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    Calculating the carbon footprint of transportation

    In France, the transport sector is the biggest emitter of greenhouse gases, accounting for a third of all emissions. By transporting 10% of passengers for less than 1% of the sector's GHG emissions, rail is a solution for sustainable mobility.
    Updated on 24 January 20256-minute read

    The modal comparator

    The modal comparator is an essential tool for understanding the orders of magnitude between different modes of transport, and also for realizing the extent to which the choice of mobility has an impact on the environment.

    Carbon comparator for different modes of transport

    Comparateur carbone des différents modes de transport

    Table showing greenhouse gas emissions for a passenger traveling one kilometer in France, taking into account the impact of vehicle use, manufacture and maintenance.

    Comparison of data, in ascending order.

    • Train overall (8.3 grams of CO2e in total, including 6 grams of CO2e for use; 1.6 grams of CO2e for manufacture; 0.7 grams of CO2e for maintenance)
    • Electric car (49 grams of CO2e in total, including 7.2 grams of CO2e for use; 40 grams of CO2e for manufacturing; 1.4 grams of CO2e for maintenance)
    • Coach (71 grams of CO2e in total, including 66 grams of CO2e for use; 2.2 grams of CO2e for manufacture; 2.8 grams of CO2e for maintenance)
    • Thermal car (146 grams of CO2e in total, including 119 grams of CO2e for use; 24.7 grams of CO2e for manufacturing; 2.2 grams of CO2e for maintenance)
    • Aircraft (260 grams of CO2e in total, including 141 grams of CO2e for use; 0.4 grams of CO2e for manufacturing; 1.9 grams of CO2e for maintenance; 117 grams of CO2e for contrails and cirrus clouds).

    For road modes, the occupancy rate of 1.6 passengers is applied, corresponding to the mixed distance.

    For SNCF Voyageurs transport modes, 2023 values for use, manufacture and maintenance (maintenance-related emissions include only energy consumption used to maintain our trains).

    For other modes, ADEME Base Empreinte values for use and manufacturing, and Carbone 4 study values for SNCF for maintenance.

    In the interests of carbon education, we have chosen to display contrails and cirrus clouds as they produce a strong warming effect, translated into equivalent CO2. Aircraft are compared with long-distance trains only.

    SNCF Voyageurs transport carbon comparator

    In 2023, our trains in France avoided 14 million tonnes of CO2e, which would have been emitted by private cars.

    Comparateur carbone des transports SNCF Voyageurs

    Table showing the greenhouse gas emissions of a passenger traveling one kilometer in France, taking into account the impact of vehicle use, manufacture and maintenance.

    Comparison of data, in ascending order:

    • TGV (2.9 grams of CO2e in total, including 2 grams of CO2e for use; 0.6 grams of CO2e for manufacture; 0.3 grams of CO2e for maintenance)
    • INTERCITES (7 grams of CO2e in total, including 4.9 grams of CO2e for use; 0.5 grams of CO2e for manufacturing; 1.6 grams of CO2e for maintenance)
    • Train overall (8.3 grams of CO2e in total, including 6 grams of CO2e for use; 1.6 grams of CO2e for manufacturing; 0.7 grams of CO2e for maintenance).
    • TRANSILIEN (11.1 grams of CO2e in total, including 5.6 grams of CO2e for use; 4.3 grams of CO2e for manufacturing; 1.2 grams of CO2e for maintenance).
    • TER (24.4 grams of CO2e in total, including 19.4 grams of CO2e for use; 3.6 grams of CO2e for manufacturing; 1.4 grams of CO2e for maintenance)

    For SNCF Voyageurs transport modes, 2023 values for use, manufacturing and maintenance (maintenance emissions only include energy consumption used to maintain our trains).

    The SNCF Voyageurs 2024 Modal Comparator Note is an explanatory note that describes how SNCF Voyageurs compares different modes of transport, based on their CO2e emissions.

    Consult the Modal Comparator Note SNCF Voyageurs 2024

    Taking the train in France means an average 90% reduction in CO2e emissions for an equivalent journey by road or air*.


    * comparison on complete perimeters. Average figure. Air travel is only compared with the TGV.

    Regulations and our method

    TheCO2efootprint of a journey is calculated by multiplying the distance covered by the journey in question by the average quantity ofCO2eemitted per passenger per kilometer, depending on the mode of transport used.

    The reference document, updated annually, is the Info GES Methodological Note, which includes information on emissions factors by mode of transport, emissions accounting perimeters and regulatory information.

    Consult the Info GES methodological note

    Regulations require carriers, including SNCF Voyageurs, to provide passengers with CO2e data when they search for itineraries. This data can be consulted on the SNCF Voyageurs itineraries page of our website, after defining the route.

    The calculation method

    Explication visuel de la méthode de calcul

    This diagram explains how the carbon footprint of a passenger by type of train is calculated.

    On the upper part of the visual, pictograms showing a passenger and different trains with the following legend: GHG emissions of a passenger by type of train expressed in grams ofCO2e/Km.

    On the lower part of the visual, pictograms illustrate the formula leading to the above result. This is the ratio between the consumption of electricity, diesel or biodiesel required for the journey in question, multiplied by theCO2e emission factor of the electricity, diesel or biodiesel, and the number of passengers carried over the distance covered.

    This calculation is used each year to establish the average quantity ofCO2e emitted by each type of transport per passenger.

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    Header : © ©ShutterStock

    Carbon comparator for different modes of transport : © SNCF Voyageurs

    Infographic : © SNCF Voyageurs

    The calculation method : © SNCF Voyageurs

    Discover also : © Com à l'écran / ©SNCF Voyageurs / Alex Profit