Rail transport - The Sustainability Management Wiki

Authors: Svea Poppen, Marieke Spellmeier, Polina Schröder, Henrik Sykora
Edited by: –
Last updated: October 9, 2025

Executive summary

Rail transport is a key component of sustainable mobility, offering significant environmental, social, and economic benefits. It produces far fewer greenhouse gas emissions compared to road and air transport, making it an essential solution for reducing carbon footprints. Electrification and alternative propulsion technologies, such as hydrogen and battery-electric systems, further enhance sustainability by minimizing reliance on fossil fuels.

Social sustainability is influenced by affordability and accessibility. Initiatives like Germany’s €9 ticket demonstrate how pricing strategies can promote equity, though challenges remain in balancing comfort and cost. Technological advancements, including automation and digital solutions, improve safety, efficiency, and passenger experience while creating new job profiles.

Economic sustainability depends on infrastructure development and resource efficiency. High-speed rail projects can stimulate economic growth but require careful planning to avoid uneven regional benefits and excessive costs. Strategic frameworks, such as the UK’s Sustainable Rail Strategy and BCG’s five-lever model, provide actionable measures for achieving net-zero emissions and fostering Innovation.

Despite these advantages, barriers persist. High investment costs, political decisions, and cross-border complexities hinder rapid progress. Overcoming these challenges demands collaboration among governments, industry stakeholders, and technology providers. Rail transport’s future lies in integrating ecological, social, and economic considerations to create resilient, efficient, and inclusive Systems.

1 Definition and relevance

Rail is defined as a terrestrial mass transport system, operating on fixed tracks. The most common form is the concept of a train, consisting of at least one self-motorized (diesel) or transmitted powered railcar and optionally coupled wagons that transport the traffic goods. Two modes of transportation can be distinguished, passenger rail transport and freight rail transport, which are usually operated separately. Railway is capable to cover any distance for freight, passenger transport distance is limited due to external factors.¹ Furthermore, some regions and countries operate a high-speed rail (HSR) network. Depending on the region, these types of rail transport can be operated on the same rail network or on separate systems. According to Pyrgidis, a HSR track system has to fulfill 3 criteria:

Vmax ≥ 200 km/h ;
Length ≥ 150 km ;
Vaverage ≥ 150 km/h²

While the entire global transport sector is responsible for about 25% of all CO2 emissions, the relative emissions of passenger and rail freight transport are significantly lower than those of other modes of transport, in some cases many times lower.³

This is primarily due to the energy efficient basic conditions in rail transport, the low rolling resistance, and the associated possibility of transporting high capacities of freight or passengers with few drive units compared to other means of transport.⁴ Per passenger kilometre, German long-distance transport emits only about one third of the greenhouse gases of private motorised transport at a similar level of pollution³, per tonne-kilometre of freight, it is 15% compared to the lorry.⁵

The statistics make clear that an expansion of rail transport at the expense of other means of transport would have an emission-reducing effect in the transport sector. Without the external costs resulting from factors such as noise and environmental pollution, the conditions for freight transport by road are more favourable which results in a higher share in the modal split, but if these costs were included, significantly more freight transport would be shifted to rail, since the external costs there are about one third of those of road freight transport.⁶

The design of different rail transport networks and their popularity depends largely on various geological, economic, political, social and especially historic factors. This can result in incompatibility problems when trying to connect rail networks internationally to meet the needs of modern transport requirements,⁷ so rail infrastructure expansion should be thought supranational.³

2 Sustainability impact and measurement

Rail transport exerts a variety of influences on sustainability. In this section of the research, these impacts are divided into the different dimensions of sustainability. Here, the section is divided into impact on the planet (environmental sustainability), people (social sustainability) and profit (economic sustainability). For each aspect, different methods for measuring sustainability are presented. It is important to note that impacts can vary depending on the region, the state of the infrastructure and the type of rail transport.

2.1 Ecological sustainability

Ecological sustainability describes the balance of the earth’s ecological system. Here, anthropogenic emissions are considered in relation to natural resources. Anthropogenic emissions are gases that enter the atmosphere as a result of human activity.⁸ These are caused, for example, by the release of CO2 emissions during the generation of energy from fossil fuels. Due to the economic upswing of the transport sector, the consequences of environmental pollution are increasing. The reason for this is an increased use of the various transportation options. Here, the impact of the transport sector, including rail transport, can be measured in terms of greenhouse gas emissions. It is estimated that 14% of the total pollution of the environment is caused by the transport sector.⁹ Domestic flights account for the highest proportion of greenhouse gas emissions in Germany, at 214 g/km. This is closely followed by emissions from passenger cars, which amount to 154 g/km. The greenhouse gases emitted by rail transport are only 29 g/km for long-distance trains in Germany, but values vary in othr regions depending on the energy mix.¹⁰

Here, it is important to note which types of drive the trains use. The use of electrically powered trains is a more environmentally friendly mode of transport, which means that less CO2 is emitted. The prerequisite for this is the environmentally friendly production of the electricity used, in order to keep the CO2 emissions low in the overall consideration. However, it must be noted that the use of clean energy is only 32.07% on average. Rail transport shows an overall negative significant correlation on environmental impact. Compared to this, air traffic shows a positive significant correlation. With an increase in the number of rail passengers, the environmental impact increases by only 1.63% to 4.41%, while for air traffic the values for the same increase range from 2.2% to 7.69%.¹¹ From this it can be concluded that with an increase in rail travelers and a decrease in air and car travelers, the increase in greenhouse gases in rail transport increases, but the increase is significantly less than the decrease in emissions in the area of air and car transport. Similar observations can be made for freight transport. If transport is shifted from road to rail, 32% of emissions can be saved with an electrically powered train, but only 3% with a diesel-powered train. This comparison is made with a road utilization of 50%. The German electricity mix is also considered, which at the time of the observation was 50% fossil fuels. Further environmental influences are the air pollution, which goes along with the environmental pollution and is also measured by greenhouse gas emissions and CO2 emissions.

From the various measurements of the impacts of rail transport, it can be concluded that it has a fundamentally positive influence on environmental sustainability. However, it must be taken into account whether the rail transport is electrically, or diesel powered, as the emissions are only slightly lower with a diesel-powered train. In addition, the electricity mix of the respective country must be considered for an electrically powered train. If the electricity comes from renewable energy sources, then train traffic in this area has a much lower level of CO2 emissions.¹¹

2.2 Social sustainability

Social sustainability refers to the conscious design and long-term maintenance of systems or organizations to promote and ensure the well-being of people, both in the present and for future generations. It involves considering and meeting human needs by promoting social equity, justice, and equality of opportunity. A key aspect of social sustainability is the creation of a political balance to avoid discrimination, poverty and social inequality.¹² Rail transport shows strong influences on social sustainability in the expansion of high-speed trains. This can be measured by surveys and statistics of ticket sales. Using the example of China, social inequalities can be shown due to the increasing importance of high-speed trains. Furthermore, this example can be used to show which needs and desires the railroads should address for more comfortable use.

Currently, 59.4% of rail journeys are made by high-speed trains, while the other 40.6% use conventional trains. The volume of rail passengers has already increased to 3.37 billion passengers in 2018, which shows a significant increase in demand for these trains. The impact on social sustainability here is in the area of cost.¹³ The cost of a trip on these trains is significantly higher than that on conventional trains. This creates social discrepancies as those with higher incomes can afford the mode of transportation. As a result, riding the train becomes a premium mode of transportation and social equity is no longer given and not all income classes can afford the transportation. In addition, there are also passenger expectations for train travel. These expectations are a continuous WLAN availability, a good environment in the waiting area, acceptable conditions of the seats as well as no overcrowding of the trains.¹⁴ Also here it can be stated that by the requirements of the users a very comfortable and luxurious kind of the train journey is desired, which is reflected thereby in the prices and affects further for an inequality of the social groups. Another point of the social aspects is the more attractive design of the rail journey using Germany as an example. Here, the 9€ ticket for three months was introduced in 2022. This should help to make the local and regional train journeys possible for every person and to make the train journey more attractive. In addition, this ticket should relieve the citizens from the high fuel prices. The consequences of this ticket were overcrowded trains and stations, yet the ticket was sold 52 million times. Furthermore, a successor solution for the 9€ ticket was desired by the majority of German citizens. Here one can clearly see by the promotion of the course journey that a reduction of the course journey makes this more attractive for all social groups and age groups. This leads to a positive influence on the social factors, as this type resolves the social discrepancies and establishes a more social justice. However, it should be noted that this offer was limited, and it can be concluded that rail travel must become cheaper in order to ensure equal opportunities for all groups of the population.¹⁵ Another influence of rail transport and change in this area can be seen in the change in jobs. The German Aerospace Center is already researching methods to optimize the interaction between people and technology. This results in changing tasks for train and control center personnel, as well as new roles and job profiles in this industry. The research projects include strong developments in automation, which can lead to a user-centered design of future railroad workplaces. Furthermore, it was found that especially the driving of freight lines is very monotonous and tiring for the train driver.¹⁶ From this it was concluded that there is an optimal mix between a system for monitoring and manual driving. In addition, driving assistance systems are to be introduced, which should also contribute to energy-saving driving. The developments are to be developed up to driverless driving, so that only attendants are on the train, who are to receive support from the control center in the event of faults, or the train can be controlled manually by remote control. This development of the jobs shows a clear improvement of the jobs in the rail traffic. It can provide more safety for rail transport. The nature of jobs will change as a result, but the services for customers will also evolve and thus have a positive impact on social sustainability.¹⁷

2.3 Economic sustainability

The goal of economic sustainability is to ensure the long-term economic stability and development of a company or organization. It is about creating a sustainable economy based on the efficient use of resources and advanced technologies.⁸

The development of infrastructure plays a crucial role in economic growth. A well-developed and modern infrastructure is of great importance in driving a country’s economic growth. Improving infrastructure can reduce travel costs, attract foreign investment, and expand trade in common resources. This drives economic development. However, infrastructure development can also impact industrialization and cause what is known as a distribution effect. This means that the economic benefits are not evenly distributed among the population and different regions of a country. This can lead to imbalances. An example of this is the expansion of highspeed networks. This often leads to the promotion of the development of central cities, attracting investment and increasing economic activity. However, this can lead to smaller cities and regions being disadvantaged as resources and opportunities are unevenly distributed. Therefore, it is important to consider both the positive economic impacts and potential negative effects on population, environment and social equity when planning and implementing infrastructure projects. This will enable balanced development and achieve a more equitable distribution of benefits for all citizens.¹⁸

3 Strategic sustainability strategies and measures

3.1 Overview of strategic sustainability approaches in rail transport

Strategic sustainability strategy approaches in the railroad sector have different origins and can be categorized in academic approaches, and industry driven approaches. In this chapter, for each category at least one example will be analysed. Due to the fact, that in many countries the railroad infrastructure and operation is state-owned, sustainability concepts are also provided by them. The sustainable rail strategy of Great Britain will serve as as an example in this field. Consulting companies are also involved in providing concepts, exemplary for them key elements of the railroad sustainability approach from the boston consulting group (BCG) will be mentioned. In the academic debate, there is research on the efficiency of existing railroad concepts of specific regions, often compared to similar infrastructure in different countries. Especially the economic sustainability Highspeed Rail (HSR) infrastructure is well researched. The paper will take a view on different HSR network projects in the context of sustainability.

