Abstract
In 2007, the United Nations (UN) published a comprehensive report on "Climate Change," which
highlighted the significant impact of greenhouse gases (GHGs) on climate variations and the
alarming rise in global temperatures. In response, nations were urged to devise action plans aimed at
reducing the emissions of these harmful gases. Carbon dioxide (CO2) emerged as the primary
greenhouse gas, with transportation systems accounting for approximately 25% of total global
emissions, primarily driven by private vehicle use. Projections indicate that by 2050, energy
consumption in transport systems will double, further exacerbating gas emissions unless effective
mitigation strategies are implemented. Global environmental awareness has grown, prompting
governments to enact policies designed to lower GHG emissions. Several cities have established
quantitative reduction targets. For instance, London aims for a 60% reduction in transport sector
emissions by 2025, relative to 1999 levels. In Brazil, the state of Rio de Janeiro set a target for a 30%
reduction in transport-related GHG emissions by 2030, based on 2010 levels, through decree 43.216
of September 30, 2011. A well-functioning public transport system can effectively address this issue
by reducing reliance on private vehicles. Metro rail systems are recognized for their relatively low
CO2 emissions compared to other motorized transport modes. However, when considering total
emissions – including those from infrastructure construction – it is crucial to assess whether metro
rail systems remain the most viable option in terms of CO2 emissions. This paper aims to conduct a
Life Cycle Assessment (LCA) of metro rail systems, focusing on estimating the CO2 emissions
associated with each life cycle stage throughout the system’s operational life. Additionally, it will
examine the conditions that support or challenge the implementation of such systems. Section 1 serves
as the introduction, outlining the study’s context and objectives. Section 2 presents a diagnosis of
LCA in metro rail systems, including related standards and assessment tools. Section 3 analyzes
emission results from existing studies on metro rail systems worldwide, discussing the conditions that
justify their implementation.
Keywords: Life Cycle Assessment, metro rail systems, CO2 emissions, greenhouse gases, public
transportation, sustainable transport, infrastructure emissions

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1. Local strategy for climate change. Almada Municipal Energy Agency. 2005. Available at http://www.ageneal.pt/DirEscrita/upload/docs/ELAC_3.pdf.
2. Akerman J. The role of high-speed rail in mitigating climate change – The Swedish case Europabanan from a life cycle perspective. Transp Res Part D Transp Environ. 2011;16:208–217. doi: 10.1016/j.trd.2010.12.004.
3. Chang B, Kendal A. Life cycle greenhouse gas assessment of infrastructure construction for California’s high-speed rail system. Transp Res Part D Transp Environ. 2011;16:429–434. doi: 10.1016/j.trd.2011.04.004.
4. Chester M. Life-cycle environmental inventory of passenger transportation in the United States [dissertation]. Berkeley (CA): University of California; 2008. Available at http://escholarship.org/uc/item/7n29n303.
5. Chester M, Horvath A. Life-cycle energy and emissions inventory for motorcycles, diesel, automobiles, school buses and metropolitan rails. 2009a. Available at http://escholarship.org/uc/item/6z37f2jr.pdf.
6. Chester M, Horvath A. Environmental assessment of passenger transportation should include infrastructure and supply chains. Environ Res Lett. 2009b;4(2):024008. doi: 10.1088/1748-9326/4/2/024008.
7. Energy costs, renewables and CO2 emissions Nova phase 10 case study. Community of Metros. 2008.
8. Key performance indicators – Annual report (2011 data). Community of Metros. 2012.
9. Empresa de Pesquisa Energética (EPE). (2012). National Energy Balance. Available at https://ben.epe.gov.br/downloads/Resultados_Pre_BEN_2012.pdf.
10. Grossrieder C. Life-cycle assessment of future high-speed rail in Norway [dissertation]. Trondheim: Norwegian University of Science and Technology; 2011. Available at http://ntnu.diva-portal.org/smash/get/diva2:441342/FULLTEXT01.pdf.
11. International Energy Agency (IEA). (2009). Transport, energy and CO2. Available at http://www.iea.org/publications/freepublications/publication/transport2009.pdf.
