Design and Implementation of Real-Time Wearable Devices for a Safety-Critical Track Warning System

Trackside railway workers can benefit of intelligent systems for automatic track warning, that are able to safely (i) detect trains or rolling stock approaching the worksite, and (ii) notify their arrival to the workers. The usage of wearable mobile devices to monitor workers positions and notify trains arrivals requires to face serious challenges mainly in terms of service timeliness, safety, security and ergonomics (this last one to define notification signals to the workers that are always perceivable). This paper presents the design and the prototype of the Mobile Terminal (MT), a wearable, real time, wireless, safety-critical device which exploits information received from track monitoring devices to inform a worker about trains or rolling stock approaching the worksite. The MT design concept is based on a hybrid architecture to favor the apportionment of different requirements, in terms of timing and security, to the different parts of the MT. Additionally, the MT includes novel solutions to interface with the worker, to realize an accurate localization service and to achieve safety-critical real-time communication.