Systematic literature review: financing system in railway transportation

. Trains are one of the least polluting modes of mass transportation. The creation of railway infrastructure aims to promote connection and mobility to spur economic growth. The purpose of this research is to provide an overview of railway funding around the world. The method is based on examining the literature on railway funding over the last 20 years. This research aims to provide an overview of railway funding issues and solutions and answers to challenges using research trends. This study's approach consists of three steps: bibliometric analysis with mapping through the keywords "rail" and "finance" from the Scopus account to get Scopus literature on railway financing, mapping using Vosviewer, and analyzing. The review included 506 articles published between 2008 and 2022 with the keywords "financing" or "finance" and "rail" "engineering" and "economic." The findings demonstrated that the high cost of infrastructure development and railway operations necessitated alternative creative financing to avoid taxing the state. Railway investment is significant, but revenue will be substantial in the future. Thus the PPP financing scheme is one of the alternative methods for acquisition, operating, and maintenance financing in railway transportation.


Introduction
The study and knowledge of railway financing are expanding.Specialists and economists are still searching for the best railway funding strategy to implement in each country.A financial management strategy that promotes economic and environmental advantages is the most suited [1].Yet, experience shows that train operating expenses are rising, increasing the national debt [2][3].
The intricacy of implementing railway financing is undoubtedly a challenge for academics and researchers in the subject of railway financing.It encourages the body of information about this topic to expand.A few scholars are still focused on developing research on this topic, particularly in Indonesia.This study aims to map knowledge about railway financing and look into future state-of-the-art and comparable research trends.
Examining the literature review might help you understand a study issue.A literature review is one method for learning about a research field [4].A literature review can be created using a variety of methodologies, one of which is scientometric analysis [5].Scholars believe that by integrating bibliometric analysis, scientific mapping, and further qualitative research, literature-based studies can be enlarged and more complete in the domains of study [6].
Based on previous research on railway financing, this study adds to the body of knowledge by: *Corresponding author: joniarliansyah@ft.unsri.ac.id

Methods
This study utilized a bibliometric analysis from the literature with the issue of railway funding followed by scientific mapping [7].Bibliometric analysis can also be used quantitatively, which improves the understanding of the material in a specific sector [8].Bibliometric analysis is more impartial and trustworthy than other literature review methods [9].The study will be more detailed by employing keywords to find the primary subjects in a limited area [10].Diagnosing the objective of the investigation will be feasible by applying a mapping.Furthermore, this study borrowed from various earlier studies on conducting a literature review [11][12][13].As a result, the steps in this study were bibliometric analysis via a literature search, scientific mapping, and a systematic follow-up review.

Bibliometric analysis
The techniques employed in this investigation include querying the Scopus account for keywords [14][15].Several scholars have also recommended Scopus as a source of literature [4,16].This study employs bibliometric analysis of rail financing-related literature from the 1970s to 2023, utilizing the Scopus account keywords "funding" or "finance" and "rail."The investigation was limited to the last 15 years (2008-2022), yielding 587 articles containing these keywords.This study's topic was restricted to "engineering" and "economics," delivering 506 papers.

Science mapping
The VOS-viewer was used in this study for several purposes, including: 1. Importing the literature source from Scopus to VOSviewer, 2. Computing the frequency and co-occurrence of keywords, 3. Extracting the citation relationship between articles, authors, publication sources, and institutions, and 4. Clustering and visualizing keywords, publication sources, and institutions based on co-occurrences (Fig. 1).

Systematic review
A systematic review is conducted to focus concisely on railway funding research that focuses on engineering and economics.This analysis aims to determine the needed State-of-the-Art (SOTA).

Results of bibliometric analysis
Bibliometric analysis was performed using a Scopus account with keywords "funding" or "finance" and "rail" and obtained 1,085 articles published between the 1970s and 2023.The investigation was limited to the last 15 years (2008-2022), yielding 587 articles containing these keywords.This study focused on "engineering" and "economics," delivering 506 mixed materials in articles, conference papers, book chapters, reviews, conference reviews, books, and editorials.Fig. 2 depicts the relatively steady amount of articles exploring railway financial restrictions, specifically between 21 and 43 papers indexed by Scopus annually.

Results of science mapping
After gathering papers relevant to the research topic, mapping was completed with the VOSviewer tool.This research uses VOSviewer to find terms, institutions, and nations useful for researching railroad procurement.

Co-occurrence of keywords
One study will always be related to another study of a similar nature.The extended investigation will serve as a preliminary study for additional research.All journals and proceedings will refer to one another (Fig. 3, Table 1).

Co-occurrence of keywords
If a journal article is linked to another, the researcher conducted a literature review utilizing papers from Scopus-indexed journals.Fig. 4 depicts the general mutual citation mechanism between these journal articles.Table 2 displays data on the number of citations for each document.Table 2 demonstrates that the transport policy journal and the Transportation Research Record are the two Scopus-indexed journals with the most citations and robust journal-to-journal relationship.

