The life cycle energy demand and greenhouse gas emissions of high-capacity urban transport systems: A case study from Vienna's subway line U2

This article calculates the impact of three measures in order to reduce the global warming potential (GWP) and cumulative energy demand (CED) of Vienna's subway line U2. Results show that the increase of the train occupancy rate has the highest reduction impact (–30%/–30%), followed by new rolling stock (–26%/–34%), and a change in energy mix (–8%/–4%). The total reduction to be achieved with all measures combined is around –55% for GWP and CED, leading to a GWP of 91 g and 1.653 MJ per passenger kilometer traveled (PKT). With all these measures applied, the subway has lower GWP and CED than other modes of transport presented in the literature.