3.1.1 Sustainable rail strategy of Great Britain

In April 2022, the rail safety and standards board, which is an interface between British rail operators and stakeholders like politics, science and customers¹⁹ released a strategy guide, containing environmental and social measures to push the GB rail towards sustainability. The strategy contains the following ecological key points: Net zero carbon rail: Following the commitment of the UK government, the entire British railway sector aims to be CO2-neutral by 2050. The main polluter is currently the rail infrastructure sector “Network Rail” with about two thirds of the total volume. So-called “science-based target programmes”, which are to show the individual players clear measures for CO2 reduction, are implemented to help achieving this goal. One core strategy will be to maximise the service life of the infrastructure. The remaining part corresponds to rail transport propulsion, which is to achieve net zero mainly through complete electrification and displacement of diesel propulsion.

Clean air: Despite the relatively low emissions of particulate matter and nitrogen oxides, monitoring is massively expanded, as too little is currently known about certain effects. Causative sources are to be countered with technical innovation, and hot spots with particular pollution are to be improved with better air circulation.

Preparing for a changing climate: Changing climatic conditions should be considered in the construction of all infrastructure and integrated into guidelines. Incentives for intelligent, adaptive and resilient concepts should be created. Depending on the results of risk assessments in the individual countries, other infrastructure operators should be involved in order to create holistic concepts.

A railway for nature: The railways must fulfil a major responsibility resulting from its role as one of the largest landowners. Here, too, the government’s goal of achieving an increase in biodiversity of 10% by 2025 in the near future must be followed. Measures should be taken in cooperation with neighbouring third-party land and also contribute to net zero carbon.

Zero waste: The dissemination of approaches to the circular economy has hardly been spread in the rail sector so far. The preliminary stage of partial recycling and waste management is currently the focus. However, the aim is to think even further and implement future assets with the circular economy in mind.

A quieter railway: Noise from rail transport currently affects 1.5 million people in the UK. This number is likely to increase further due to real estate projects on rail infrastructure or new tracks.

Noise management is intended to improve both the customer experience and the working environment for employees. Guidelines and control instances are to be created in order to also increase the acceptance and quality of life of residents.

Protect and conserve water: Due to the cheap availability of water so far a stricter water management did not arise. This is to change, and significantly less water is to be used more efficiently. In addition, the railway is involved in about 20 cases of serious water pollution per year, and this number is to be reduced.

In addition, the strategy includes the following 4 social aspects:

Rail at the heart of communities: Regionally based population groups are to be actively involved in the design of the rail infrastructure in order to achieve a better adaptation to the needs of the users. For this purpose, partnerships between local administrations will be established to coordinate wishes and needs. Negative feedback is collected and evaluated.

Positive social value: The value delivered by the rail infrastructure should be maximized through investment and this social value should always be considered in decision-making. It measures the relative importance that people attach to the change in their quality of life.

Sustainable supply chain: Previous suppliers were selected on a project basis according to cost efficiency. To counteract this, the strategy envisages long-term cooperation with more innovative, adaptable companies that were previously unable to participate due to complicated award and procurement procedures. Therefore, e.g., tendering procedures should be simplified and result-oriented and innovations should be promoted.

An inclusive rail industry: Jobs should be attractive, health-promoting and challenging, every user group of the railway should also be represented in the workforce, and values and ethics should also be upheld in the supply chain. Jobs created in the renewable energy sector should be promoted.

For each of these points, the concept provides a timetable until 2050, which is again subdivided thematically and chronologically and clarifies which measures are specifically planned until 2025 and which are targeted in the medium and long term. Furthermore, responsibilities within the points are defined individually for infrastructure and passenger and freight transport operators.²⁰

3.1.2 Five lever model from Boston Consulting Group

The five lever model of the Boston Consulting Group (BCG) focuses on the reduction of Greenhouse Gas (GHG) emissions along the entire value chain of rail companies. It is based on the subdivision of emissions into 3 scopes according to the GHG Protocol.²¹ BCG lists three levers for reducing direct emissions. At first, the deployment of alternative drive-train technologies (see chapter 3.2 for a detailed overview), furthermore rising the energy efficiency and stretching the service life of assets to the maximum extent possible. The fourth lever focuses on Scope 2 and contains an improvement on the share of renewable energy sources. Lever 5 covers all measures dealing with promotion of sustainability alongside the value chain (Scope 3).²²

Lever one basically means the shift away from diesel-electric to grid-based electric drivetrains. As in 2020, 55% of energy consumption in the industry was diesel based. According to BCG, this share must shrink down to 4% to reach net-zero emissions by 2050. It is explained, that the starting point on the different continents is different. Where central Europe and Asia are making progress, the vast majority of America is diesel powered. Especially in the US, the infrastructure is not capable of transforming the track network to be driven by electricity and the investment costs would be too high to be economically sustainable. BCG suggests alternative technologies. The latest options are showcased in chapter 3.2.

Lever two is providing adjustment points which should improve energy efficiency. For example, drivers should be trained for the most efficient driving style. Software should support decision makers in calculation the ideal driving parameters. Aerodynamics, mechatronics and new materials are important for the manufacturers to develop the new generation of environmentally sophisticated trains.

Lever three focuses on improving utilisation to the maximum. Rail infrastructure has to become intelligent, meaning a better automatic communication of different actors on rail to minimize delays and disruptions. Also, the maintenance of infrastructure has to be monitored and serviced actively, to predict and prevent downtimes, if possible. For efficiency gains and improved competitiveness, especially beneath road transport, trains have to get longer.

Lever four, the improvement in the coverage of the electricity needs with renewable energy sources, was already taken into account by some of the biggest providers for rail services to reach their individual net-zero targets. Most common is the purchase of renewable-sourced energy.

Lever five gives advice how to address especially suppliers to promote sustainability improvements. Measures are improved monitoring and transparency, offers from the rail operators to their partners to share reporting standards and a reorganisation or the creation of specific sustainability management and monitoring jobs to enable sustainability projects.²³

3.1.3 Chinas high speed rail network sustainability

Following Japan as a model for economical sustainable HSR operation, China started to build its own HSR network in the 2000s. With around 42000 km in operation in 2022, the network length surpassed the HSR infrastructure outside China combined. However, it is in doubt that a HSR network in that dimension can be sustainable. While single connections between major economic zones like Shanghai and Beijing can be highly profitable, it is unlikely for other less developed regions. The Chinese Government planned to stimulate the economy in indirectly with better connectivity and directly with the demand on workforce and resources for construction of the infrastructure.²⁴ The question has to be asked, whether the whole network was carefully planned with a sustainable demand foundation or if the main target was to stimulate the economy during recession around 2008, opposing to the European rail infrastructure development during that time, especially in Spain.²⁵

As HSR infrastructure profitability evaluations of projects in other countries show, each connection must be thoroughly assessed. There are multiple reasons, why additional HSR infrastructure can be unsustainable. For example, rail baltica, a planned HSR connection between Poland and the Baltic States would be unsustainable due to too low demand and more attractive existing lower cost alternatives. The California High-Speed Railway, a planned HSR connection on the US West coast, connecting Los Angeles with San Francisco, gets a positive attestation in terms of social, environmental and even economic impact (however the construction progress is far beyond plan and a finalisation of the project is uncertain²⁶). HS2, a HSR network project in England between London, Birmingham, Sheffield, Manchester and Leeds, started in 2017, will be a highly efficient route in terms of passenger capacity, but the estimated costs already more than doubled form £43 to £104 billion. Initial cost estimations for railways are exceeded on average by 44,7%, 33,8% for tunnels and bridges.²⁷ In an analysis of the Basque Country HSR project, a lifecycle analysis of the environmental performance was performed. Even in the best case scenario, the operation savings would not outperform the GHG Emissions caused by construction and maintenance and net energy savings are expectable only after 55 years of service.²⁸ With this considerations, the rapid and vast construction of the Chinese HSR does not seem to be in line with all aspects of sustainability. There is a substantial amount of research about the Chinese HSR, but mostly provided by non-peer-reviewed and state owned or financed Chinese facilities. For example, in the article of Li and Foo sustainability is treated only one-dimensional in the economic context. They developed an Index that contains financial keypoints only to define the long term economical sustainability of selected HSR routes.²⁹

3.2 Sector-specific technologies for improving sustainability

3.2.1 Propulsion technologies

The development of new technological propulsion options for transport by rail, road, water or air, allow for various large potential improvements in terms of sustainability. Possible alternatives to conventional fuels may include the following:

Fischer-Tropsch diesel and kerosene: synthetic fuels derived from carbon monoxide and hydrogen, respectively, that can be used as diesel and kerosene alternatives.

Hydrogen: A zero-emission fuel created through water electrolysis or natural gas reforming. It is suitable for use in fuel cell vehicles as well as internal combustion engines.
Battery Electric Drive: A propulsion technology in electric cars that is based on rechargeable batteries.
HVO: Hydrogenated vegetable oil made from vegetable oils or animal fats that can be used to replace diesel.
DME: Dimethyl ether is a synthetic fuel made from natural gas or biomass that can be used as a diesel alternative.

