# A Maturity Model Proposal for Industrial Maintenance and Its Application to the Railway Sector
## 3 Results of Domains and Maintenance Strategies Analysis
### Domains in Prescriptive Maintenance  
Both RQ1 and RQ2 are oriented towards prescriptive maintenance. The search performed contained these two terms: \"prescriptive\" and \"maintenance\". Therefore, it can be stated that all the domains extracted from the selected documents can be found in the prescriptive maintenance strategy. The identified 18 domains have been classified into three defined areas: asset-oriented domains, asset status-oriented domains and maintenance-oriented domains. Figure 3 shows all the domains identified, and relevant references are also provided in each domain to those articles where more emphasis has been placed on the domain. ASSET: The first area was considered to include all the domains that refer to the definition of the asset itself. This definition should include not only basic information on the manufacturing and installation of the asset, but also an analysis of its criticality. The risk management of the asset can then be evaluated by the level of safety required. Criticality can also be conditioned by the availability of the asset. The implications of the asset being out of service should be evaluated. These two points of view emerge in the reliability domain. To do this, it is necessary to consider the implications of an asset failing and/or becoming inoperative, defining failure modes. All the information analyzed for asset management was used as a basis for the analysis and management of the next two areas. STATUS: This second area was considered for the domains describing the management of the health condition of assets. To guarantee the required level of availability of a given asset, its failure modes and the associated criteria to evaluate its current condition (e.g., by means of KPIs--Key Performance Indicators) must be defined. Once all failure modes and KPIs are identified, it is necessary to identify and define how the associated measurements to obtain such KPIs will be performed. In this way, discrete inspections of the asset were performed to evaluate its status. Depending on the criticality of the asset, preventive activities may not be sufficient. Therefore, it is necessary to consider monitoring systems to evaluate performance in a more continuous way. There are also cases where monitoring systems need to be accompanied  
Figure 3: Prescriptive maintenance domains. by diagnostic systems. If the level of criticality is even higher, it would also enter the prognostic domain. In this way, we could anticipate a warning state in the asset. MAINTENANCE: In this area there are domains linked to the maintenance and life cycle cost of the asset. Depending on the criticality of the asset, it can be necessary to adopt more advanced maintenance strategies and therefore address more complex domains. In all assets, regardless of the criticality, efficient management of the resources (personal, material, spatial and temporal) associated with operations and maintenance activities must be performed. Depending on the OPEX and criticality, domains such as decision support systems should be addressed together with decision and optimization models, thus studying the maintainability of the asset. Apart from the three areas mentioned above, there was an additional domain identified in the analysis: maturity levels. Several research papers refer to maturity levels in maintenance. Using different terms, they analyze the evolution through different maintenance strategies. Several papers analyze in more detail case studies of the analytical maturity model levels proposed by [PERSON] [17]. However, there is no clear guidance on the assessment of the maturity level, not only for the adoption of prescriptive maintenance [3; 32] but also for the rest of the strategies. It would be necessary to define the available technologies to assess the maturity level of the strategy that can be acquired [15]. The relationships and classifications described are those identified in the literature.