Findings
A summary of the research concerns concerning rail funding is derived from the three research processes depicted in Fig. 1.

Government funding
The government is in charge of ensuring the readiness of mass transportation, including both facilities and other supporting infrastructure.Trains are a one-of-akind of mass transit.Unlike different modes of mass transportation, preparation to use rail transit necessitates the government's completion of facilities and infrastructure.This is why rail transportation equipment is so expensive to operate.
Generally, railways are financed by the state through freight rates, income taxes, facility fees, licensing fees, grants, and loans.But, even maintaining the existing infrastructure is becoming increasingly difficult in this scenario.They are combined with the Covid-19 epidemic, which fully immobilized all sectors and a decrease in train passengers, which plummeted completely throughout the pandemic.The state bears the operational and maintenance expenditures of this mass transit system.As a result, the government of India has begun to seek the private sector for greater participation in this funding modality [17][18].

Financing with a variety of different options
Due to the numerous funding constraints in the railway industry, each country has developed its financing structure based on benchmarking in other countries.Multiple solutions can be employed to advance railway projects across the country.Some of these finance solutions were used during project construction, others were implemented during operation, and others were implemented during maintenance, with variations in between.For example, all rail financing in India has migrated to the private sector.Because passenger costs cannot pay train operational costs, the private sector uses land near the station to finance railway operational costs (asset commercialization) [20], in contrast to the Chinese railway system, where the government still controls railway finance.However, due to the difficulty in paying for the railway construction in Wuhan, the government focused on exploiting the growth in land values to close the funding gap for the train [17][18]21].
In addition to alternative land uses near railroad tracks, the Spanish government is attempting to divide railway management between the government and the private sector.The private sector focuses on larger railway projects, whereas the state manages smaller, less expensive ones [3].The London railway manager implemented another option.A congestion fee was established in London.Public transit, such as railways, subsidizes automobile drivers' congestion costs.Numerous other cities have similarly used gasoline tax income to finance public transportation.
Meanwhile, the Bangkok train system will be subsidized using company tax [21].General Budget Appropriations, Specific-Purpose and Securitized Borrowing, Public-Private Partnership (PPP), Concessions and Franchises, Project Financing, and Private Equity are the most common types of infrastructure financing in Ghana.Yet, for the success of railway infrastructure development, these funding options rely mainly on government monitoring and evaluation [22].

Public-private partnership
PPP are a newer strategy.Several countries have used the PPP method on various projects besides railroads.Solar energy development projects [23][24], toll roads [25][26][27], clean water supply [28], and other infrastructure provision projects are examples.A benchmarking can be generated from all that has been implemented and applied to railway projects.
China has so far developed railway projects entirely with state funds.But, as the construction of the Urban Transit train required massive money, the government began to appeal to the private sector to participate in the railway's development.PPP schemes have been implemented in several cities, including Shenzhen, Shanghai, Lanzhou, Urumqi [29], Japan, the United States, and the United Kingdom.Europe also uses the PPP approach to develop railway infrastructure [1].
PPP has also played a leading role in developing and enhancing railway projects in France.In 2010 and 2012, the French government appointed the French Rail Infrastructure Manager (RFF), reinforced by completing two HSK-East projects worth 15 billion Euros.The state cannot provide such a significant sum without collaboration with private organizations via PPP schemes and concessions.According to Dehornoy [30], payment-based (user charge) business organizations holding benefits receive commercial income (tariffs or any fees) but no government payment during the concession time.The state keeps the cost of passenger fares during the service availability-based (AP) concession period to be paid to business entities during the concession period [31].

Future studies
The final study question examined in the next section is about railway finance using the PPP plan.Project management, including risk management, can also be handled under the PPP system for financing railway projects [17][18][32][33].

Conclusion
Bibliometric analysis is quite helpful in searching and categorizing publications.The essence of the 506 articles on railway funding completed over 15 years (2008-2022) is that every country seeks a way out of the train funding dilemma.Some examples of innovative funding that can be derived from these articles are: 1. State-funded completely; 2. All funding comes from the private sector; 3. Options for rail transportation financing; 4. Financing distribution between the public and private sectors (PPP).Among the choices discussed, financing through the PPP plan is the best option because it can minimize the government's budget.Relevant research for further study is the financing of railways through the PPP plan and an analysis of the system's dangers.

Fig. 1 .
Fig. 1.Steps for doing a literature review on rail financing.

Fig. 4 .
Fig. 4. Mapping of journal article sources used in this study.

Table 1 .
Summary of the most frequently researched terms in rail financing.

Table 1 (
continued).Summary of the most frequently researched terms in rail financing.

Table 2 .
Source analysis in railway financing.