Railway Infrastructures E-Maintenance Systems: A Literature Review

This paper aims to identify and summarise available literature on railway infrastructure e-maintenance system as a report of the state of the art of research in railway infrastructure e-maintenance system by systematically classifying the published literatures in the period of 2000-2023. The author identify the aspects and elements which influence the railway infrastructure e-maintenance system as well as various approaches to optimize the railway infrastructure e-maintenance system. This paper identify the current research gaps in order to conduct the future prospect of the research. As results, it is observed that based on the study of the published literatures, the implementation of e-maintenance in railway infrastructure sector mostly focus on the use of the information and communication technology (ICT) itself and there is no proper integration between the managerial aspects (i.e. regulation, work breakdown structure, risk, and safety) with information and communication technology (ICT) to optimize the e-maintenance system.


Introduction
Transportation plays a role in economic growth, population growth, and social transformation in many countries [1][2].Trains are one of the transportation that plays an important role in the socio-economy of an area [3].According to [4], railway transportation is an alternative to land transportation that has an important role in the logistics supply chain.The railway transportation system is able to transport passengers and goods in large quantities so that it is more efficient when compared to other land transportation [5].Railway transportation is generally one of the safest forms of transportation, with the risk of accidents caused by railways being 7 times less than that of road transportation [6].In other words, railway transportation is more energy efficient, area, safer, and more environmentally friendly when compared to road transportation [7].In Indonesia, over a 10-year period from 2012 Based on data obtained from Central Bureau of Statistics, over a 10-year period from 2012 to 2022, the average annual growth of railway passengers and cargo is 10% and 11% respectively.In an effort to improve the level of service of railway transportation in Indonesia, the government of the Ministry of Transportation explained that it will carry out planning related to the addition of train capacity so that passenger capacity can increase by 40%.The increasing number of trains and the increasing intensity of the train flow can cause an increase in deteoriation in railway infrastructure, therefore it is important to carry out an adequate railway infrastructure maintenance system [8].It is also explained in [9] that during the operation and maintenance phase, the performance of buildings and facilities will decline as components and structural elements age.Today with the world's ever-evolving technological developments, increasing global competition, and environmental and safety aspects that need to be considered, the optimization of operational and 1324 (2024) 012045 IOP Publishing doi:10.1088/1755-1315/1324/1/012045 2 maintenance functions faces so many challenges [10] The railway infrastructure maintenance system itself is currently still facing several problems, including decision-making problems related to contracts, maintenance strategies, planning, and scheduling; technical problems related to implementation that are not optimal and not integrated, weak infrastructure monitoring and assessment systems, and the availability of qualified resources [11][12][13].And those problems of the maintenance system can be overcome by utilizing e-maintenance [14].E-maintenance is the concept of integrating information and communication technology (ICT) with maintenance strategies [15] Unlike conventional maintenance, e-maintenance allows for more efficient and transparent integration of information so as to realize collaborative maintenance where the implementation of this maintenance can be done remotely and immediately [16].With the various benefits that can be gained from implementing e-maintenance, this research intends to develop e-maintenance on railway infrastructure.

Research Aim and Scope
This research is the initial stage of a series of studies that will be carried out in the development of the railway infrastructure e-maintenance system in the future.This paper aims to identify and summarise available literature on railway infrastructure e-maintenance system.The scope of the research only focused on railway infrastructure maintenance system, the concept of e-maintenance, and e-maintenance implementation in railway infrastructure.Research related to rolling stock or railway vehicles lies outside the research scope.

Research Methodology and Results
A systematic research was conducted by searching for the following keywords in article titles: 'Railway Infrastructure Maintenance', 'Railway Maintenance System', 'Railway Infrastructure eMaintenance', and 'Railway Infrastructure Smart Maintenance'.The research scope was limited by only English literature research, review, report, and articles that published in the period of 2000-2023 and Scopus indexed.The resulting documents were filtered in a systematic methodology such as excluding irrelevant subject areas, removing duplication, reviewing the titles and abstracts, and thorough reading, the detail processes can be seen in "Fig.1".A further comprehensive screening was conducted through the full documents which yielded 40 articles.

