Train: GREEN-TRAVEL-DATA 🇬🇧
Calculate GB National Rail journey emissions with the Rail Delivery Group's Green Travel Data figures, using the release whose timetable covers the departure date.
Use "methodology": "GREEN-TRAVEL-DATA" for the Rail Delivery Group's Green Travel Data (GTD), formerly Green Travel Pledge. The former name GREEN-TRAVEL-PLEDGE is still accepted and calculates the same way.
Overview
Green Travel Data is the GB rail industry's figure for the emissions of a National Rail journey: kilograms of CO₂e per passenger for the whole journey between two stations. It comes for first class, for standard class, and for all passengers together. The Rail Delivery Group (RDG) calculates it from the planned timetable, the traction and length of each train, and forecast passenger numbers. RDG publishes it for each timetable period (a release). From the timetable starting 14 December 2025, a release covers every pair of National Rail stations, whether the journey is direct or has changes. The earlier releases covered direct journeys only.
SQUAKE keeps every release and calculates each journey with the figures of its own timetable.
Sample requests
Send a quote before booking, then repeat the call with audit set to true once the booking is final.
{
"expand": ["items"],
"items": [{
"type": "train",
"methodology": "GREEN-TRAVEL-DATA",
"external_reference": "test_1",
"origin": "KGX",
"destination": "EDB",
"number_of_travelers": 2,
"seat_type": "second_class",
"departure_date": "2026-03-01"
}]
}audit_for is optional
Pass the ID of an auditable entity when you calculate on behalf of that entity. Otherwise, leave it out.
Request fields
typestringrequiredtrain
methodologystringrequiredGREEN-TRAVEL-DATA. GREEN-TRAVEL-PLEDGE is accepted as the former name.
originstringrequiredThe CRS code of a GB National Rail station, for example KGX for London Kings Cross. SQUAKE doesn't resolve station names, UN/LOCODEs, addresses or coordinates for this methodology.
destinationstringrequiredThe CRS code of a GB National Rail station, for example EDB for Edinburgh. Same rules as origin.
seat_typeenumfirst_class, second_class or average. Defaults to first_class. See Seat types.
departure_datestringISO date YYYY-MM-DD. It picks the release whose timetable covers the date. When no release covers it (before the first release, between two releases, or after the latest one), the latest release is used. Defaults to today.
number_of_travelersintegerMinimum 1. Defaults to 1.
distance_in_kmnumberOnly used to calculate when the release has no figure for the station pair, see Calculation. When sent, it's also the distance in the response; without it, the response has no distance.
external_referencestringCorrelates request and response, up to 128 characters.
auditbooleanSet to true to create immutable audit records for finalised calculations. Must be enabled for your account.
POST /v2/calculations in the API referenceSeat types
seat_type | Green Travel Data figure | When the release has no such figure for the pair |
|---|---|---|
first_class | First class | Standard class, then all passengers |
second_class | Standard class | All passengers |
average | All passengers | — |
The releases before 14 December 2025 have no first-class figure on routes without first class.
Calculation
Journey figure
SQUAKE takes the kilograms of CO₂e per passenger for the station pair and seat type, in the release picked by departure_date, and multiplies by number_of_travelers.
kg per passenger × travellers × 1000departure_date.number_of_travelers from the request.When the release has no figure for the pair
This happens for a station the release doesn't list or, in the releases before 14 December 2025, a journey with changes. SQUAKE then uses RDG's GB-wide figure per passenger-kilometre for the seat type, which RDG publishes for journeys that have no station-to-station figure, and multiplies it by distance_in_km.
kg per passenger-km × distance × travellers × 1000distance_in_km from the request.number_of_travelers from the request.distance_in_km is needed for the fallback
Without distance_in_km the calculation fails with green_travel_data_emission_not_found. A calculation made this way carries "figure": "passenger_km" and, in audits, "fallback_data_used": true.
Sample response
{
"carbon_quantity": 27581,
"carbon_unit": "gram",
"items": [{
"carbon_quantity": 27581,
"carbon_unit": "gram",
"external_reference": "test_1",
"type": "train",
"methodology": "GREEN-TRAVEL-DATA",
"methodology_version": "3.1",
"algorithm_specifics": {
"timetable_start": "2025-12-14",
"timetable_end": "2026-05-16",
"timetable_covers_departure_date": true,
"figure": "journey",
"seat_type_used": "second_class"
}
}]
}algorithm_specifics names the release used (timetable_start, timetable_end, and whether its timetable covers the departure date), whether the figure is the journey's or the per-passenger-kilometre one (figure), and the seat type whose figure the calculation uses (seat_type_used).
methodology_version is the Green Travel Data version of that release: 2.0 for timetables before 14 December 2025 and 3.1 from then on. Audits record the same version.
Audit mode
The audit's emission factors record co2_per_passenger_grams (the journey's grams per passenger), fallback_data_used, and, for a per-passenger-kilometre figure, co2_per_km_grams.
Errors
| Code | When |
|---|---|
green_travel_data_emission_not_found | origin or destination isn't a CRS code of a GB National Rail station, or the release has no figure for the pair and no GB-wide figure can stand in (no distance_in_km, or no per-passenger-kilometre figure in the release). |
invalid_date_format | departure_date isn't a YYYY-MM-DD date. |
invalid_params | seat_type isn't one of the three seat types, or distance_in_km isn't a positive number. |
request_failed | Green Travel Data is temporarily unavailable. Retry later. |
Bibliography
Rail Delivery Group: Sustainability and Green Travel Data.