The environmental impact of various propulsion types varies depending on factors such as raw material quality, manufacturing methods, and emission intensity. The assessment of sustainability necessitates an examination of the individual conditions of each application. Battery-electric propulsion is frequently highly energy-efficient, and hydrogen use can lower energy consumption. Today, both hydrogen and electrification have promising uses in rail transport and merit further investigation as alternative propulsion systems.³⁰

3.2.2 Electrification

The electrification of rail transport offers various advantages and opportunities in terms of sustainable development. These include price reductions, increased speed, improved punctuality, greater comfort and convenience for passengers, or the reduction of emissions.

Electrification of rail transport is an opportunity to replace diesel-powered railcars with potentially more environmentally friendly electric-powered ones.³¹ By switching to renewable energy sources, electrification of transportation reduces GHG emissions and resource consumption, boosting environmental and social advantages. Additionally, because renewable energy is more affordable and there may be savings on pollution permits, it boosts the long-term profitability of the train industry. Government incentive programs play an important part, but the substantial initial investment costs should be carefully considered as well.³² In the following, however, various more sustainable drive technologies are presented as examples that can contribute to the sustainability of the rail sector.

Overhead lines

The electrification of rail transport can be achieved through the use of overhead lines. This method is already widely used. In this case, an electric multiple unit train can be powered by electrical energy by drawing it from overhead lines located above the track via so-called pantographs on the train. However, this requires a good infrastructure of overhead lines if a train is to be electrically operated solely via these.³³ This often results in a two-component solution in which the train has an additional battery installed or continues to be powered by a diesel railcar.³⁴ The growing demands on electrical operation due to higher speeds and higher utilization are placing increasing stress on the overhead lines. This can lead to increased maintenance and repair work, which is of great relevance due to the high expected reliability of the trains. Here, for example, additive processes offer new possibilities. By means of a 3D print, parts can be manufactured faster and with less resource consumption, reducing the effort and the required maintenance time. In addition, this offers new possibilities to adapt design and function more quickly and to optimize them for operation.³⁵ However, the expansion of electrification via overhead lines is particularly investment-intensive and varies depending on country-specific conditions with regard to geography, electricity prices and political situation.³⁶

Battery electric

Electric trains can run on overhead power lines in addition to being powered by batteries. In order to overcome the sections of the route that would otherwise be covered by diesel drive, Deutsche Bahn, for instance, uses the overhead line system to charge batteries on the sections with overhead lines.³⁴ Increased battery capacity and availability of renewable energy sources have been key factors in this progress. This makes it possible to lower the GHG emissions caused by rail transportation. Additionally, battery-electric trains can increasingly replace diesel-powered ones as battery storage capacities increase.³⁷

For successful electrification, there are still obstacles to be solved, such as electricity quality and grid stability. In particular, issues like voltage variations, harmonics, and reactive power arise more frequently as a result of increased power generation from renewable sources, which are very erratic. The expansion, increased use, and loading of electrified rail networks exacerbate these issues. System faults, such as signaling and communication failures, are caused by the issues discussed. In consequence, this raises the safety concerns associated with rail operations. But if the capacity is underutilized or the power is of poor quality, this can also result in inefficient use of energy which leads to higher operation costs.³⁸ This issue can be minimized, for example, by using hybrid microgrid systems. These complex systems are made up of a variety of renewable generation and energy storage methods. The system’s adaptability allows fluctuations to be absorbed and load peaks to be better cushioned. It contributes to a consistent energy supply and high power quality. It can also help to reduce reliance on fossil fuels, which are routinely used to supplement energy supply in the rail industry. Such a grid, however, requires an intelligent load control mechanism to fulfill situational consumption. Renewable energy can be integrated into rail transportation in a variety of ways.

Here are two examples:

Photovoltaic systems on the roofs of trains in sunny regions.
Use of wind turbines and storage systems along rail lines.

The location of generation and storage systems is essential to the systems’ efficiency and efficacy. It is also critical in this scenario to address regional issues. It is obvious that using renewable energy sources can improve the efficiency and environmental friendliness of rail transportation. By increasing the stability of renewable energy sources in the system, hybrid drive alternatives reduce possible hazards such as dealing with peak power and high speeds.³⁹

3.3.3 Hydrogen fuel

The introduction of new propulsion technologies in rail transport aims to increase energy efficiency and environmental friendliness. Among the alternative propulsion systems, hydrogenpowered fuel cell trains occupy a promising position. The Alstom Coradia iLint is a showcase example of such trains, operating in Lower Saxony, Germany, with a range of 1000 km. This train uses hydrogen as fuel and produces only water vapor and heat during combustion. In terms of energy consumption, hydrogen-powered trains can provide significant reductions in energy consumption compared to conventional diesel trains, with hydrogen trains consuming up to about 49% less energy.⁴⁰

However, despite these promising benefits, there are challenges associated with using hydrogen as a form of propulsion for rail transport. Hydrogen production, storage, and distribution present technical and economic challenges. The limited availability of hydrogen refueling stations along the routes and the comparatively low energy density of hydrogen compared to diesel are also aspects that need to be addressed.⁴¹ It is emphasized that a combination of hydrogen and battery technologies could be a promising solution, as this could enable longer ranges and faster refueling times.⁴²

In the context of introducing green hydrogen as an alternative energy source overall, it is mentioned that hydrogen is a clean and efficient option. It is emphasized that the use of hydrogen can help reduce dependence on fossil fuels and eliminate harmful emissions. Converting hydrogen to electricity through fuel cells is a particularly environmentally friendly way to generate energy. In this context, hydrogen-powered trains could be a useful addition on non-electrified lines, which exist mainly in rural areas.⁴³

The studies and analyses indicate that hydrogen offers potential as a form of propulsion for rail transport, but is also associated with technical, economic and infrastructural challenges. Successful integration requires close cooperation between different players to promote investment and innovation. Overall, hydrogen can help to make rail transport more environmentally friendly and sustainable by helping to reduce greenhouse gas emissions and improve air quality. However, in order to make this technology competitive and profitable, more research and development as well as significant investment are still required.⁴⁴

A research study, in which the choice of propulsion technology is evaluated using country-specific criteria, provides an example use case. This study assessed whether technology is more environmentally friendly for rail freight electrification in each case in terms of cost-effectiveness. The alternatives considered include overhead line equipment (OLE), battery operation, hydrogen, and hydrogen-battery hybrids. In Norway, favorable electricity prices and high taxes on fossil fuels make hydrogen and batteries viable and competitive alternatives to diesel, while for the U.S. it appears that due to the already existing good OLE infrastructure and higher traffic density on rail, OLE is a competitive alternative to diesel propulsion.⁴⁵

3.4 Digital solutions and progress of intelligent systems

3.4.1 Asset management

Digital solutions and advancements can especially help to make asset management more sustainable. Also on this aspect, a few examples are presented below to provide insight into what data-based solutions can enable in the rail sector. In asset management, maintenance and operation in particular are often of great importance and often entail financial risks in particular, but also reputational risks in the event of prolonged operational downtime. This can be counteracted, for example, with the development of Smart Tracks. Smart tracks refer to rail systems that are supplemented by measuring instruments on the track that have a wireless connection to a cloud in which real-time information is compiled. With the help of these smart instruments, continuous and precise monitoring of the track condition, for example, can be made possible. To do this, the wireless-enabled instruments collect data at strategic locations on the loads and condition of the system, which can be analyzed using the cloud to provide an early assessment of potential risks.⁴⁶ In addition to the possibility of actively installing instruments on the track, so-called non-destructive technologies (NDT) can also be used to assess the condition of the rail network. For example, ground penetrating radar (GPR) and interferometric synthetic aperture radar (InSAR) can be used to analyze ballast conditions and other structural aspects. These technologies enable comprehensive monitoring that additionally goes beyond conventional inspections and is less intrusive to the immediate rail environment.⁴⁷

However, systems that combine big data with machine learning go one step further. In addition to optimized maintenance work, these can also contribute to improved stability of rail traffic. One use case for this technology is the detection of low-frequency fluctuations. These fluctuations may prevent the systems on the train from operating correctly, creating safety risks. This in turn disrupts operations and causes both economic and reputational damage. A well-designed learning algorithm fed with power stability data from the grid can increase the likelihood that necessary maintenance or trouble spots in the grid will be detected more quickly. This means that anomalies and grid instabilities can be detected more quickly and proactively incorporated into sustainable maintenance planning. The more data such an algorithm receives, the better fluctuations can be predicted and detected before they occur.⁴⁸

A similar concept is represented by Digital twins. They are also based on large amounts of data and are intended to represent as accurate a representation as possible of real assets that can be digitally modified and analyzed. For example, it may be possible to determine the emissions of a station or a (subway) station along its entire life cycle. Project information from different lifecycle phases can be integrated into such a digital twin, thus enabling better asset management and communication by allowing various options to be tested on the digital model and analyzed for their impact on environmental, financial and social concerns even before potential work is carried out at the site.⁴⁹

This shows some of the ways in which digital developments can help to drive efficiencies and early detection systems in particular. In addition to these opportunities, however, there are a number of other possibilities that should be examined for their individual and situational benefits. For example, data-driven technologies promote sustainability by, among other things, enabling a smoother operation, which in turn increases the attractiveness of the means of transportation, and also promote resource efficiency, in that early detection of weak points in the system can avoid costly repairs. This additionally leads to economic sustainability, as costs can be reduced and operational downtime can be reduced.

3.4.2 Service-related developments

However, in addition to efficient asset management, digitalization enables better management of growing urban populations and the resulting increase in environmental impacts. As a result, digital can be a valuable tool for expanding environmental, economic, and social opportunities. Two examples are offered below to give you an idea of the numerous technological and, in particular, data-based digital options accessible here.

