In recent years, there has been an increasing interest in the adoption of drones for monitoring a variety of infrastructures. Infrastructure monitoring systems are widely adopted to detect faults before they can lead to severe failures. They can be found in a number of civil structures, including bridges and viaducts, and also in many other applications of smart-maintenance, prognostics, health and security monitoring. This paper explores the usage of drones in railways for early warning, situation assessment and decision support applications. It leverages already available technological and research achievements for drone-based surveillance. The aim of the study is to preliminarily evaluate drone capabilities in a railway monitoring framework including structural faults and security threat detection as well as investigation on the consequences of natural hazards and intentional attacks.