12. International Organization for Standardization (ISO). (2009). ISO 14040:2009 environmental management – life cycle assessment – principles and framework.
13. Instituto de Pesquisa Econômica Aplicada (IPEA). (2011). Relative pollutant emissions from motorized passenger transport in large Brazilian urban centers. Available at http://desafios2.ipea.gov.br/portal/images/stories/PDFs/TDs/td_1606.pdf.
14. Kato H, Osada M, Shibahara N, Hayashi Y. A life cycle assessment for evaluating environmental impacts of inter-regional high-speed mass transit projects. J East Asia Soc Transp Stud. 2005;6:3211–3224.
15. Kiani M, Parry T, Ceney H. Environmental life-cycle assessment of railway track beds. Eng Sustain. 2008;161:135-42. doi: 10.1680/ensu.2008.161.2.135.
16. London Underground. London Underground carbon footprint. 2009. Available at http://www.tfl.gov.uk/assets/downloads/corporate/london-underground-carbon-footprint-2008.pdf.
17. Metro Bilbao. Carbon footprint. 2012. Available at http://metro-bilbao.cms.nuatt.es/system/attachments/4f6b1b0afc7a7b3629000001/original/huella%20de%20carbono.pdf?2012-03-22T12:28:58+00:00.
18. Metro de Lisboa. 2010 Sustainability report. 2011. Available at http://www.metrolisboa.pt/wp-content/uploads/Relat%C3%B3rio-de-sustentabilidade2010.pdf.
19. Milford R, Allwood J. Assessing the CO2 impact of current and future rail track in the UK. Transp Res Part D Transp Environ. 2010;15:61–72. doi: 10.1016/j.trd.2009.09.003.
20. Miliutenko S. Life cycle impacts of road infrastructure – Assessment of energy use and greenhouse gas emissions [dissertation]. Stockholm: KTH Royal Institute of Technology; 2012. Available at http://www.diva-portal.org/smash/get/diva2:503911/FULLTEXT01.
21. Morita Y, Yamasaki T, Shimizu K, Kato H, Shibahara N. A study on greenhouse gas emission of urban railway projects in Tokyo metropolitan area. Proc East Asia Soc Transp Stud. 2011;8.
22. Metropolitan Transport Authority (MTA). Renewable energy task report. 2008. Available at http://www.mta.info/sustainability/pdf/MTA%20Renewable%20Energy%20Report%2010%2029%2008.pdf.
23. Metropolitan Transport Authority (MTA). Sustainability report. 2012. Available at http://www.mta.info/sustainability/pdf/2012Report.pdf.
24. Network Rail. Comparing environmental impact of conventional and high-speed rail. London; 2009.
25. City of New York. Inventory of New York City greenhouse gas emissions. 2011. Available at http://nytelecom.vo.llnwd.net/o15/agencies/planyc2030/pdf/planyc_2011_planyc_full_report.pdf.
26. Silva CBP, Neto RCS, Aragão WA. Greenhouse gas emissions associated with the life cycle of a metro line: Case study of the São Paulo Metro Line 5 – LILÁS. 2017. Available at http://www.aeamesp.org.br/wp-content/uploads/2017/09/artigo_GEE_LINHA5.pdf.
27. Stripple H, Uppenberg S. Life cycle assessment of railways and rail transports. IVL Swedish Environmental Research Institute, Stockholm. 2010. Available at http://www.ivl.se/download/18.7df4c4e812d2da6a416800072122/B1943.pdf.
28. Svensson N, Eklund M. Screening of environmental pressure from products in the Swedish railway infrastructure: Implications for strategic environmental management. Resour Conserv Recycl. 2007;52:248–265. doi: 10.1016/j.resconrec.2007.03.006.
29. Westin J, Kageson P. Can high-speed rail offset its embedded emissions? Transp Res Part D Transp Environ. 2012;17:1–7. doi: 10.1016/j.trd.2011.09.006.

