Tolerable Hazard Rate Allocation for Urban Rail Automatic Train Control System

To improve the reliability and safety of urban rail Automatic Train Control System, it is Query ID="Q1" Text="As Per Springer style, both city and country names must be present in the affiliations. Accordingly, we have inserted the country name in the affiliation 2. Please check and confirm if the inserted country name is correct. If not, please provide us with the correct country name." necessary to allocate the tolerable hazard rate (THR) of the Automatic Train Control (ATC) system to each subsystems and components during the design and implement of specific urban rail transit signaling system. In the beginning, this research analyzes the architecture of ATC system, as well as safety functions and overall safety requirements for the urban rail transit signaling system. Next the specific requirements and principles of equal apportionment technique, safety impact-based apportionment technique and complexity-based apportionment technique are discussed. Combined with the ATC system architecture, safety logic model and specific engineering design parameters, theses three safety allocation methods are used to allocate the THR to each subsystems of ATC as the requirements. At last, the comparison of allocation for these techniques shows that the allocation method based on system complexity is the most suitable for the actual conditions of the project, which can meet the requirements of the Urban Rail Automatic Train Control System. Therefore, this research is proved to be meaningful to improve the reliability and safety of urban rail transit to some extent.