Railway Infrastructure Maintenance System
Railway infrastructure performance indicators divided into managerial indicators and condition indicators [17].Managerial indicators include engineering aspects, organizational aspects, economic aspects, and health, safety, and environment (HSE) aspects.Meanwhile, condition indicators include the condition of railway infrastructure assets consisting of substructure, superstructure, railway yards, electrification, signalling, and information and communication technology (ICT).The achievement of railway infrastructure performance is still faced with various challenges.Based on [11] the problems of current railway infrastructure maintenance that might be occurred are things related to maintenance dimensioning, contract design, resources apects, project planning, maintenance schedules, and track usage.In addition, technological limitations, resource capabilities, accuracy of techniques used, suitability of quality applied, rail traffic management, and local weather & climate conditions are other issues in railway infrastructure maintenance strategies [12].Besides human factors and climatic influences, [18] added several other factors that affect railway infrastructure maintenance strategies, including technogenic factors such as the impact of the interaction between rolling stock on the track and its characteristics and the speed movement, and also natural factors such as flood waters, landslides, etc.
In overcoming the problems that exist in the railway infrastructure maintenance system, it is necessary to understand the taxonomy of maintenance strategies first.Taxonomy in the development of maintenance strategies is classified into 3 main attributes, including railway system structural characteristics, maintenance management decisions, and decision-making framework [19].Railway system structural characteristics are related to the configuration of existing infrastructure in the railway transport system, its component level and how defect mechanisms of the components.Then in atribtut maintenance management decisions include several things such as maintenance policy, maintenance operation (e.g.maintenance activities and resources), degree of maintenance, decision-making level (i.e.strategical, tactical, and operational), decision areas in maintenance planning, and decision areas in maintenance scheduling.And the last attribute, in the development of the decision-making framework is based on infrastructure degradation modeling, railway maintenance planning & schedule (RMP&S) objectives, RMP&S optimization constraints, and solution approaches.Railway infrastructure maintenance system optimation can be done in several ways.Firstly, an integration between reliability, availability, maintainability, and safety (RAMS) approach with life cycle cost analysis (LCCA) was recommended on railway infrastructure design and maintenance methods [20][21].Life cycle cost analysis (LCCA) provides design and maintenance method alternatives considering to costs and performances while reliability, availability, maintainability, and safety (RAMS) target can be achieved.Secondly, due to policy updates, organizational changes, and infrastructure & technology development, maintenance strategic planning was conducted based on the Plan-Do-Study-Act (PDSA) cycle approach [22].There are four steps in the link and effect model of maintenance strategic planning Plan-Do-Study-Act (PDSA) cycle based.The first step is 'break down of objectives', extracted from the organization's visions and missions and stakeholders' objectives which usually conflicting, then assembling them into a common framework.The second step is 'updating the measurement system and aligning of indicators', in response to organizational changes, new technologies, and changes in physical asset structure, the calculation of indicators can change into new and better way measurement.The third step is 'analysis of data for indicators, performance killers and drivers', the link and effect model complements thresholds with the underlying performance drivers and killers and providing a strating point for improvements.The last step of the link and effect model is 'identification of improvements, ranking and implementation', includes the evaluation of all process so that continuous improvement of the railway infrastructure asset management can be occurred.Next, risk-based approach can be applied in railway infrastructure maintenance system optimation [20], [23][24].Risk assessment is a key element of managing technical assets at all stages of their life cycle [23].Risk management cycle processes according to [25] are consists of 6 steps that are risk identification, risk analysis, risk evaluation, risk treatment, risk control, and risk monitoring.On railway infrastructure maintenance system, risk management is implemented in all decision making levels such as strategic, tactical, and operational [24].Risk factors were identified in each maintenance activities for different maintenance strategies and can be defined from financial, business, environmental, social, etc [20].Beside that, occupational health and safety (OHS) [26] and fire risk [23] should take into account.
Last, railway infrastructure maintenance system can be optimized by the usage of the development of technology.The usage of technology on maintenance framework called e-maintenance which was conducted could support its value chain by integrating the pertinent data, information, knowledge, and intelligence [27].The further review regarding e-maintenance will be discussed on the next subheading.