Peak loads on urban rail networks and railroads are common at various times of the day, as a particularly high passenger traffic must be handled. Knowing such peak passenger numbers and related information, such as boarding location and travel periods, could aid in better distributing these loads and adjusting timetables. Existing turnstile data can be used to optimize route use, allowing for peak-load relief measures such as alternate routes or additional service. Communicating these options can help to reduce congestion and delays while also improving passenger comfort. This invention makes use of existing systems, lowering infrastructure costs and encouraging careful rail operating, which reduces infrastructure worries and maintenance costs. Because of this technological solution, bottlenecks can be resolved more effectively, trains can be assigned more efficiently, timetables can be more demand-oriented, and duty schedules for rail operators may be streamlined.⁵⁰ In the case of Unattended Train Operations (UTO), digital solutions go a step further. Through automation, this technology allows trains to run without a driver, which is very useful in mass transit. This decreases labor requirements, lowers operating expenses, and increases trip frequency, making rail travel more appealing and cost-effective. UTOs improve reliability by eliminating human errors. They also reduce rail line wear and tear, boosting system durability.

However, dangers like as system breakdowns and power outages continue to exist, necessitating personnel intervention for error or risk management.⁵¹ A combination of these two systems presented would also be an interesting option in order to be able to manage peak loads while maintaining the same level of staffing. Overall, these many techniques and technology demonstrate how digital solutions can make rail transportation more environmentally, socially, and economically sustainable and efficient. However, to enable optimal integration, such solutions require strong collaboration among technology developers, transportation authorities, and operators. The options offered provide a general overview of the extent of technical solutions and tools at various stages of maturity and integration effort. These must be assessed situationally and individually in terms of prospective deployment.

4 Drivers and barriers to sustainable rail transport

In the face of escalating environmental challenges and the urgent need to reduce carbon emissions, the sustainability of transportation systems has emerged as a critical concern worldwide. Among the various modes of transportation, rail transport stands as a promising solution due to its potential to significantly curtail greenhouse gas emissions, reduce congestion on roadways, and promote energy efficiency. This chapter aims to delve into the complex landscape of rail transport sustainability, exploring both the drivers that propel its adoption and the barriers that impede its progress. To embark on this journey, it is essential to establish a clear understanding of key terms and concepts. As established beforehand, sustainable development entails fulfilling the requirements of the present generation while safeguarding the capacity of future generations to fulfill their own necessities.⁵²

Therefore, a driver to sustainability entails actors, forces, or incentives that stimulate and push the adoption and advancement of practices, technologies, or policies aimed at achieving a state of sustainable development. These drivers can include economic, environmental, social, and technological factors that encourage the implementation of strategies that balance present needs with the long-term well-being of society, the environment, and the economy.⁵³ In the context of rail transport and this wiki, drivers of sustainability are catalysts that push for the adoption of practices and policies that make rail transportation more ecologically friendly, economically viable, and socially equitable. Barriers to sustainability are the obstacles, challenges, or constraints that hinder or impede the progress towards achieving sustainable outcomes. In the case of rail transport and this wiki, barriers to sustainability are the challenges that must be addressed to fully realize the potential benefits of rail transportation as a sustainable mode of transit.⁵⁴ In the following discussion, a distinction is made between internal and external factors that serve as drives or obstacles. External obstacles or drivers refer to variables that are outside the direct control or influence of the rail transport business. External obstacles might potentially impede growth or provide difficulties, but external catalysts can offer incentives or avenues for success. Internal obstacles or drivers are derived from elements that are within the jurisdiction or influence of the rail transport sector. Internal obstacles may arise from constraints within the organisational structure or operational procedures, while internal drives might manifest as strategic approaches or efforts implemented by the organisation to improve its overall performance.

4.1 Drivers

4.1.1 Environmental concerns

When looking at the drivers of sustainability, the first aspect researched are the environmental concerns as it is a powerful internal driver that compels organizations to reevaluate their practices and prioritize conscious solutions. There is a growing recognition among industries of the need to reduce their ecological impact. The use of rail transport is receiving significant attention as a potential solution to solve some environmental problems due to its inherent advantages in terms of reduced carbon emissions and energy usage.⁵⁵

In the urban setting, rail transport systems exhibit superior performance compared to road-based transportation in several aspects, including transport efficiency and reduced energy demands.⁵⁶ Urban rail systems possess unparalleled potential for efficiently transporting huge numbers of people, as seen by their high passenger throughput. Additionally, these systems often exhibit a relatively low energy consumption per passenger-kilometer travelled. Consequently, this mitigates the environmental and health concerns often connected with such emissions. The transition of long-distance travel from aircraft, particularly short-distance flights, and vehicles to conventional and high-speed rail systems is widely recognised as an energy-efficient approach that may provide substantial environmental benefits. The use of high-speed rail presents the only recognized low-carbon option to aviation, which is considered one of the most difficult sectors to decarbonize, particularly for the transportation of significant numbers of people over distances of around 1.000 km.⁵⁷

The primary advantages of transitioning goods movement from road or air to rail are enhanced efficiency and reduced pollution. This phenomenon arises due to the decreased energy need per unit of weight and distance for transporting products by rail. The railway industry is the most well-established sustainable alternative to trucks and is seen as one of the sectors that poses significant challenges in terms of decarbonization, particularly for the transportation of substantial quantities of goods across extensive distances.⁵⁸

However, it is still not clear from these statements how and why organizations are motivated to address environmental issues. In the following, internal drivers related to environmental concerns are analysed. Rail transport companies may demonstrate a strong internal commitment to promoting sustainability and assuming responsibility for environmental protection. This has the potential to stimulate efforts aimed at mitigating emissions, enhancing energy efficiency, and allocating resources towards sustainable practices within their operational frameworks. Even though rail transport could be considered to be one of the most sustainable transportation modes, the energy sources used still have a lot of potential to be more eco-friendly in some countries, for example the United Kingdom.⁵⁹

One of the primary environmental issues within the transportation industry is to the release of greenhouse gases, which have been scientifically associated with the phenomena of global warming and climate change. The objective of sustainable transportation is to mitigate adverse effects on both society and the environment, while simultaneously promoting social and economic welfare. Hence, it is essential for enterprises operating in the transportation industry to embrace sustainable development practices and focus on three main topics being economic advancement, societal welfare, and environmental considerations into their expansion plans. This approach will not only contribute to the resolution of urgent global challenges, but also foster enduring commercial prosperity and social advantages.⁶⁰

To achieve a more sustainable experience using less carbon, railway companies also must prioritize enhancing the efficiency of train operations and extending the lifespan of important equipment, since these measures are crucial for producing substantial annual income in addition to being more environmentally friendly. Although these acts are not often categorized within the context of decarbonization, they do provide measurable contributions towards reducing the carbon footprint related to railway transportation. From an emissions standpoint, the motivation to decrease service disruptions may not be readily apparent. The concept of service interruption comprises all instances of delays. The presence of the impacted train results in additional fuel consumption, hence exacerbating emissions.

Moreover, both the subsequent trains following the affected train and the opposing trains have prolonged idle time, which further contributes to the escalation of emissions and customer dissatisfaction.⁶¹ Moreover, internal drivers may also arise from the desire to innovate and gain a competitive advantage. Especially when considering the impact delay have on customer satisfaction and reputation. As sustainability has gained overall popularity among the population, a good reputation in terms of eco-friendliness is more important than ever. Developing sustainable products, processes, and services can differentiate an organization in the market and attract environmentally aware consumers. Not only consumers but also employees prefer organizations that align with their personal values, including environmental stewardship. Embracing sustainability as an internal driver can boost employee morale, engagement, and job satisfaction.⁶²

4.1.2 Safety enhancement

Railways generally have lower accident rates and provide a safer mode of transport compared to road vehicles, leading to improved safety outcomes. Safety can be considered an internal driver for several reasons, as it directly affects an organization’s operations, culture, reputation and overall performance. However, there are also laws and regulations binding railway companies to certain safety standards. Realistically, it is unattainable to achieve a degree of traffic safety that completely eradicates all potential hazards.⁶³

Yet, it is incumbent to the railways to mitigate the hazards using all available and rational methods. When evaluating business problems, it is imperative that safety issues be given equal priority to economic considerations. As an external driver, the General Railway Act in Germany establishes operator responsibility as a fundamental element of safety in rail operations, specifically outlined in Section 4.

Based on the above information, it is essential that railway infrastructures and vehicles adhere to the prevailing public safety standards throughout their first introduction to the market as well as during their operational lifespan.⁶⁴ Currently, technology techniques based on data collecting, processing, transmission, and storage are extensively employed to support railway traffic safety and security. As a result, safety, security, and cybersecurity should be seen as complimentary concerns that must be given on a comparable high level.⁶⁵

4.1.3 Public demand and expectations

Increasing public awareness of environmental issues and the demand for greener transportation options can drive the rail industry to prioritize sustainability externally. Public support and expectations can influence investments, infrastructure development, and the adoption of sustainable practices. Not only is there a need for a more sustainable railway system but also reliability, predictability and comfort must be improved. The ecological sustainability of rail transport can only persevere if it also costumer friendly and therefore frequently used. Only then is it sustainable, not only in the environmental sense, also in the long-term sustainability of the rail transport sector. Railway companies must realize that this interplay is important for their success and use it to strive towards a customer and environmentally friendly future.⁶⁶

As increasing incomes and populations in developing and emerging countries have resulted in significant urban growth, there is a rising need for transportation systems that are more efficient, quicker, and environmentally friendly. However, the desire for speed and flexibility often leads to a preference for private automobile ownership and air travel. The growth in demand for goods services is also influenced by the rise in incomes. This may be attributed to the significant increase in demand for the swift transportation of lighter and higher value items, which is directly correlated with higher income levels. The rail industry has many advantages that may be used to enhance its competitiveness in the market. However, achieving this would need more strategic investments in rail infrastructure, continued endeavors to enhance commercial com- petitiveness, and the adoption of technology innovations. All in all, the public demand for sustainable transport is as high as ever, forcing the industry to react and become more sustainable long term.⁶⁷

4.1.4 International agreements and standards

Compliance with international standards and commitments can be a driver for sustainability practices. Numerous international agreements, such as the Paris Agreement concerning climate change, define specific objectives and obligations aimed at mitigating greenhouse gas emissions and fostering sustainable practices. These commitments have the potential to serve as catalysts by establishing an international framework that incentivizes states and organizations to embrace more environmentally conscious strategies in order to fulfil their responsibilities. International agreements often promote the harmonization of national policies and laws with global environmental objectives, having the potential to compel states to enact domestic policies that promote the preservation of the environment and the pursuit of sustainable development.⁶⁸ The European Union has achieved complete liberalization of international road freight commerce among its member states. The Treaty of Rome, which led to the establishment of the European Economic Community, resulted in the liberalization of trade and freight movement inside the European Union. The treaty was enacted with the aim of implementing a common transport strategy that is rooted on free market principles, with the ultimate goal of removing obstacles that impede competition in the realm of international transport.⁶⁹

In conclusion, the factors driving sustainability in the realm of rail transport are diverse and of utmost significance. Environmental problems serve as a catalyst, compelling organisations to reevaluate their practises and choose sustainable solutions. The inherent advantages of rail transport, such as its capacity to decrease emissions and enhance energy efficiency, make it a very appealing environmentally sustainable option. Urban rail systems are very effective in transporting people while using minimum energy, therefore immediately addressing problems related to the environment and public health. The energy efficiency of high-speed rail is further emphasised by its potential to replace air travel.

