Distance and CO2 ​

Every segment in the API carries the distance one passenger travels on it and the CO2 that passenger's trip emits, and this page explains how both figures are made.

What the figures are ​

distance (in km) and co2 (in kg) are fields on every Segment, wherever segments appear: timetable journeys from journeys, offers from journeyOffer and their parts, booked offer parts, and the segments of a JourneyOrderItem on an order.

• Per passenger. Each figure is for one passenger. Multiply by the number of passengers for a party.
• Per segment. A journey's total is the sum of its segments, and unknown if any segment is unknown.
• Null means unknown. A figure is null when we can't compute it, for example for a station we hold no coordinates for. It is never 0.
• Round for display. value is not rounded for display: distance comes to the meter and CO2 to the gram. Round it yourself.

Every figure is modeled, and no figure says how it was made. This page is the method to point travelers at.

Reading them from the API ​

Both fields are a Quantity: a value and the unit to print after it ("km" for distance, "kg" for CO2). Treat unit as a display symbol, not a closed set.

query JourneyOffer {
  journeyOffer(
    journeyId: "c0b652bb-ff2a-4dea-80f0-24f8f5333d36"
    passengers: [{ type: ADULT }]
  ) {
    itinerary {
      ... on SegmentCollection {
        segments {
          origin {
            name
          }
          destination {
            name
          }
          distance {
            value
            unit
          }
          co2 {
            value
            unit
          }
        }
      }
    }
  }
}

query JourneyOffer {
  journeyOffer(
    journeyId: "20080268-899b-4d1a-8aa1-9d63e89117e4"
    passengers: [{ type: ADULT }]
  ) {
    itinerary {
      ... on SegmentCollection {
        segments {
          origin {
            name
          }
          destination {
            name
          }
          distance {
            value
            unit
          }
          co2 {
            value
            unit
          }
        }
      }
    }
  }
}

{
  "data": {
    "journeyOffer": {
      "itinerary": [
        {
          "segments": [
            {
              "origin": { "name": "Stockholm Central" },
              "destination": { "name": "Göteborg Central" },
              "distance": { "value": 455.4, "unit": "km" },
              "co2": { "value": 1.157, "unit": "kg" }
            }
          ]
        }
      ]
    }
  }
}

{
  "data": {
    "journeyOffer": {
      "itinerary": [
        {
          "segments": [
            {
              "origin": { "name": "Stockholm Central" },
              "destination": { "name": "Göteborg Central" },
              "distance": { "value": 455.4, "unit": "km" },
              "co2": { "value": 1.157, "unit": "kg" }
            }
          ]
        }
      ]
    }
  }
}

Distance ​

A segment's distance is the track distance between its two stations, as reported by the timetable or the operator. When there is none, we estimate it from the straight lines between the train's stops × 1.13, or from the straight line between the two stations × 1.25 when the stops are unknown. The multipliers make up for the curves and detours of the track.

Once we have a track distance for a pair of stations, we keep it and reuse it in both directions, whichever operator sells the journey.

CO2 ​

Every factor is in g CO2e (CO2 equivalent) per passenger-km, for one passenger at average occupancy. It is well-to-wheel: running the vehicle plus producing its energy or fuel. Building trains, ships and track is not counted.

We use our own factors in every country rather than the figures operators publish, because operators measure different things. Some count building the trains and track, and others leave it out. Some divide a train's emissions by its seats, as if every seat were taken, and others by the passengers actually on board. Side by side, their figures would not compare.

Buses and ferries have one factor each. Trains have a factor per country, and a train that crosses a border is weighted by the distance it runs in each country. The CO2 is the distance × the factor, kept to the whole gram.

Rail, per country ​

A country's rail factor depends on how much CO2 its power stations emit and how much of its intercity traffic still runs on diesel. Electric trains carry the emissions of the power they draw, at the country's own generation mix in 2024. Diesel trains carry a fixed 60 g per passenger-km. The two are weighted by the country's diesel share.

The electricity figures come from Ember, a UK not-for-profit that publishes yearly electricity data for every country.

* No source splits intercity from regional there, so the all-services share is used. It likely overstates intercity trains.

Factors are shown rounded to 0.1 g. The CO2 is computed from the unrounded factor.

When Ember publishes final data for the next year, we update every country's grid intensity and the default. The method stays the same.

Other modes and the default ​

Related Documentation ​

• Key Concepts: Journeys, segments and offers
• Getting Offers: Pricing a journey
• Orders: What an order keeps