Abstract
In 2007, the United Nations (UN) published a comprehensive report on "Climate Change," which
highlighted the significant impact of greenhouse gases (GHGs) on climate variations and the
alarming rise in global temperatures. In response, nations were urged to devise action plans aimed at
reducing the emissions of these harmful gases. Carbon dioxide (CO2) emerged as the primary
greenhouse gas, with transportation systems accounting for approximately 25% of total global
emissions, primarily driven by private vehicle use. Projections indicate that by 2050, energy
consumption in transport systems will double, further exacerbating gas emissions unless effective
mitigation strategies are implemented. Global environmental awareness has grown, prompting
governments to enact policies designed to lower GHG emissions. Several cities have established
quantitative reduction targets. For instance, London aims for a 60% reduction in transport sector
emissions by 2025, relative to 1999 levels. In Brazil, the state of Rio de Janeiro set a target for a 30%
reduction in transport-related GHG emissions by 2030, based on 2010 levels, through decree 43.216
of September 30, 2011. A well-functioning public transport system can effectively address this issue
by reducing reliance on private vehicles. Metro rail systems are recognized for their relatively low
CO2 emissions compared to other motorized transport modes. However, when considering total
emissions – including those from infrastructure construction – it is crucial to assess whether metro
rail systems remain the most viable option in terms of CO2 emissions. This paper aims to conduct a
Life Cycle Assessment (LCA) of metro rail systems, focusing on estimating the CO2 emissions
associated with each life cycle stage throughout the system’s operational life. Additionally, it will
examine the conditions that support or challenge the implementation of such systems. Section 1 serves
as the introduction, outlining the study’s context and objectives. Section 2 presents a diagnosis of
LCA in metro rail systems, including related standards and assessment tools. Section 3 analyzes
emission results from existing studies on metro rail systems worldwide, discussing the conditions that
justify their implementation.
Keywords: Life Cycle Assessment, metro rail systems, CO2 emissions, greenhouse gases, public
transportation, sustainable transport, infrastructure emissions

🔒 This is a subscription article

Full text is available to subscribers and institutional members. Please choose an option below to access it.

1. Local strategy for climate change. Almada Municipal Energy Agency. 2005. Available at http://www.ageneal.pt/DirEscrita/upload/docs/ELAC_3.pdf.
2. Akerman J. The role of high-speed rail in mitigating climate change – The Swedish case Europabanan from a life cycle perspective. Transp Res Part D Transp Environ. 2011;16:208–217. doi: 10.1016/j.trd.2010.12.004.
3. Chang B, Kendal A. Life cycle greenhouse gas assessment of infrastructure construction for California’s high-speed rail system. Transp Res Part D Transp Environ. 2011;16:429–434. doi: 10.1016/j.trd.2011.04.004.
4. Chester M. Life-cycle environmental inventory of passenger transportation in the United States [dissertation]. Berkeley (CA): University of California; 2008. Available at http://escholarship.org/uc/item/7n29n303.
5. Chester M, Horvath A. Life-cycle energy and emissions inventory for motorcycles, diesel, automobiles, school buses and metropolitan rails. 2009a. Available at http://escholarship.org/uc/item/6z37f2jr.pdf.
6. Chester M, Horvath A. Environmental assessment of passenger transportation should include infrastructure and supply chains. Environ Res Lett. 2009b;4(2):024008. doi: 10.1088/1748-9326/4/2/024008.
7. Energy costs, renewables and CO2 emissions Nova phase 10 case study. Community of Metros. 2008.
8. Key performance indicators – Annual report (2011 data). Community of Metros. 2012.
9. Empresa de Pesquisa Energética (EPE). (2012). National Energy Balance. Available at https://ben.epe.gov.br/downloads/Resultados_Pre_BEN_2012.pdf.
10. Grossrieder C. Life-cycle assessment of future high-speed rail in Norway [dissertation]. Trondheim: Norwegian University of Science and Technology; 2011. Available at http://ntnu.diva-portal.org/smash/get/diva2:441342/FULLTEXT01.pdf.
