A systematic maintenance process is essential to keeping railway systems safe and reliable. However, performing such maintenance is costly and often results in system disruption. There is a tradeoff between system safety and budgetary constraints; understanding the condition of the track infrastructure is essential to find the balance between needs and costs for decisions about when to perform maintenance. In this study, the track quality index (TQI), which is commonly used to evaluate the status of tracks and to decide maintenance interventions, is reviewed, including 12 TQIs for superstructure and six for substructure. A literature review indicates that TQIs for sleepers and subgrade have not yet been developed. The differences between TQIs are compared using a set of hypothetical raw data. Their capabilities for identifying track irregularities are also investigated based on the EN 13848 regulations. To classify TQI characteristics in a systematic way, this study proposes four concepts: accuracy, sensitivity, data required, and specificity. Accuracy indicates a TQI’s capability of detecting defects; sensitivity indicates how TQIs change according to variations in the defects; specificity relates to the amount of parameters considered, and the ability to pinpoint root causes or global consequences of defects. The results suggest a tradeoff between the four concepts, where high sensitivity can increase the ability to detect the smallest defects but may be affected by bias; more parameters considered may indicate low accuracy when detecting a single type of defect. Therefore, this study suggests railway regulators use multiple TQIs with complementary characteristics for classifying track status.

系统维护过程对于保持铁路系统安全可靠至关重要。但是，执行此类维护的成本很高，并且通常会导致系统中断。在系统安全和预算约束之间需要权衡；了解轨道基础设施的状况对于找到需求和成本之间的平衡，以决定何时进行维护至关重要。在这项研究中，对通常用于评估轨道状态和决定维护措施的轨道质量指数（TQI）进行了回顾，其中包括用于上部结构的12个TQI和用于子结构的6个TQI。文献综述表明，尚未开发出用于枕木和路基的TQI。使用一组假设的原始数据比较TQI之间的差异。还根据EN 13848规定研究了它们识别轨道不规则的能力。为了以系统的方式对TQI特征进行分类，本研究提出了四个概念：准确性，敏感性，所需数据和特异性。精度表示TQI检测缺陷的能力；灵敏度指示TQI如何根据缺陷的变化而变化；特异性与所考虑的参数数量以及查明缺陷的根本原因或整体后果的能力有关。结果表明，需要在这四个概念之间进行权衡，其中高灵敏度可以提高检测最小缺陷的能力，但可能会受到偏差的影响。检测单一类型的缺陷时，考虑的更多参数可能表明准确性较低。因此，