The transition of commodities movement to rail infrastructure has been shown to improve operational efficiency, mitigate environmental pollution, and contribute to efforts aimed at reducing carbon emissions. Safety has a crucial role as an internal catalyst, exerting influence on operational culture, reputation, and overall performance. The increasing public demand for sus- tainable transport has prompted the train industry to allocate resources towards enhancing customer experience and developing infrastructure. International agreements establish worldwide standards, advocating for the use of environmentally conscious approaches.

Furthermore, the pursuit of innovation and the desire for competitive advantage are closely linked to the goals of sustainability. When organisations connect themselves with environmental ideals, they cultivate consumer loyalty and enhance staff engagement. At the heart of these forces lies a key inquiry: what are the underlying factors that propel rail transport companies?

The solution may be found in their shared dedication to environmental stewardship, prioritization of safety protocols, emphasis on consumer contentment, and adherence to international benchmarks. In essence, it is the aforementioned forces that steer rail transport firms towards a future characterized by sustainability, resilience, and achievement.

4.2 Barriers

Expanding rail infrastructure and maintaining existing networks require substantial investments, which can be a significant barrier to sustainable development in rail transport. The length of conventional passenger and freight rail lines has hardly expanded over the previous two decades, suggesting minimal new infrastructure. North America has the longest conventional rail network, followed by Europe, Russia, India, and China. Since 2000, high-speed rail has more than sevenfold risen globally. The European Union, the first to build an international rail network, has seen moderate but steady growth in urban and non-urban rail travel in recent decades.

Some passenger traffic is now high-speed rail.⁷⁰ However, when looking at the rail infrastructure of Germany, the major urban centers of Berlin, Hamburg and Munich benefit most from the rail system. Because of their importance, rail lines were built in past centuries and are still being built today to shorten travel times to and from these major centers, giving them a locational advantage that they would not have on their own due to their geographic location. However, apart from these metropolitan cities, Germany is lacking reliable and sufficient infrastructure in terms of their rail transport.⁷¹

Long-term, this obstacle may be overcome, particularly in Germany. The rectification of deficiencies in infrastructure development during the last two decades is not an immediate undertaking. In order to facilitate the development of more infrastructure, it is important to enhance the capacity of planning and construction resources, hence enabling the management of a greater number of projects. In the subsequent phase, a much larger amount of financial resources is required. In this regard, the German government has taken action and declared a substantial increase in funding for the railway system via the implementation of an augmented truck toll. However, specifics about this initiative remain undisclosed. According to Böttger, a potential solution to increase capacity in the near term would include conducting a thorough evaluation and subsequent streamlining of current technical and operational regulations. There seems to be a significant potential in this context.⁷² Again, technical advancements and more sustainability is only achievable long term if the options are available to the costumers and comfortable as well as affordable to use. The railway infrastructure has to be improved, as seen in Germany. Sustainability can only be achieved if rail infrastructure is expanded to facilitate the switch to climate-friendly modes of transport. This assures that railway is accessible to (potential) customers and therefore used.⁷³ The failure to provide sufficient infrastructure to accommodate the needs of the customers not only in metropolitan cities is mostly due to financial limits which is further elaborated in the next section. Rail companies may face financial constraints when investing in sustainable technologies, infrastructure upgrades, or operational improvements. This external barrier can also be internal, meaning the incorrect or insufficient allocation of resources within a company. Limited financial resources can impede progress in achieving sustainability goals. The use of digital technologies facilitates intelligent communication and collaboration among rail vehicles, rail infrastructure, consumers, rail staff, and value-added partners. This integration, together with the incorporation of innovative elements such as new materials and drives, leads to a reduction in costs and emissions, as well as an enhancement in queue capacity and customer satisfaction. Rail technology is characterised by its high cost, extended operational lifespan, and reliance on a multitude of components, technologies, and suppliers. In regions with low population density, the limited demand for transport poses challenges in establishing cost-effective mobility networks, especially in relation to components such as timetables and routes. Additionally, the need for driving personnel for the initial and end segments further complicates the situation.⁷⁴

This is also evident in the increasing international cross border goods transports. There exists a broad consensus about the significant role played by the decrease in costs associated with longdistance transportation and communication in driving the process of globalization. In the past, commerce expenditures were not regarded as significant factors in the global commerce framework and volume. However, their importance has now been recognized. Extended customsclearance and border-crossing procedures have the potential to cause delays and disturbances in the context of international vehicle traffic. It is projected that the volume of road freight transport in the European Union would see a significant growth of 78% from 2000 to 2030.⁶⁹

However, especially in Germany there seems to be a rather political debate on how sustainable railway is going to be supported financially and therefore, how to improve sustainable technology and the infrastructure. This is not only evident in Germany but also in other countries where political decisions influence the allocation of financial resources, further complicating the process and creating an even stronger external barrier. One example for a political measure is tax funding, being a widely embraced practice due to its potential for politicians to establish themselves as influential figures in policy-making.⁷⁵

4.3 Conclusion

The challenges faced by the rail transport sector in its efforts to achieve sustainability are many and significant. Infrastructure development poses a major impediment. The expansion and maintenance of rail networks need significant financial expenditures, which may impede the achievement of sustainable development goals.

The presence of financial limitations poses additional obstacles to the implementation of sustainability initiatives. Railway firms may have challenges in efficiently allocating resources, which might impede their ability to invest in environmentally friendly technology and infrastructure enhancements.

Barriers are also encountered in the context of international cross-border commodities transportation. The recognition of the importance of cost reduction in long-distance transportation and communication within the framework of globalisation is well-established. However, it should be noted that the implementation of extensive customs-clearance and border-crossing processes has the potential to cause delays and disruptions.

Additionally, political choices are of utmost importance in addressing and surmounting these obstacles. These choices have a significant impact on the development and progress of sustainability projects, giving rise to various possibilities and problems.

It is essential to acknowledge that the impediments constitute but a portion of the many problems encountered by the rail transport sector in its pursuit of sustainability. Additional study may lead to the identification of the following barriers: Public Perception and Image, Cultural and Organisational Change, Supply Chain Complexity, and study and Innovation. To surmount these obstacles, it is essential to adopt a holistic and cooperative strategy. Collaborative efforts among governments, regulatory agencies, train operators, academics, and stakeholders are important to effectively tackle these difficulties.