E-Maintenance Concept
E-maintenance is the set of maintenance processes that utilize e-technologies to enable proactive decisions in a particular organization which ensuring that the e-maintenance services are aligned with the needs and objectives during the whole product lifecycle [28], [29].The e-maintenance framework based on [27] was structured by five components, such as strategic vision to determine the scope, business process, organization, service and data architecture, and information technology (IT) infrastructure.E-maintenance provides potential improvements in maintenance types and strategies such as remote maintenance, collaborative maintenance, real-time maintenance, and predictive maintenance [16].The e-maintenance framework can be carried by business process modelling approach which utilizes the business process modelling notation (BPMN) and unified modelling language (UML) [28].
The BPMN consists of three elements, i.e. computerized maintenance management system (CMMS) module, condition-based maintenance (CBM) module, and e-maintenance process.These elements were integrated through business process modelling notation (BPMN) then the business process model was adjusted into one language program standard based on MIMOSA standard by using unified modelling language (UML).
These days e-maintenance still faces some potential challenges.The first challenge is regarding to data management [16], [30].The data collection can be objective and subjective, hence the quality of data may be not valid.This is due to the acquisition of data that can be objective and subjective so that the quality of the data obtained is invalid, the flow of information is fast so that stakeholders need to keep up with the pace, large amounts of data from heterogeneous sources, data transfer to all interconnected systems, and maintenance data that is still raw with different formats.Thus, key performance indicators (KPI) regarding data collection needs to be determined [30], automation in data collection [16], [30], conduct an information system that appropriate for internal and external organizations [27], [30], and standardization in data unification [16], [28], [30].
The next challenge in e-maintenance is related to the readiness of its implementation.The organization may not have the proper competencies in their man resources to adapt and implement e-maintenance because of its digital transformation [27], [31], [32], therefore the training of the man resources need to be carried out [33][34].The organization itself is needed to be changed conform the digitalization [32], [34].To enable the digitization of maintenance, the government or the policy makers need to update the regulations, because certain regulations may obstruct the progress [34].The availability of financial resources play an important role in the implementation of e-maintenance.Limited operating expenses and the uncertainty regarding the effects on the overall cost of new equipment and technology procurement oftentimes hinder the organization in carrying out the e-maintenance [34].
The effectiveness and the efficiency of e-maintenance system can be improved by developing the emaintenance framework considering in some aspects below.
• Regulation: regulation is a fundamental instrument to support the e-maintenance system.Regulation has a significant impact in the implementation of e-maintenance [35][36].
Regulations can determine the strategy decisions because the needs of regulation compliance [34].• Strategy: maintenance digitization can change maintenance working practices [34] which will influence the maintenance strategy and guidelines based on the appropriate type to be carried out, such as preventive maintenance or time based maintenance, predictive maintenance or condition based maintenance, and corrective maintenance or failure based maintenance.In forming the maintenance strategies needs to be based on the work breakdown structure (WBS) [35][36][37][38], due to being able to improve accuracy both when planning schedules and costs as well as when identifying risks that may occur.Likewise work breakdown structure (WBS) which decomposes the e-maintenance business processes into activities can help the organization to develop their units [39].• Organization: the e-maintenance organization must support the business process integration [39].The organization needs to develop their organizational units because the new roles, a new way of thinking, new culture, and new working methods will be required [29], [34].Defining organization consists in assigning activities and their related procedures to the organization units that will perform these activities on a specific site [39].Due to the digitalization, manpower also ought to be trained properly to perform e-maintenance.Education and training are just as important component as all the other e-maintenance components [29].• Culture: based on empirically performed research, to achieve a faster and more efficient emaintenance transformation there should be a higher attention to organizational culture and leadership [40].Organizational cultures that ought to be ensured in e-maintenance implementation are safety & health awareness [11], [26], [34], [38] and risk awareness [34].