11. International Energy Agency (IEA). (2009). Transport, energy and CO2. Available at http://www.iea.org/publications/freepublications/publication/transport2009.pdf.
12. International Organization for Standardization (ISO). (2009). ISO 14040:2009 environmental management – life cycle assessment – principles and framework.
13. Instituto de Pesquisa Econômica Aplicada (IPEA). (2011). Relative pollutant emissions from motorized passenger transport in large Brazilian urban centers. Available at http://desafios2.ipea.gov.br/portal/images/stories/PDFs/TDs/td_1606.pdf.
14. Kato H, Osada M, Shibahara N, Hayashi Y. A life cycle assessment for evaluating environmental impacts of inter-regional high-speed mass transit projects. J East Asia Soc Transp Stud. 2005;6:3211–3224.
15. Kiani M, Parry T, Ceney H. Environmental life-cycle assessment of railway track beds. Eng Sustain. 2008;161:135-42. doi: 10.1680/ensu.2008.161.2.135.
16. London Underground. London Underground carbon footprint. 2009. Available at http://www.tfl.gov.uk/assets/downloads/corporate/london-underground-carbon-footprint-2008.pdf.
17. Metro Bilbao. Carbon footprint. 2012. Available at http://metro-bilbao.cms.nuatt.es/system/attachments/4f6b1b0afc7a7b3629000001/original/huella%20de%20carbono.pdf?2012-03-22T12:28:58+00:00.
18. Metro de Lisboa. 2010 Sustainability report. 2011. Available at http://www.metrolisboa.pt/wp-content/uploads/Relat%C3%B3rio-de-sustentabilidade2010.pdf.
19. Milford R, Allwood J. Assessing the CO2 impact of current and future rail track in the UK. Transp Res Part D Transp Environ. 2010;15:61–72. doi: 10.1016/j.trd.2009.09.003.
20. Miliutenko S. Life cycle impacts of road infrastructure – Assessment of energy use and greenhouse gas emissions [dissertation]. Stockholm: KTH Royal Institute of Technology; 2012. Available at http://www.diva-portal.org/smash/get/diva2:503911/FULLTEXT01.
21. Morita Y, Yamasaki T, Shimizu K, Kato H, Shibahara N. A study on greenhouse gas emission of urban railway projects in Tokyo metropolitan area. Proc East Asia Soc Transp Stud. 2011;8.
22. Metropolitan Transport Authority (MTA). Renewable energy task report. 2008. Available at http://www.mta.info/sustainability/pdf/MTA%20Renewable%20Energy%20Report%2010%2029%2008.pdf.
23. Metropolitan Transport Authority (MTA). Sustainability report. 2012. Available at http://www.mta.info/sustainability/pdf/2012Report.pdf.
24. Network Rail. Comparing environmental impact of conventional and high-speed rail. London; 2009.
25. City of New York. Inventory of New York City greenhouse gas emissions. 2011. Available at http://nytelecom.vo.llnwd.net/o15/agencies/planyc2030/pdf/planyc_2011_planyc_full_report.pdf.
26. Silva CBP, Neto RCS, Aragão WA. Greenhouse gas emissions associated with the life cycle of a metro line: Case study of the São Paulo Metro Line 5 – LILÁS. 2017. Available at http://www.aeamesp.org.br/wp-content/uploads/2017/09/artigo_GEE_LINHA5.pdf.
27. Stripple H, Uppenberg S. Life cycle assessment of railways and rail transports. IVL Swedish Environmental Research Institute, Stockholm. 2010. Available at http://www.ivl.se/download/18.7df4c4e812d2da6a416800072122/B1943.pdf.
28. Svensson N, Eklund M. Screening of environmental pressure from products in the Swedish railway infrastructure: Implications for strategic environmental management. Resour Conserv Recycl. 2007;52:248–265. doi: 10.1016/j.resconrec.2007.03.006.
29. Westin J, Kageson P. Can high-speed rail offset its embedded emissions? Transp Res Part D Transp Environ. 2012;17:1–7. doi: 10.1016/j.trd.2011.09.006.