high-speed railway systems. Railways, crossing the vast area of plains and mountains, are vulnerable to earthquakes which can damage tracks with destructive forces. In recent years, earthquake early warning systems (EEW) attract great attention from public because losses of lives and properties can be greatly reduced with earthquake alarm it offers. However, conventional EEW system cannot offer satisfactory alarms for high-speed railway systems. Therefore, it is necessary to develop an EEW for high-speed railways (HR-EEW). One of the key issues in designing an HR-EEW system is how to offer timely alarms to trains under certain constrains, such as budget limitation and geological restriction. We propose HR-EEW systems based on wireless sensor networks (WSNs). In this paper, we take a close look at deploying wireless sensor nodes in HR-EEW systems. We target at solving the minimum cost deployment problem while guaranteeing that any earthquake in a seismic district can be timely reported by k sensors.We carefully investigate this problem and derive a critical condition for a deployment to satisfy a predefined performance requirement. Then, we present novel algorithms to solve the problem. Finally, we evaluate our methodology under real data and synthetic data.