Rail transport

Authors: Svea Poppen, Marieke Spellmeier, Polina Schröder, Henrik Sykora
Last updated: October 2nd 2023

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/h 2

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 energyefficient 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 pollution,5
per tonne-kilometre of freight, it is 15% compared to the lorry.
6 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.7
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,
8
so rail infrastructure expansion should be thought supranational.
5

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.9 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.10 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.11
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%.12 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.13

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.14 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.15 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.16 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.17 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.18 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.19

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.20
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.21

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 customers22 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 being 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.
23

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.24 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).25
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.26

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 beforehand
less connected regions indirectly with better connectivity and directly with the demand on
workforce and resources for construction of the infrastructure.27 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 Spain28
.
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 uncertain29). 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.30 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.31
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.32

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 systems33
.
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.34
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.35 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.
36 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 railcar37
.
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.
38 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 situation39
.
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.
40 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.
41
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.
42
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.43
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 are shown to provide significant reductions
in energy consumption compared to conventional diesel trains, with hydrogen trains consuming
about 49% less energy.
44 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.
45 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.
46
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.47
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.
48
A research study, in which the choice of propulsion technology is evaluated using countryspecific 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.49
3.3 Digital solutions and progress of intelligent systems
3.3.1 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.50 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.51
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.
52
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.
53
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.
3.3.2 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.54
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.
55 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.
56 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.57
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.58
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.59
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.60
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.61
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.62
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.63
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.64
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.65
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.66
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.67 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.68
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.69
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.70
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.71
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.72 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.73
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.74 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.75
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.76
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.77
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.78
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 2030.79
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.
80
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.