Energy efficiency and greenhouse gas emissions vary among different modes of transportation. The field of life-cycle assessment (LCA) has been formed, in part, to enable direct comparisons among transportation modes. In this video, life-cycle assessment is used to compare the energy efficiency and greenhouse gas impacts of a diesel-powered low-speed train with an electrically powered high-speed train. In order to make the comparison, there's a disscussion of different types of trains, describing life-cycle assessment methods, and explaining greenhouse gas emissions accounting. The results demonstrate the importance of considering energy and environmental impacts when choosing transportation. The calculations in this video are based off of numerical data gathered between 2009 and 2012.