References

1
Pyrgidis, Christos. Railway Transportation Systems; Taylor & Francis Group, (2022), p. 1.
2
Pyrgidis, Christos. Railway Transportation Systems; Taylor & Francis Group, (2022), p. 22.
3
Janson, Matthias. So viel Treibhausgas emittieren Flugzeug, Bahn & Co, (2023) https://de.statista.com/info-grafik/18952/treibhausgasemissionen-nach-verkehrsmitteln.
4
ABB. Transporteffizienz steigern. Vorteile und Chancen des beschleunigten Übergangs zu nachhaltigem Verkehr, (2021) https://www.energyefficiencymovement.com/wp-content/uploads/2021/10/ABB_EE_WhitePa- per_Transportation_final_DE.pdf.
5
Allianz pro Schiene. Höhe der Treibhausgas-Emissionen im deutschen Güterverkehr nach Verkehrsträgern im Jahr 2019, (2021), https://de.statista.com/statistik/daten/studie/881600/umfrage/co2-emissionen-im-deutschen- gueterverkehr-nach-verkehrsmitteln/.
6
Zak, Jolanta et al.. The role of railway transport in designing a proecological transport system, Computers in Railways XIV Special Contributions. 15-26 (2015).
7
Pawlik, Marek. Analyse of the challenges for safe transition individual intraoperable railway systems to the sin- gle European interoperable railway system. Archives of civil engineering, 62(4), 169-180 (2016), p. 174-175.
8
Pufé, Iris. Nachhaltigkeit. Stuttgart: UTB. p.101.
9
Gyamfi, Bright et al. Beyond the environmental Kuznets curve: Do combined impacts of air transport and rail transport matter for environmental sustainability amidst energy use in E7 economies?. Environment, Develop- ment and Sustainability. 24. 11852-11870 (2022), p. 11853.
10
Allianz pro Schiene. Höhe der Treibhausgas-Emissionen im deutschen Personenfernverkehr nach Verkehrsträ- gern im Jahr 2019 (in Gramm pro Personenkilometer). In Statista. (2021) https://de-statista-com.proxy02a.bis.uni-oldenburg.de/statistik/daten/studie/322971/umfrage/hoehe-der-schadstoffemissionen- durch-fernverkehr/
11
Gyamfi, Bright et al. Beyond the environmental Kuznets curve: Do combined impacts of air transport and rail transport matter for environmental sustainability amidst energy use in E7 economies?. Environment, Develop- ment and Sustainability. 24. 11852-11870 (2022), p. 11863.
12
Pufé, Iris. Nachhaltigkeit. Stuttgart: UTB. p.102.
13
Ren, Xiaohong et al. Impact of high-speed rail on social equity in China: Evidence from a mode choice sur- vey. Transportation Research Part A. 138 (2020). 422-441. p. 423
14
Ren, Xiaohong et al. Impact of high-speed rail on social equity in China: Evidence from a mode choice sur- vey. Transportation Research Part A. 138 (2020). 422-441. p. 424
15
Statista Research Department. Das 9€ Ticket, (2023). https://de-statista-com.proxy02a.bis.uni-olden- burg.de/themen/9462/9-euro-ticket/#topicOverview
16
Naumann, Anja, Grippenkoven, Jan. Bahnarbeitsplätze im Wandel. EIK – Eisenbahn Ingenieur Kompendium. DVV Media Group. ISSN 2511-9982 (2023). 296-302. p. 296.
17
Naumann, Anja, Grippenkoven, Jan. Bahnarbeitsplätze im Wandel. EIK – Eisenbahn Ingenieur Kompendium. DVV Media Group. ISSN 2511-9982 (2023). 296-302. p. 297-298.
18
Wang, Luqi et al. The Impacts of Transportation Infrastructure on Sustainable Development: Emerging Trends and Challenges. International Journal of Environmental Research and Public Health. 15(1172). 1-24 (2018). p. 3.
19
RSSB. Sustainable Rail, (2021) https://www.rssb.co.uk/who-we-are/about-us/sustainable-rail.
20
RSSB. Sustainable Rail Strategy, (2022) https://www.rssb.co.uk/sustainability/sustainable-rail-strat-egy#:~:text=This%20SRS%20Prototype%20is%20a%20vital%20stepping%20stone,is%20re-quired%20if%20ambitions%20are%20to%20be%20realised.
21
World Business Council for Sustainable Development. World Resources Institute: The Greenhouse Gas Proto- col. Accounting and Reporting Standard. Hg. v. W. R.I. WBCSD, (2004), p. 27-29.
22
Zawadski, Annika et al. Riding the Rails to Sustainability. Boston Consulting Group, (2022), p. 5, https://www.bcg.com/publications/2022/riding-the-rails-to-the-future-of-sustainability.
23
Zawadski, Annika et al. Riding the Rails to Sustainability. Boston Consulting Group, (2022), p. 6-14, https://www.bcg.com/publications/2022/riding-the-rails-to-the-future-of-sustainability.
24
High Speed Rail Development Worldwide. Environmental and Energy Study Institute, (2018) https://www.eesi.org/papers/view/fact-sheet-high-speed-rail-development-worldwide.
25
Islam, Dewan. Prospects for European sustainable rail freight transport during economic austerity. Bench- marking: An International Journal vol. 25 iss. 8. 2783-2805 (2018) p. 2796
26
Tunnicliffe, Andrew. Will California ever get its high-speed rail? Railway Technology, (2023), https://www.railway-technology.com/features/will-california-ever-get-its-high-speed-rail/?cf-view.
27
Watson, Inara, Ali, Amer & Bayyati, Ali. Sustainability of high-speed rail: a comparative study. Proceedings of the Institution of Civil Engineers – Transport, (2018).
28
Bueno, Gorka, Hoyos, David & Capellan-Perez, Inigo. Evaluating the environmental performance of the high speed rail project in the Basque Country, Spain. Research in Transportation Economics vol. 62, 44-56 (2017).
29
Yuanhui Li & Check-Teck Foo. Towards sustainability in the high-speed railway industry: modeling of cases from China. Chinese Management Studies, 8(4), 624 – 641 (2014).
30
Breuer, J.L.; Scholten, J.; Koj, J.C.; Schorn, F.; Fiebrandt, M.; Samsun, R.C.; Albus, R.; Görner, K.; Stolten, D.; Peters, R. An Overview of Promising Alternative Fuels for Road, Rail, Air, and Inland Waterway Transport in Germany. Energies, 15 (4), 1443 (2022), p. 32, 47.
31
Röpcke, T., Windt, A. Umstellung liniengebundener Fahrzeuge auf alternative Antriebstechnologien. Sonderprojekte ATZ/MTZ 24 (Suppl 2), 36–39 (2019), p. 36 – 38.
32
Mitrofanov, S.V.; Kiryanova, N.G.; Gorlova, A.M. Stationary Hybrid Renewable Energy Systems for Railway Electrification: A Review. Energies, 14, 5946 (2021), p. 16.
33
Zweig, BW., Stephan, A.. Energieversorgung elektrischer Bahnen. In: Fendrich, L., Fengler, W. (eds.) Hand- buch Eisenbahninfrastruktur. Springer Vieweg, Berlin, Heidelberg (2019), P. 724 – 727.
34
Deutsche Bahn AG, Wir laden Züge elektrisch auf. https://nachhaltigkeit.deutschebahn.com/de/massnah- men/akkuzuege (2023).
35
Lee, K., Jung, H. An improvement of manufacturing process using 3D printing technology for overhead line components on railway electrification. J. Electr. Eng. Technol., 17, 3085–3091 (2022), p. 3085.
36
Zenith F, Isaac R, Hoffrichter A, Thomassen MS, Møller-Holst S. Techno-economic analysis of freight rail- way electrification by overhead line, hydrogen and batteries: Case studies in Norway and USA. Journal of Rail and Rapid Transit, 234 (7), 791-802 (2020), p. 802.
37
Popovich, N.D., Rajagopal, D., Tasar, E. et al. Economic, environmental and grid-resilience benefits of con- verting diesel trains to battery-electric. Nat Energy, 6, 1017–1025 (2021), p. 1017 – 1020.
38
S. M. Mousavi Gazafrudi, A. Tabakhpour Langerudy, E. F. Fuchs and K. Al-Haddad, Power Quality Issues in Railway Electrification: A Comprehensive Perspective. IEEE Transactions on Industrial Electronics, 62 (5), 3081 – 3090 (2015), p.3081 – 3082.
