Safety assessment of COTS RTOS based computer platform applied in train control system

Commercial off-the-shelf (COTS) based computer platform is deemed as a promising candidate for application in safety critical systems. The foresight of this choice will make system transplant and software reuse efficient, and help vendors conquer the stress of development cycle and cost. Actually, it is nothing new in aviation and aerospace. However, no literature is proposed to argue the safety issues on a viewpoint of system attribute in train control system but only concentrates the behavior of COTS products themselves. System theory is the key to construct a solid and coherent safety assurance framework for the interaction between COTS sector and other parts, which will explicitly demonstrate the concept of safety on a system level. In this paper, a picture of propagation from bottom functional failures and performance degradation of COTS resource to the top-level hazardous events is depicted to show how safety analysis and risk evaluation of train control system is affected. Additionally, several experiments are carried out to support the argument.