# Improving the Resilience of High-Speed Rail Systems from a Configuration Perspective
## 2 Literature Review
### Driving Variables of HSR System Resilience Improvement
#### 2.1.1 HSR System Ontology-Related Variables  
HSR system ontology-related variables affect the vulnerability of an HSR system. [PERSON] (2014) indicated that the installment of a positive train control system can prevent collisions and derailments caused by excessive speed [33]. [PERSON] et al. (2019) examined the relationship between organizational characteristics of HSR operators and risks management [34]. [PERSON] (2015) identified several contributors to rail accidents, i.e., (i) rack, roadbed, and structures, (ii) signal and communications, (iii) miscellaneous, (iv) train operation-human factors, and (v) mechanical and electrical [35]. [PERSON] et al. (2020) highlighted organizational and institutional factors affecting HSR operation safety [6]. [PERSON] et al. (2019) emphasized the importance of a control structure model in safety management [8]. [PERSON] et al. (2020) pointed out three variables influencing the vulnerability of HSR project, i.e., capital, technology, and management [36]. [PERSON] et al. (2020) proved that chain vulnerabilities can affect chain resilience [37]. In accordance with previous studies, this study identified six HSR system ontology-related variables, i.e., technical  
Figure 1: System performance pre-disturbance, post-disturbance, and post-restoration (refer to [27]). system, quality control, equipment operation and maintenance, organization structure, organization efficiency, and system operation and maintenance. Technical system (TS) means the interaction and association of technical institutions, team resources, technical services, and other technical consortia. According to the statistical analysis of 80 railway accidents in the UK by [PERSON] and [PERSON] (2013), 44% of railway accidents are directly or indirectly caused by technical failures [38]. In addition, [PERSON] et al. (2020) confirmed that different technical standards affect the vulnerability of HSR system [36]. Quality control (QC) refers to the strict implementation of technical standards and operating standards in construction and operation management to ensure structural safety and engineering quality. Facing the same disaster damage, a high-quality HSR system is more stable and safe in the operation stage [36]. In addition, a poor HSR system may directly lead to accidents at the operation stage [39; 40]. One prominent example is the detachment of the Fukuoka-ken tunnel cement damaging the train. Equipment operation and maintenance (EM) is defined as the installation, replacement, or maintenance of related equipment or parts of the HSR system, as well as the handling of faulty equipment and other operations and maintenance work [41]. According to the Union Internationale des Chemins de fer (UIC), about 17% of 1785 railway accidents that occurred in Europe in 2017 were directly caused by internal causes within the railway system [42]. Organizational structure (OS) is the way by which organizational activities are divided, organized, and coordinated [43]. It involves hierarchy layers, horizontal integration level, centralization of authority, and communication patterns [44]. To increase efficiency and reduce operating costs, time-based manufacturing may optimize their organizational structure [45]. Due to the characteristics of high speed and high density, an effective organization structure is crucial for dispatching and commanding. Organizational efficiency (OE) means the extent to which an organization fulfills its objectives [46]. Efficiency losses will reduce an organization's resilience [24]. To ensure people's daily travel and safety under a specific organizational structure, high organizational efficiency, by reasonably distributing responsibility, power, and benefit, is critical. System operation and maintenance (SO) refers to a kind of operation and maintenance management for emergency command and rescue. [PERSON] and [PERSON] (2015) highlighted the improvement of resilience attributes of maintenance [25]. Adaptive maintenance in an HSR system can reduce operation risks.