39
Mitrofanov, S.V.; Kiryanova, N.G.; Gorlova, A.M. Stationary Hybrid Renewable Energy Systems for Railway Electrification: A Review. Energies, 14, 5946 (2021), p. 8 & p. 14 – 15.
40
Breuer, J.L.; Scholten, J.; Koj, J.C.; Schorn, F.; Fiebrandt, M.; Samsun, R.C.; Albus, R.; Görner, K.; Stolten, D.; Peters, R. An Overview of Promising Alternative Fuels for Road, Rail, Air, and Inland Waterway Transport in Germany. Energies, 15 (4), 1443 (2022), p. 30 – 31.
41
Zenith F, Isaac R, Hoffrichter A, Thomassen MS, Møller-Holst S. Techno-economic analysis of freight rail- way electrification by overhead line, hydrogen and batteries: Case studies in Norway and USA. Journal of Rail and Rapid Transit, 234 (7), 791-802 (2020), p. 798 – 800.
42
Mitrofanov, S.V.; Kiryanova, N.G.; Gorlova, A.M. Stationary Hybrid Renewable Energy Systems for Railway Electrification: A Review. Energies, 14, 5946 (2021), p. 17
43
Kruse, M., Wedemeier, J. Potenzial grüner Wasserstoff: langer Weg der Entwicklung, kurze Zeit bis zur Um- setzung. Wirtschaftsdienst 101, 26–32 (2021), p. 1 – 5.
44
Atteridge WJ, Lloyd SA. Thoughts on use of hydrogen to power railway trains. Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy. 235(2), 306-316 (2021), p. 306 – 308.
45
Zenith F, Isaac R, Hoffrichter A, Thomassen MS, Møller-Holst S. Techno-economic analysis of freight rail- way electrification by overhead line, hydrogen and batteries: Case studies in Norway and USA. Journal of Rail and Rapid Transit, 234 (7), 791-802 (2020), p. 801.
46
Edwards, J.R.; Mechitov, K.A.; Germoglio Barbosa, I.; de O. Lima, A.; Spencer, B.F., Jr.; Tutumluer, E.; Dersch, M.S. A Roadmap for Sustainable Smart Track—Wireless Continuous Monitoring of Railway Track Condition. Sustainability, 13, 7456, (2021), p. 1 – 2, 12 – 13.
47
Ferrante, C., Bianchini Ciampoli, L., Benedetto, A. et al. Non-destructive technologies for sustainable assess- ment and monitoring of railway infrastructure: a focus on GPR and InSAR methods. Environmental Earth Sci- ence 80 (806), (2021), p. 1 – 2, 17.
48
Gonzalez-Jimenez D, Del-Olmo J, Poza J, Garramiola F, Madina P. Data-Driven Low-Frequency Oscillation Event Detection Strategy for Railway Electrification Networks. Sensors23 (254), (2023), p. 1 – 3.
49
Kaewunruen S, Peng S, Phil-Ebosie O. Digital Twin Aided Sustainability and Vulnerability Audit for Subway Stations. Sustainability, 12(19), (2020), p. 1 – 2, 14.
50
Haodong Yin, Jianjun Wu, Zhiyuan Liu, Xin Yang, Yunchao Qu, Huijun Sun. Optimizing the release of pas- senger flow guidance information in urban rail transit network via agent-based simulation. Applied Mathemati- cal Modelling, 72, 337-355 (2019), p. 337 – 340, 353 – 354.
51
Cohen, J. M., Barron, A. S., Anderson, R. J., & Graham, D. J.. Impacts of Unattended Train Operations on Productivity and Efficiency in Metropolitan Railways. Transportation Research Record, 2534(1), 75 – 83 (2015), p. 75 – 76, 78 – 82.
52
United Nations. Sustainability. https://www.un.org/en/academic-impact/sustainability (1987).
53
Ivic, A., Saviolidis N. A. & Johannsdottir, L. Drivers Of Sustainability Practices And Contributions To Sus- tainable Development Evident In Sustainability Reports Of European Mining Companies (2021) p. 12 – 19.
54
Duarte, F. Barriers to Sustainability: An Exploratory Study on Perspectives from Brazilian Organizations. Sus- tainable Development 23 (6), 425-434 (2015), p. 425 – 427.
55
Smith, R. A. Railways: How They May Contribute To A Sustainable Future. Proceedings of The Institution of Mechanical Engineers Part F-journal of Rail and Rapid Transit 217 (4), 243-248 (2003), p. 245.
56
Smith, R. A. Railways: How They May Contribute To A Sustainable Future. Proceedings of The Institution of Mechanical Engineers Part F-journal of Rail and Rapid Transit 217 (4), 243-248 (2003), p. 246.
57
IEA, The Future of Rail – Opportunities for energy and the environment. International Energy Agency (2019), p. 97.
58
IEA, The Future of Rail – Opportunities for energy and the environment. International Energy Agency (2019), p. 100 – 101.
59
Givone, M., Brand, C. & Watkiss, P. Are Railways Climate Friendly? Built Environment 35 (1), 70-86 (2009), p. 70 – 76.
60
Moradi, S., Ahadi, H. R. & Sierpinski, G. Sustainable Management of Railway Companies Amid Inflation and Reduced Government Subsidies: A System Dynamics Approach. Sustainability 15 (4), 111176, (2023), p. 2 – 3.
61
Wang, Y., De Blois, S. & Oldknow, K. D. Incentivized decarbonization through safer and more efficient heavy haul operations. Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit, (2023).
62
Wang, Y. et al. The Impact of Service Quality and Customer Satisfaction on Reuse Intention in Urban Rail Transit in Tianjin, China. SAGE Open 10(1), (2020), p. 1.
63
Dongyang, Y. et al. A railway accident prevention method based on reinforcement learning – Active preven- tive strategy by multi-modal data. Reliability Engineering & System Safety, 234, 109136, (2023).
64
Bundesministerium für Digitales und Verkehr, (2021), https://bmdv.bund.de/DE/Themen/Mobili- taet/Schiene/Sicherheit-Schienenverkehr/sicherheit-schienenverkehr.html.
65
Pawlik, M. Rail Transport Systems Safety, Security and Cybersecurity Functional Integrity Levels. In: Siergiejczyk, M., Krzykowska, K. (eds) Research Methods and Solutions to Current Transport Problems. Ad- vances in Intelligent Systems and Computing. Springer (2020), p. 317.
66
Fourie, D. & Malan, C. Can Public Procurement Requirements for Railway Transport Promote Economic and Social Sustainability in South Africa? Sustainability, 13(21), 11923, (2021), p. 3 – 6.
67
IEA, The Future of Rail – Opportunities for energy and the environment. International Energy Agency (2019), p. 104 – 126.
68
Zitricky, V., Cerna, L. & Abramovic B. The Proposal for the Allocation of Capacity for International Railway Transport. Procedia Engineering, 192, 994-999 (2017), p. 995 – 997.
69
Veen-Groot, D. B. & Nijkamp, P. Globalisation, transport and the environment: new perspectives for ecologi- cal economics. Ecological Economics, 31(3), 331-346 (1999), p. 332 – 335.
70
IEA, The Future of Rail – Opportunities for energy and the environment. International Energy Agency (2019), p. 34 – 35.
71
Wenner, F. & Moser, J. Welche Regionen profitieren von der Bahnanbindung? Deutschland 1990-2030 – Eine kurze Reise mit Karten und Diagrammen, (2020), p. 6.
72
Böttger, C. Umbau der Bahn. Ifo Schnelldienst, 76(6), 6-9 (2023), p. 6.
73
Gewessler, L. Nachhaltigkeit Zentrales Anliegen des Klimaschutzministeriums. Nachhaltigkeitsrecht, 1(1), 6-13 (2021), p. 6.
74
Rehme, M. et al. Smart Rail Bewertung von Innovationsideen und Management von Innovationsbarrieren am Beispiel integrierter Mobilitätsketten für ländliche Räume. In: Proff, H. (eds) Neue Dimensionen der Mobilität. Springer Gabler, Wiesbaden. (2020), p. 112 – 114.
75
Eckhardt, C. E., Nachhaltige Mobilität – mit Innovationen im Personenverkehr zum Erfolg. Ifo Schnelldienst, 76(6), 9-12 (2023), p. 11 – 12.

