Railway systems signalling and functional safety simulation and design

While autonomy is increasing in rail systems today, it is very important for safety to create functional safety designs that ensure the system's own safety and eliminate the negative situation in case of failures. In this study, within the scope of functional safety in rail system signaling, accident simulations are created for trains which are braking to stop in front of an obstacle. With the help of the document of the European Railways Agency, brake curves have been produced for the Metro and High Speed Trains. Then, a sample fault tree analysis has been created by selecting various failures that may occur before and after braking from the safety analysis document determined by the UNISIG consortium, and by adding emergency brake suggestions in case of failures. Then, simulations have been created by writing programs in Matlab software. The accident rates that may occur when failures occur randomly have been determined with the help of Monte Carlo Simulation, and the effect of the activation times of the emergency brakes on the probability of accident has been investigated. The obtained results were evaluated and discussed from various perspectives. As a result, the necessity of functional safety systems based on advanced technology has been emphasized and new suggestions have been made in order to completely remove the accidents.