Life cycle assessment of high-speed rail: a case study in Portugal

PURPOSE: This study assesses the total life cycle environmental impact of the planned high-speed rail line from Lisbon to Porto, in Portugal. It includes the impact from the seven main processes of train manufacturing, train operation, train maintenance, train disposal, track construction, track operation and maintenance, and track disposal. METHODS: The SimaPro Life Cycle Assessment software is used and is based upon the ecoinvent v3 transport services process. The functional unit is 1 km of high-speed rail in Portugal for the processes and one passenger kilometer at the assembly level. Data was adjusted to reflect the Portuguese situation for electricity mix, domestic production of materials, transport distances, transport mode, and domestic emissions. In total, 50 different inputs were adjusted. The results were compared with transportation life cycle assessments for other countries. RESULTS AND DISCUSSION: The train operation process contributes the most to total environmental emissions: 69 % of the 684 million kilograms CO₂-eq., 76 % of the 4.9 million kilograms SO₂-eq. and 82 % of the 2.4 million kilograms PM₁₀-eq. Train manufacturing is the next largest contributor to total environmental emissions. The electricity mix plays a role in the amount of emissions, e.g., cleaner technology tends to have lower per passenger kilometer emissions. However, demand drives the amount of emissions per passenger kilometer. CONCLUSIONS: While the train operation process contributes the most to emissions, ignoring the other processes results in a substantial understatement of total environmental impact. For CO₂-eq. that means that 31 % of the total impact is ignored because the impact from construction, maintenance, and end of life is not included. Electricity mix and ridership levels have a very significant impact on emissions.