This paper proposes a novel approach for composite risk management of rail operations incorporating operational risk computed by the rail industry and cyber security risk introduced due to Positive Train Control (PTC). The suggested risk model focuses on a given train location to estimate likelihood of the PTC system failing by considering environmental risk factors (precipitation, vegetation, obstacles) and the inherent vulnerability of the radio frequency yielding a measure of system impact. For the same location, the risk model considers safety related attributes such as train speed, track curvature, freight type, etc. offering an estimate of operational consequence if there were an accident due to the failure of PTC. It is this intersection of impact / consequence that separates the proposed model from existing risk calculations of impact / likelihood. This is accomplished by distinguishing the likelihood of a safety accident from the likelihood of a PTC system failure and incorporating them both. What results is an enhancement of both models; the operational risk model factors potential PTC failure in its risk assessment and gains awareness of possible requirements for operator intervention while the system risk model factors operational risk as its severity metric leading to possible requirements for automated risk mitigation by dynamic configuration change to the PTC radio.
