Rail transportation plays a crucial role in reducing carbon emissions from the transportation system, making a significant contribution to environmental impact mitigation due to the efficiency of passenger and freight rail transportation. Accurate assessment of carbon emissions resulting from rail transit is essential to quantify the positive impact of this mode of transportation on overall urban transport emission reduction. Given that measuring carbon emissions throughout the lifecycle of rail transportation involves a wide array of factors, adopting a systematic framework for analyzing these aspects is crucial. This study conducts a comprehensive review of existing research related to carbon emissions in rail transportation and its mitigation. Initially, the distinct characteristics of carbon emissions associated with rail transportation are identified, along with the complexity involved in accurately measuring these emissions. Subsequently, a comparison and analysis are conducted regarding various models for measuring carbon emissions in rail transportation. Finally, the study examines some greenhouse gas emission measurement research within the railway system. Redirecting research efforts toward measuring carbon emissions in the rail transportation system is essential to help the development of robust and effective public policies. This measure will play a crucial role in emission reduction, climate change mitigation, and the promotion of more sustainable transportation. Furthermore, the identified results propose which LCA methodology offers a valuable framework improving the quality of railway transportation emissions for future generations.

In recent years, the issue of climate change has gained significant attention and become a focal point of discussion in various sectors of civil society. Governments, individuals, and scientists worldwide are increasingly concerned about the observed changes in climate patterns, often attributed to the rising levels of greenhouse gases. In this context, the main objective of this study is to assess the greenhouse gas emissions associated with the railway system in the state of Pernambuco, Brazil, and compare them with other national case studies, aiming to obtain greenhouse gas emission parameters specific to the railway system and propose mitigation models to address this environmental impact in the air. To achieve this goal, a comprehensive life cycle assessment (LCA) methodology was employed to examine the life cycle of the Pernambuco Metro. This involved conducting an inventory of resource inputs and emissions using actual observed data. Additionally, a comparative analysis of greenhouse gas emissions across different urban rail transport systems is presented to provide valuable contextual insights. The study findings reveal that the total greenhouse gas emissions from the Pernambuco rail system amount to 6170.54 t CO₂e. Considering a projected total service life of 50 years, the estimated greenhouse gas emissions for the entire life cycle of the system’s operation and maintenance reach 308,550 t CO₂e. The interdisciplinary nature of this research highlights the significance of studying the atmospheric effects of the Pernambuco railway system as a crucial parameter for designing strategies and technologies aimed at reducing air pollution within the region. Through quantifying and analyzing the greenhouse gas emissions of the Pernambuco rail system, this study provides valuable insights that contribute to addressing concerns related to climate change and promoting sustainable practices. It underscores the importance of developing effective strategies to mitigate air pollution and facilitates informed decision-making for the future of urban transportation systems.

A retrospective bibliometric analysis of the railway sector covering the 20-year period between 2002 and 2021 was carried out to better understand the characteristics of the railway research. The Scopus database contained 1918 articles published with the keywords “Rail System”. VOSviewer software was used to create network maps from each of the variables studied. The results showed a huge increase in the number of publications over this period—notably, work written by Zhang, Y.T., who was found to be the most productive author. Engineering was found to be the most studied subject area of knowledge; Transportation Research Record was the journal with the highest number of publications; and China was revealed to be the leading country regarding this research field, Southwest Jiaotong University being the leading institution in this topic. Finally, there was a lack of research on the environmental impact and sustainability of railway systems, an area that could be opened up for future study.

Recently, much research is being developed to improve sustainability in the transportation sector due to its impact on carbon dioxide (CO2) production, climate change, and fossil fuel resources. Railways in the world have started to use solar power assistance to improve sustainability in the transportation sector. The Brazilian Company of Urban Trains operates a Brazilian Light Rail Vehicle (BLRV) for passenger transportation in Brazil. This article is a study on the potential of environmental and economic benefits of the installation of solar panels in the BLRV roof, operated in the urban metropolitan area of João Pessoa, to provide assistance on electric load. The results show that the installation of photovoltaic system in the roofs of the total fleet of BLRVs operated in João Pessoa railway can save about R$ 800,000.00 and reduce the emission of 540 tons of CO2 in 10 years.

Water scarcity is a current problem in many parts of the planet and there is a worldwide concern about water availability to meet future water demand. In countries like Brazil, where most of the electricity is produced by hydroelectric power plants, water scarcity directly impacts energy production. The water–energy nexus is directly related and impacted by CO₂ emissions and its climate consequences, which calls to a broader approach: energy–carbon–water nexus. In this context, the Sustainable Water and Energy Consumption (SWEC) Program was developed to mitigate water and energy supply problems in a railway company in Brazil. The actions took place in four main areas: (a) users conscientization, (b) consumption diagnosis, (c) indicators for evaluating water and energy consumption, and (d) evaluation of implementing alternative cleaner water and energy sources. The per capita consumption of water and energy were reduced by 10% and 19%, respectively. Permanent results were achieved by the SWEC Program, such as the acquisition of two photovoltaic systems with a total capacity of 96.5 kWp. The investment made provided an average monthly reduction in energy consumption of 56% in 2022. This work contributed to the UN Agenda 2030 and the findings may help companies and industries, and other institutions, such as universities and schools, to improve their water and electricity consumption.

This article addresses the developing of a framework to obtain specific GHG emissions for the railway system and proposes mitigation strategies. To achieve this purpose, a comprehensive life cycle assessment (LCA) method was employed with input data from various sources to analyze the contribution of energy consumption and the emissions of the railway system. This paper included gathering data from an infrastructure operation and maintenance for detailed GHG emissions impact. This study also presents a comparative analysis of the GHG emissions in different urban railway transportation systems in Northeast Brazil, providing valuable contextual insights. As a result of the combination of total GHG emissions analysis from the states of the Northeast Brazil railway system, a total of 11,996.11 metric tons of CO₂ equivalent (tCO₂e) was estimated. The main line traction was a prominent source of the greenhouse gas footprint, especially for the diesel traction systems at Paraiba. The proposed framework shows that significant environmental benefits can be realized with proper decision-making to increase the number of passengers–kilometer transported by rail.