E-Maintenance Implementation Trends in Railway Infrastructure
In Indonesia, railway infrastructure maintenance still not implemented the e-maintenance concept.The use of ICT in railway infrastructure maintenance systems is still limited as a communication tool and maintenance information system database, but not well integrated.According to [13], railway infrastructure maintenance management in Indonesia has several problems that need to be studied further, including problems of finance management, problems of structure organization, and problems of asset management.In the financial management aspect, contracts are one of the problems.In Indonesia, operation and maintenance is monopolized by one company so that there is no competition which causes output that is not optimal and less innovation.Furthermore, the contract system is still carried out annually meanwhile according to the simulation that had been conducted by [43] the optimal contract system for operation and maintenance it is carried out every 5 years.Then from the organizational structure aspect, including companies that carry out operations and maintenance that are closed or not transparent, policy makers are the owners of the assets themselves which can be at risk of weak control, and there is no integration between regulations related to safety and economy.Last in the asset management aspect, the problems that occur include the implementation of inspections which are still not optimal and not integrated, asset planning pay less attention to existing assets but focuses on development, the infrastructure monitoring and assessment system is still poor and inadequate, and the maintenance strategy is only carried out using time based maintenance (TBM) and failure based maintenance (FBM).The implementation of railway infrastructure e-maintenance in Japan according to [44] is composed of 4 key elements which include achieving condition based maintenance (CBM), introduction of asset management, maintenance work support by artificial intellegence (AI), and integrated database.By changing time based maintenance (TBM) to condition based maintenance (CBM) possibly makes the maintenance prioritization be done more easily and carried out swiftly and in a timely manner [45].
Hence with the integration between condition based maintenance (CBM) and information and communication technology (ICT) form a platform that accurately perceiving deterioration and making decisions with the optimal timing and method.In order to implement railway infrastructure emaintenance, it is necessary to analyze the main capabilities and take a stand on issues surrounding them [34].
In several countries such as Italy, UK, Spain, and China, building information modeling (BIM) is implemented in railway infrastructure maintenance digital transformation [46][47][48][49][50][51].Its implementation can improve the railway infrastructure maintenance planning with time saving, cost optimization [46], [47][48][49][50][51][52], and provide the internal requirement in terms of the safety of the users [52].Building information modeling (BIM) facilitates all stakeholders, so they can keep the maintenance project scope in review if there is any changes [50].The time and cost effectiveness in railway infrastructure emaintenance processes also can be improved by using radio frequency identification (RFID) which has been implemented in China [53].With the wide use of radio frequency identification (RFID) technology in railway helps automatic identification of objects using radio waves which the data is available in real time for analysis and visualization.Objects automatic identification can also be done by using sensor as an option [34].Collection information digitally should be considered in railway infrastructure emaintenance to reduce errors if it is carried out manually.Geographical information systems (GIS) are also used in efforts of Turkey and China to digitize maintenance on railway infrastructure [54][55].GIS utilization can provide geographical perspective in maintaining railway infrastructure thus can allocate the resources wisely [55] & actualize the cost optimization [56].Geographical information systems (GIS) can also be integrated with building information modeling (BIM) which improves the system's scientific decision-making level in railway infrastructure maintenance [51].Building information modeling (BIM) provides the digital virtualization for various infrastructures through precise geometric while geographical information systems (GIS) can support in visualizing large-scale geographic area.

Summary of Key Findings
The systematic literature review highlighted a number of key findings summarised below: • In implementing the maintenance system on the railway infrastructure, there are 2 performance indicators that need to be fulfilled including managerial indicators and asset condition indicators.Managerial indicators consist of technical aspects, organizational aspects, economic aspects, and health, safety, and environment (HSE) aspects.Meanwhile, condition indicators cover the condition of railway infrastructure assets consisting of substructure, superstructure, railway yards, electrification, signaling, and telecommunication.• Railway infrastructure maintenance can be optimized by several ways that are integration between reliability, availability, maintainability, safety (RAMS) approach with life cycle cost analysis (LCCA), plan-do-study-act (PDSA) approach, risk-based approach, and the digitalization maintenance or e-maintenance.• Some aspects that ought to be considered in e-maintenance framework are regulation, maintenance strategy, guidelines, work breakdown structure (WBS), organization development, organizational culture & leadership, safety & health awareness, risk awareness, and the utilization of e-technologies.• Railway infrastructure maintenance that lately had been developed already use some information and communication technology (ICT) such as integrated database, building information modeling (BIM), geographical information systems (GIS), radio frequency identification (RFID), and sensors.The maintenance strategy itself is also focus on transitioning from time based maintenance to condition based maintenance.However, railway infrastructure e-maintenance that has developed today still has gaps from several aspects that need to be fulfilled both in railway infrastructure maintenance and the e-maintenance concept itself.
Railway infrastructure e-maintenance currently does not consider work breakdown structure (WBS), risk, and safety in the development of e-maintenance strategy.Moreover, the maintenance system carried out is still not integrated between one infrastructure and other railway infrastructure, such as railways, stations, signaling, etc.

Conclusions and Future Research
The aim of this research is to report the state of the art of research in railway infrastructure e-maintenance by systematically classifying the published literature, outlining research gaps and guiding future research.e-maintenance that had been developed on railway infrastructure been successfully implemented.But despite the limited research, it emerges that the e-maintenance itself has high potential to be improved due to the gaps between the current railway infrastructure e-maintenance to the ideal state.The findings outline in this research is the first step to provide direction to develop the railway infrastructure e-maintenance system.The next research will compose conceptual framework by identify the detail of significant factors of railway e-maintenance system based on the findings of current systematic literature review.