In recent years, there has been an increasing interest in the adoption of emerging sensing technologies for instrumentation within a variety of structural systems. Structural health monitoring systems are widely adopted to monitor the behavior of structures during forced vibration testing or natural excitation (e.g. earthquakes, winds, live loading). They can be found in a number of civil structures, including bridges and viaducts, and also in applications of vehicle health monitoring. Moreover, since infrastructures can be damaged by human originated threats, the adoption of security measures is also essential. This paper presents a proposal of an early warning system based on Wireless Sensor Networks (WSN) for railway infrastructure monitoring. It exploits already available research results and tools for WSN management, integration and data fusion. The aim is to hedge detection capabilities in a complete framework for structural failures as well as security threats, including both natural hazards and intentional attacks.