The article presents the essence of carbon footprint, defined as the sum of greenhouse gas emission, caused directly or indirectly by a person, organisation, product or event. Transport accounts for about 20% of global CO2 emission, ranking third after the energy sector (40%) and industry (25%). Therefore, in the era of railway development, especially high-speed rail, the issue of CO2 emission is of particular importance. High-speed vehicles require new, more durable materials, including composites, which generate a carbon footprint more than twice as large as that of steel. The carbon footprint of a rail vehicle is measured by the total amount of greenhouse gases emitted throughout its life cycle, generated by the product (i.e. rail vehicle) from the extraction of raw materials to the end-of-life stage of that product. The system boundaries used in the analysis of a product’s carbon footprint may vary, as is demonstrated in this article using the example of train carriages. The most comprehensive scope is ‘cradle-to-cradle’, as this model of product design encompasses all aspects of a product’s life. The study showed that the use of this model in the manufacture of new carriages decreases the carbon footprint four-fold. The paper presents collected and processed data regarding CO2 emission according to events, which indicates that the largest CO2 emissions occur within Scope 3 – other indirect emissions that concern activity throughout the entire value chain, e.g. transport products and processes, material production or even business travel, which account for 75%-85% of total emissions. CO2 emission are presented for different life-cycle stages of a vehicle and types of vehicles, as well as for construction materials used in the production of rail vehicles, including tram and metro carriages.