Fail-Safe Signalization Design for a Railway Yard: A Level Crossing Case

Level crossings (grade crossings or railroad crossings) are one of the most crucial parts of the railway lines as two different types of transportation intersect at these points. Human failures including ignorance of warning signs, device troubles or carelessness can easily result in accidents especially at such cross-sections. In order to decrease the possibility of accidents on level crossings, several standards have been developed. In accordance with these standards, formal methods are required to be used specially in the development of interlocking systems that control safe operation of such crossings. In this study, a railway yard with a level crossing is modeled by Automation Petri Nets in order to design a failsafe signalization system. A SCADA testbed is also developed to test several possible failure situations. The methods proposed in the design are expected to be used as part of an interlocking system in a railway station in Turkey.