Train: REM (Rail Emissions Model)

Calculate train emissions with REM, an operator- and country-aware rail methodology that resolves an emission factor per passenger-kilometre through a tiered resolver and multiplies it by distance and passenger count.

This page is aligned to the REM methodology (integration and Calculation API payloads). Use "methodology": "REM" in all new integrations. If you omit methodology on a train item, the API uses your client's configured train default.

OverviewCopy Anchor Link

REM selects an emission factor (grams CO₂e per passenger-kilometre) with a deterministic tiered resolver, then multiplies it by distance and passenger count.

Send operator_name, ISO country codes, departure_date and energy_scope when you have them: they improve tier matching and make results easier to audit.

Factor resolution (tiers)Copy Anchor Link

REM applies this order:

1. Tier 1, operator-reported: used when operator_name matches operator-specific factors for the requested energy_scope, train_type and, when needed, fuel_type and year.
2. Tier 2, operator-reported mix: used when operator_name matches an operator-specific energy mix for the requested energy_scope, train_type and, when needed, fuel_type and year.
3. Tier 3, country-published: uses country-level methodology data when Tier 1 and Tier 2 don't apply and a country context is available (see Country context).
4. Tier 4, activity-based: uses fuel, traction mix and electricity carbon intensity data for the country or region when Tier 3 doesn't yield a factor.
5. Tier 5, global constant: well-to-wheel global rail averages (IEA-based constants), with a pre/post cut-off driven by departure_date when present.

Country contextCopy Anchor Link

For Tiers 3 and 4, the resolver uses origin_country if set, otherwise destination_country (both optional). Values should be ISO 3166-1 alpha-2 (for example DE, SE). The API accepts other resolvable country inputs and normalises them to alpha-2 where possible (for example UK → GB). If neither country field is available, Tier 1 and Tier 2 may still apply; otherwise resolution falls through toward Tier 5.

Distance handlingCopy Anchor Link

After validation, you must provide one of:

• origin and destination, resolved to a route distance;
• distance_in_km, a positive number;
• route_coords, an array of at least two [longitude, latitude] pairs (WGS84). Longitude must be in [-180, 180], latitude in [-90, 90].

Precedence: if distance_in_km is set together with origin and destination, distance_in_km is used for the calculation distance.

Corrections:

• If you send route_coords, the API computes a border-aware path distance (per-country segments, train-type detour factor from REM data). That total becomes the distance used for emissions; no additional "air distance" correction is applied on top.
• If you send distance_in_km without route_coords, REM uses it exactly as sent and applies no detour factor.
• If you send only origin and destination, REM estimates the rail route distance from the straight-line distance between them and the train-type detour factor from REM data.
• For audit and debugging, expanded item metadata may include a border_distance_breakdown when route_coords were used (sequential segments and totals per ISO alpha-3 country). If some segments can't be attributed to a country, a warning may be present.

Sample requestsCopy Anchor Link

Send a quote before booking, then repeat the call with audit set to true once the booking is final. The body is otherwise identical. The third example uses route_coords instead of origin and destination: when route_coords is valid, origin and destination aren't required for distance validation.

{
  "expand": ["items"],
  "items": [{
    "audit": false,
    "type": "train",
    "external_reference": "test_1",
    "origin": "Stockholm",
    "destination": "Malmo",
    "number_of_travelers": 1,
    "train_type": "high_speed",
    "seat_type": "second_class",
    "fuel_type": "electricity",
    "operator_name": "sj",
    "methodology": "REM",
    "departure_date": "2025-06-15",
    "origin_country": "SE",
    "destination_country": "SE",
    "energy_scope": "wtw"
  }]
}

DefaultsCopy Anchor Link

Request fieldsCopy Anchor Link

Origin and destination formatsCopy Anchor Link

SQUAKE tries to resolve origin and destination whatever their format. Ideally, use:

• Addresses: Post/standard postal format.
• Airports: IATA/ICAO (^[A-Z]{3,4}$, for example MUC).
• Ports and trade locations: UN/LOCODE (^[A-Z]{2}\W?[A-Z2-9]{3}$, for example DEHAM).
• Coordinates: ^[-+]?\d{1,3}\.\d{1,10}\s?,\s?[-+]?\d{1,3}\.\d{1,10}$ (for example "+40.712,-74.006").

UIC and provider codesCopy Anchor Link

Invalid or unsupported codes may trigger a fallback to more generic (non-journey-specific) factors.

Send <provider>:<uic_code>, for example sncf:FRAAA. Possible provider prefixes: uic, uic8_sncf, sncf, sncf_tvs, entur, db, busbud, distribusion, flixbus, cff, leoexpress, obb, trenitalia, trenitalia_rtvt, trenord, ntv_rtiv, ntv, hkx, renfe, atoc, benerail, westbahn.

// Illustrative
{
  "type": "train",
  "methodology": "REM",
  "origin": "entur:7400001",
  "destination": "entur:7400046",
  "operator_name": "sj",
  "number_of_travelers": 1
}

Sample responseCopy Anchor Link

When you expand items, each train item may include algorithm_specifics describing the resolved REM tier and matched metadata (for example tier, energy_scope, gco2e_per_pax_km, year_matched, country_matched, operator_matched, source_links and resolver details). The exact shape follows the live API.

{
  "carbon_quantity": 261,
  "carbon_unit": "gram",
  "items": [{
    "carbon_quantity": 261,
    "carbon_unit": "gram",
    "external_reference": "test_1",
    "type": "train",
    "methodology": "REM",
    "distance": 616.0,
    "distance_unit": "kilometer",
    "algorithm_specifics": {
      "tier": 1,
      "energy_scope": "wtw",
      "gco2e_per_pax_km": "0.42",
      "year_matched": 2024,
      "country_matched": "se",
      "operator_matched": "sj",
      "source_links": [],
      "methodology": "operator_reported"
    }
  }]
}

White paperCopy Anchor Link

• SQUAKE: Rail Emissions Model Whitepaper.
• REM: Rail Emissions Model.