Analysis and Application of Fully Automatic Operation System RAM Indicators in Urban Rail Transit

Objective Systematic correlation analysis between line operation indicators and RAM (reliability, availability, maintainability) indicators of each core equipment system in the FAO (fully automatic operation) system is insufficient. In view of this, it is necessary to develop an analytical framework that progressively maps FAO line operation indicators down to component-level RAM indicators.

Method Firstly, starting from the operation indicators of the FAO system, the intrinsic relationships between line operation indicators and product RAM indicators are analyzed, and a hierarchical RAM indicator analysis framework is constructed with a mapping chain of FAO system → core systems → subsystems → units → components. Secondly, the line operation indicators are clearly classified into two main categories, i.e. overall line service performance indicators and reliability indicators of single-system. Thirdly, taking Qingdao Metro Line 6 as the research object, the operation indicators are converted into allowable annual fault event counts based on line operation data. With reference to the fault proportion data, key operation indicators, including train service reliability, failure rate of train withdrawing from mainline operation, failure rate of train exiting FAO mode, and train wake-up success rate, are decomposed into specialized core systems such as train control, rolling stock, and platform screen doors. On this basis, reliability models for each core equipment system are established, RAM indicator is allocated using the comprehensive factor method, and FTA (fault tree analysis) is adopted to analyze and verify the overall FAO operation indicators. Finally, the rationality of the established indicator system is validated by comparing the allocated RAM indicators with the FTA analysis results.

Result & Conclusion  The results show that the MTBF (mean time between failures) indicators for each core system, obtained through the allocation of operation indicators, can satisfy the top event frequency requirements calculated via the FTA method. The decomposition and mapping from line operation indicators to equipment-system RAM indicators are achieved, and the consistency verification between operation indicators and equipment-system indicators is completed.