1
Pyrgidis, Christos. Railway Transportation Systems; Taylor & Francis Group, (2022), p. 1.
2
Pyrgidis, Christos. Railway Transportation Systems; Taylor & Francis Group, (2022), p. 22.
3
Janson, Matthias. So viel Treibhausgas emittieren Flugzeug, Bahn & Co, (2023) https://de.statista.com/info-grafik/18952/treibhausgasemissionen-nach-verkehrsmitteln.
4
ABB. Transporteffizienz steigern. Vorteile und Chancen des beschleunigten Übergangs zu nachhaltigem Verkehr, (2021) https://www.energyefficiencymovement.com/wp-content/uploads/2021/10/ABB_EE_WhitePa- per_Transportation_final_DE.pdf.
5
Allianz pro Schiene. Höhe der Treibhausgas-Emissionen im deutschen Güterverkehr nach Verkehrsträgern im Jahr 2019, (2021), https://de.statista.com/statistik/daten/studie/881600/umfrage/co2-emissionen-im-deutschen- gueterverkehr-nach-verkehrsmitteln/.
6
Zak, Jolanta et al.. The role of railway transport in designing a proecological transport system, Computers in Railways XIV Special Contributions. 15-26 (2015).
7
Pawlik, Marek. Analyse of the challenges for safe transition individual intraoperable railway systems to the sin- gle European interoperable railway system. Archives of civil engineering, 62(4), 169-180 (2016), p. 174-175.
8
Pufé, Iris. Nachhaltigkeit. Stuttgart: UTB. p.101.
9
Gyamfi, Bright et al. Beyond the environmental Kuznets curve: Do combined impacts of air transport and rail transport matter for environmental sustainability amidst energy use in E7 economies?. Environment, Develop- ment and Sustainability. 24. 11852-11870 (2022), p. 11853.
10
Allianz pro Schiene. Höhe der Treibhausgas-Emissionen im deutschen Personenfernverkehr nach Verkehrsträ- gern im Jahr 2019 (in Gramm pro Personenkilometer). In Statista. (2021) https://de-statista-com.proxy02a.bis.uni-oldenburg.de/statistik/daten/studie/322971/umfrage/hoehe-der-schadstoffemissionen- durch-fernverkehr/
11
Gyamfi, Bright et al. Beyond the environmental Kuznets curve: Do combined impacts of air transport and rail transport matter for environmental sustainability amidst energy use in E7 economies?. Environment, Develop- ment and Sustainability. 24. 11852-11870 (2022), p. 11863.
12
Pufé, Iris. Nachhaltigkeit. Stuttgart: UTB. p.102.
13
Ren, Xiaohong et al. Impact of high-speed rail on social equity in China: Evidence from a mode choice sur- vey. Transportation Research Part A. 138 (2020). 422-441. p. 423
14
Ren, Xiaohong et al. Impact of high-speed rail on social equity in China: Evidence from a mode choice sur- vey. Transportation Research Part A. 138 (2020). 422-441. p. 424
15
Statista Research Department. Das 9€ Ticket, (2023). https://de-statista-com.proxy02a.bis.uni-olden- burg.de/themen/9462/9-euro-ticket/#topicOverview
16
Naumann, Anja, Grippenkoven, Jan. Bahnarbeitsplätze im Wandel. EIK – Eisenbahn Ingenieur Kompendium. DVV Media Group. ISSN 2511-9982 (2023). 296-302. p. 296.
17
Naumann, Anja, Grippenkoven, Jan. Bahnarbeitsplätze im Wandel. EIK – Eisenbahn Ingenieur Kompendium. DVV Media Group. ISSN 2511-9982 (2023). 296-302. p. 297-298.
18
Wang, Luqi et al. The Impacts of Transportation Infrastructure on Sustainable Development: Emerging Trends and Challenges. International Journal of Environmental Research and Public Health. 15(1172). 1-24 (2018). p. 3.
19
RSSB. Sustainable Rail, (2021) https://www.rssb.co.uk/who-we-are/about-us/sustainable-rail.
20
RSSB. Sustainable Rail Strategy, (2022) https://www.rssb.co.uk/sustainability/sustainable-rail-strat-egy#:~:text=This%20SRS%20Prototype%20is%20a%20vital%20stepping%20stone,is%20re-quired%20if%20ambitions%20are%20to%20be%20realised.
21
World Business Council for Sustainable Development. World Resources Institute: The Greenhouse Gas Proto- col. Accounting and Reporting Standard. Hg. v. W. R.I. WBCSD, (2004), p. 27-29.
22
Zawadski, Annika et al. Riding the Rails to Sustainability. Boston Consulting Group, (2022), p. 5, https://www.bcg.com/publications/2022/riding-the-rails-to-the-future-of-sustainability.
23
Zawadski, Annika et al. Riding the Rails to Sustainability. Boston Consulting Group, (2022), p. 6-14, https://www.bcg.com/publications/2022/riding-the-rails-to-the-future-of-sustainability.
24
High Speed Rail Development Worldwide. Environmental and Energy Study Institute, (2018) https://www.eesi.org/papers/view/fact-sheet-high-speed-rail-development-worldwide.
25
Islam, Dewan. Prospects for European sustainable rail freight transport during economic austerity. Bench- marking: An International Journal vol. 25 iss. 8. 2783-2805 (2018) p. 2796
26
Tunnicliffe, Andrew. Will California ever get its high-speed rail? Railway Technology, (2023), https://www.railway-technology.com/features/will-california-ever-get-its-high-speed-rail/?cf-view.
27
Watson, Inara, Ali, Amer & Bayyati, Ali. Sustainability of high-speed rail: a comparative study. Proceedings of the Institution of Civil Engineers – Transport, (2018).
28
Bueno, Gorka, Hoyos, David & Capellan-Perez, Inigo. Evaluating the environmental performance of the high speed rail project in the Basque Country, Spain. Research in Transportation Economics vol. 62, 44-56 (2017).
29
Yuanhui Li & Check-Teck Foo. Towards sustainability in the high-speed railway industry: modeling of cases from China. Chinese Management Studies, 8(4), 624 – 641 (2014).
30
Breuer, J.L.; Scholten, J.; Koj, J.C.; Schorn, F.; Fiebrandt, M.; Samsun, R.C.; Albus, R.; Görner, K.; Stolten, D.; Peters, R. An Overview of Promising Alternative Fuels for Road, Rail, Air, and Inland Waterway Transport in Germany. Energies, 15 (4), 1443 (2022), p. 32, 47.
31
Röpcke, T., Windt, A. Umstellung liniengebundener Fahrzeuge auf alternative Antriebstechnologien. Sonderprojekte ATZ/MTZ 24 (Suppl 2), 36–39 (2019), p. 36 – 38.
32
Mitrofanov, S.V.; Kiryanova, N.G.; Gorlova, A.M. Stationary Hybrid Renewable Energy Systems for Railway Electrification: A Review. Energies, 14, 5946 (2021), p. 16.
33
Zweig, BW., Stephan, A.. Energieversorgung elektrischer Bahnen. In: Fendrich, L., Fengler, W. (eds.) Hand- buch Eisenbahninfrastruktur. Springer Vieweg, Berlin, Heidelberg (2019), P. 724 – 727.
34
Deutsche Bahn AG, Wir laden Züge elektrisch auf. https://nachhaltigkeit.deutschebahn.com/de/massnah- men/akkuzuege (2023).
35
Lee, K., Jung, H. An improvement of manufacturing process using 3D printing technology for overhead line components on railway electrification. J. Electr. Eng. Technol., 17, 3085–3091 (2022), p. 3085.
36
Zenith F, Isaac R, Hoffrichter A, Thomassen MS, Møller-Holst S. Techno-economic analysis of freight rail- way electrification by overhead line, hydrogen and batteries: Case studies in Norway and USA. Journal of Rail and Rapid Transit, 234 (7), 791-802 (2020), p. 802.
37
Popovich, N.D., Rajagopal, D., Tasar, E. et al. Economic, environmental and grid-resilience benefits of con- verting diesel trains to battery-electric. Nat Energy, 6, 1017–1025 (2021), p. 1017 – 1020.
38
S. M. Mousavi Gazafrudi, A. Tabakhpour Langerudy, E. F. Fuchs and K. Al-Haddad, Power Quality Issues in Railway Electrification: A Comprehensive Perspective. IEEE Transactions on Industrial Electronics, 62 (5), 3081 – 3090 (2015), p.3081 – 3082.
39
Mitrofanov, S.V.; Kiryanova, N.G.; Gorlova, A.M. Stationary Hybrid Renewable Energy Systems for Railway Electrification: A Review. Energies, 14, 5946 (2021), p. 8 & p. 14 – 15.
40
Breuer, J.L.; Scholten, J.; Koj, J.C.; Schorn, F.; Fiebrandt, M.; Samsun, R.C.; Albus, R.; Görner, K.; Stolten, D.; Peters, R. An Overview of Promising Alternative Fuels for Road, Rail, Air, and Inland Waterway Transport in Germany. Energies, 15 (4), 1443 (2022), p. 30 – 31.
41
Zenith F, Isaac R, Hoffrichter A, Thomassen MS, Møller-Holst S. Techno-economic analysis of freight rail- way electrification by overhead line, hydrogen and batteries: Case studies in Norway and USA. Journal of Rail and Rapid Transit, 234 (7), 791-802 (2020), p. 798 – 800.
42
Mitrofanov, S.V.; Kiryanova, N.G.; Gorlova, A.M. Stationary Hybrid Renewable Energy Systems for Railway Electrification: A Review. Energies, 14, 5946 (2021), p. 17
43
Kruse, M., Wedemeier, J. Potenzial grüner Wasserstoff: langer Weg der Entwicklung, kurze Zeit bis zur Um- setzung. Wirtschaftsdienst 101, 26–32 (2021), p. 1 – 5.
44
Atteridge WJ, Lloyd SA. Thoughts on use of hydrogen to power railway trains. Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy. 235(2), 306-316 (2021), p. 306 – 308.
45
Zenith F, Isaac R, Hoffrichter A, Thomassen MS, Møller-Holst S. Techno-economic analysis of freight rail- way electrification by overhead line, hydrogen and batteries: Case studies in Norway and USA. Journal of Rail and Rapid Transit, 234 (7), 791-802 (2020), p. 801.
46
Edwards, J.R.; Mechitov, K.A.; Germoglio Barbosa, I.; de O. Lima, A.; Spencer, B.F., Jr.; Tutumluer, E.; Dersch, M.S. A Roadmap for Sustainable Smart Track—Wireless Continuous Monitoring of Railway Track Condition. Sustainability, 13, 7456, (2021), p. 1 – 2, 12 – 13.
47
Ferrante, C., Bianchini Ciampoli, L., Benedetto, A. et al. Non-destructive technologies for sustainable assess- ment and monitoring of railway infrastructure: a focus on GPR and InSAR methods. Environmental Earth Sci- ence 80 (806), (2021), p. 1 – 2, 17.
48
Gonzalez-Jimenez D, Del-Olmo J, Poza J, Garramiola F, Madina P. Data-Driven Low-Frequency Oscillation Event Detection Strategy for Railway Electrification Networks. Sensors23 (254), (2023), p. 1 – 3.
49
Kaewunruen S, Peng S, Phil-Ebosie O. Digital Twin Aided Sustainability and Vulnerability Audit for Subway Stations. Sustainability, 12(19), (2020), p. 1 – 2, 14.
50
Haodong Yin, Jianjun Wu, Zhiyuan Liu, Xin Yang, Yunchao Qu, Huijun Sun. Optimizing the release of pas- senger flow guidance information in urban rail transit network via agent-based simulation. Applied Mathemati- cal Modelling, 72, 337-355 (2019), p. 337 – 340, 353 – 354.
51
Cohen, J. M., Barron, A. S., Anderson, R. J., & Graham, D. J.. Impacts of Unattended Train Operations on Productivity and Efficiency in Metropolitan Railways. Transportation Research Record, 2534(1), 75 – 83 (2015), p. 75 – 76, 78 – 82.
52
United Nations. Sustainability. https://www.un.org/en/academic-impact/sustainability (1987).
53
Ivic, A., Saviolidis N. A. & Johannsdottir, L. Drivers Of Sustainability Practices And Contributions To Sus- tainable Development Evident In Sustainability Reports Of European Mining Companies (2021) p. 12 – 19.
54
Duarte, F. Barriers to Sustainability: An Exploratory Study on Perspectives from Brazilian Organizations. Sus- tainable Development 23 (6), 425-434 (2015), p. 425 – 427.
55
Smith, R. A. Railways: How They May Contribute To A Sustainable Future. Proceedings of The Institution of Mechanical Engineers Part F-journal of Rail and Rapid Transit 217 (4), 243-248 (2003), p. 245.
56
Smith, R. A. Railways: How They May Contribute To A Sustainable Future. Proceedings of The Institution of Mechanical Engineers Part F-journal of Rail and Rapid Transit 217 (4), 243-248 (2003), p. 246.
57
IEA, The Future of Rail – Opportunities for energy and the environment. International Energy Agency (2019), p. 97.
58
IEA, The Future of Rail – Opportunities for energy and the environment. International Energy Agency (2019), p. 100 – 101.
59
Givone, M., Brand, C. & Watkiss, P. Are Railways Climate Friendly? Built Environment 35 (1), 70-86 (2009), p. 70 – 76.
60
Moradi, S., Ahadi, H. R. & Sierpinski, G. Sustainable Management of Railway Companies Amid Inflation and Reduced Government Subsidies: A System Dynamics Approach. Sustainability 15 (4), 111176, (2023), p. 2 – 3.
61
Wang, Y., De Blois, S. & Oldknow, K. D. Incentivized decarbonization through safer and more efficient heavy haul operations. Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit, (2023).
62
Wang, Y. et al. The Impact of Service Quality and Customer Satisfaction on Reuse Intention in Urban Rail Transit in Tianjin, China. SAGE Open 10(1), (2020), p. 1.
63
Dongyang, Y. et al. A railway accident prevention method based on reinforcement learning – Active preven- tive strategy by multi-modal data. Reliability Engineering & System Safety, 234, 109136, (2023).
64
Bundesministerium für Digitales und Verkehr, (2021), https://bmdv.bund.de/DE/Themen/Mobili- taet/Schiene/Sicherheit-Schienenverkehr/sicherheit-schienenverkehr.html.
65
Pawlik, M. Rail Transport Systems Safety, Security and Cybersecurity Functional Integrity Levels. In: Siergiejczyk, M., Krzykowska, K. (eds) Research Methods and Solutions to Current Transport Problems. Ad- vances in Intelligent Systems and Computing. Springer (2020), p. 317.
66
Fourie, D. & Malan, C. Can Public Procurement Requirements for Railway Transport Promote Economic and Social Sustainability in South Africa? Sustainability, 13(21), 11923, (2021), p. 3 – 6.
67
IEA, The Future of Rail – Opportunities for energy and the environment. International Energy Agency (2019), p. 104 – 126.
68
Zitricky, V., Cerna, L. & Abramovic B. The Proposal for the Allocation of Capacity for International Railway Transport. Procedia Engineering, 192, 994-999 (2017), p. 995 – 997.
69
Veen-Groot, D. B. & Nijkamp, P. Globalisation, transport and the environment: new perspectives for ecologi- cal economics. Ecological Economics, 31(3), 331-346 (1999), p. 332 – 335.
70
IEA, The Future of Rail – Opportunities for energy and the environment. International Energy Agency (2019), p. 34 – 35.
71
Wenner, F. & Moser, J. Welche Regionen profitieren von der Bahnanbindung? Deutschland 1990-2030 – Eine kurze Reise mit Karten und Diagrammen, (2020), p. 6.
72
Böttger, C. Umbau der Bahn. Ifo Schnelldienst, 76(6), 6-9 (2023), p. 6.
73
Gewessler, L. Nachhaltigkeit Zentrales Anliegen des Klimaschutzministeriums. Nachhaltigkeitsrecht, 1(1), 6-13 (2021), p. 6.
74
Rehme, M. et al. Smart Rail Bewertung von Innovationsideen und Management von Innovationsbarrieren am Beispiel integrierter Mobilitätsketten für ländliche Räume. In: Proff, H. (eds) Neue Dimensionen der Mobilität. Springer Gabler, Wiesbaden. (2020), p. 112 – 114.
75
Eckhardt, C. E., Nachhaltige Mobilität – mit Innovationen im Personenverkehr zum Erfolg. Ifo Schnelldienst, 76(6), 9-12 (2023), p. 11 – 12.