## 5 Conclusions  
The objective of this research was to calculate greenhouse gas (GHG) emissions throughout the entire life cycle of the railway system in Pernambuco, Brazil, using real observed data. Additionally, a comparative analysis was conducted to understand the level of emissions in the national context and provide guidance for future emission reduction efforts. This analysis also aimed to provide concrete data on environmental impact to policymakers, urban planners, and other stakeholders who seek to promote improvements in the railway system towards a sustainable railway system for future generations. The results showed that the total GHG emissions for the entire life cycle of the Pernambuco railway system, considering its construction length, amounted to 6170.54 metric tons of CO\({}_{2}\) equivalent (tCO\({}_{2}\)e). With a lifespan of 50 years, the projected emissions are estimated to reach 308,550 tCO\({}_{2}\)e.  
These findings offer valuable insights into the environmental impact of the railway system in Northeast Brazil, serving as a basis for identifying areas that need improvement and guiding future actions to reduce GHG emissions. However, due to the railway system's construction over 150 years ago, using the cargo transportation system of the federal railway network, there is a lack of concrete data on the quantity of construction materials used, making it impossible to calculate GHG emissions during the construction phase. The urban railway system in Pernambuco differs from the rest of the country as it combines trains powered by electricity and diesel. When compared to other national systems in the operation and maintenance phase, the traction emissions of the Pernambuco railway system were 4 g CO\({}_{2}\)e per passenger-kilometer traveled (PKT), which is competitive with the emissions of the Sao Paulo and Rio de Janeiro metros and the Rio de Janeiro railway. This is noteworthy considering the higher passenger volume in the latter systems. However, there is still significant potential for energy savings in the operation phase, particularly in stations and central buildings that could utilize solar energy. The northeastern region of Pernambuco, located close to the equator, receives abundant sunlight throughout the year, making solar energy a viable renewable option [55]. Implementing more efficient ventilation structures in metro stations and using energy-saving lighting solutions like LED lights can effectively reduce emissions from these stations [53]. For future research, it is recommended to conduct a more detailed comparative analysis that takes into account system boundaries, GHG accounting methods, and datasets from different case studies. This approach will provide a comprehensive and accurate understanding of emissions in diverse contexts. Furthermore, the development of a comprehensive estimation tool and a standardized benchmark applicable to various areas, equipment types, structures, and techniques would be highly beneficial. This would facilitate the collection and analysis of consistent and comparable data, enabling a more precise assessment of GHG emissions in different railway systems. This report provides, in addition, real-world experience and guidance from government and industry with years of experience in inventory. A comprehensive life cycle model of the entire railway system was developed. This report is meant as a complement to policymakers' efforts and provides, in addition, real-world experience and guidance from government and industry with years of experience in the charging space. Given the role of the railway system in Pernambuco's economy, especially as it relates to the distribution of goods and the provision of services, the Fuels Institute is dedicated to informing comprehensive discussions about the various policy options available to balance the various needs of the market while achieving significant reductions in transportation emissions.