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Transport Type Inference

When a transport section is created with transport_type: "do_not_know", Dcycle automatically infers the most appropriate transport mode and calculates the distance. This page explains the exact decision logic.

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Why use do_not_know?

Use do_not_know when you know the origin and destination of a shipment but not the transport mode — for example, when processing supplier invoices that don’t specify how goods were shipped. Dcycle applies a standardized inference algorithm to ensure the most realistic emission factor is used.
kms_manual is not allowed for do_not_know sections. Because the emission factor depends on the inferred transport mode (which itself depends on geography), manual distances cannot be meaningfully combined with automatic mode selection.

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Inference Algorithm

The inference runs at section creation time and follows this decision tree: 
Given: origin address, destination address
         │
         ▼
1. Geocode both addresses → get coordinates + country codes
         │
         ▼
2. Check for sea crossing
   Same country AND different landmass?
   (e.g. mainland Spain → Canary Islands, mainland Italy → Sicily)
         │
   ┌─────┴──────┐
   YES          NO
   │             │
   ▼             ▼
Use maritime   Same country AND road-reachable via Google Maps?
distance       (status=OK, distance > 0 km, not a default fallback)
(haversine         │
 or searoute)  ┌───┴───┐
               YES     NO
               │        │
               ▼        ▼
           Use road  Use air distance
           distance  (haversine great-circle)
           (Google   Emission factor:
           Maps)     "aircraft, unspecified"
           travel_method → truck

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Decision Rules

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Rule 1 — Sea crossing (same country, different landmass)

Condition: Origin and destination share the same country code, but their coordinates resolve to different landmasses (e.g. a continental mainland vs. an island). Outcome:
  • Distance: maritime (navigable-water via searoute, or haversine fallback)
  • Emission factor: air — specifically the “aircraft, unspecified” concept
This special case exists because island-to-mainland routes involve a sea crossing where ferry emission factors are unavailable in ecoinvent. Air unspecified provides the most conservative and available estimate. Examples:
  • Madrid, Spain → Las Palmas, Gran Canaria (Spain) → maritime kms, air EF
  • Rome, Italy → Palermo, Sicily (Italy) → maritime kms, air EF
  • Lisbon, Portugal → Funchal, Madeira (Portugal) → maritime kms, air EF

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Rule 2 — Same country, road-reachable

Condition: Origin and destination are in the same country, no sea crossing detected, and Google Maps returns a valid driving distance (status OK, distance > 0, not a hardcoded default). Outcome:
  • Distance: road (Google Maps Distance Matrix)
  • Emission factor: road freight
  • travel_method is automatically set to truck
Examples:
  • Madrid, Spain → Barcelona, Spain → road, truck
  • Paris, France → Lyon, France → road, truck
  • Berlin, Germany → Munich, Germany → road, truck

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Rule 3 — Different countries (or road unreachable)

Condition: Everything else — different countries, or same country where Google Maps cannot return a driving route. Outcome:
  • Distance: air (haversine great-circle between geocoded coordinates)
  • Emission factor: air — “aircraft, unspecified”
  • travel_method stays null
Examples:
  • Madrid, Spain → Paris, France → air (different countries)
  • Madrid, Spain → Damascus, Syria → air (different countries)
  • Copenhagen, Denmark → Reykjavik, Iceland → air (no road route available)

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What stays as do_not_know in the database

The transport_type field on the section always remains do_not_know in the database, regardless of which mode was inferred. The inferred mode only determines:
  1. Which geographic distance record is used for kms
  2. Which emission factor concept is matched during calculation
This means the kms_source field will be null for do_not_know sections in the current API response, since the distance was stored under the inferred transport type’s geographic distance record, not under do_not_know.

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Emission factors used

Inferred scenarioEmission factor concept
Same-country sea crossingaircraft, unspecified (air)
Same-country, road-reachableroad freight, lorry, unspecified
Cross-country / road unreachableaircraft, unspecified (air)
The “aircraft, unspecified” factor covers all haul distances without requiring a distance band, making it the natural choice when the exact route characteristics are unknown.

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Comparison with explicit transport types

do_not_knowExplicit type (e.g. maritime)
Distance calculationAutomatic per inference rulesBased on declared type
kms_manual allowedNoYes
transport_type in DBAlways do_not_knowThe declared type
travel_methodSet automatically (truck if road) or nullProvided by user
Emission factorInferred from geographyMatched from declared type + travel_method + detail

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Frequently asked questions

The inference algorithm prioritises the lowest-complexity mode that can be unambiguously determined from geography alone. For cross-country routes, air is the safest default because:
  • Maritime requires knowing the actual port-to-port routing, which is not available for all country pairs.
  • Rail is not universally available and depends on railway network connectivity.
  • Air operates between any two points on the globe.
If you know the actual transport mode, you should always declare it explicitly rather than using do_not_know.
Dcycle uses a landmass detection algorithm based on coordinates. A sea crossing is detected when origin and destination coordinates fall on different landmasses, even if they share the same ISO country code. This correctly identifies:
  • Mainland Spain → Canary Islands
  • Mainland Italy → Sicily or Sardinia
  • Mainland Portugal → Azores or Madeira
  • Mainland Denmark → Bornholm island
It does not trigger for tunnels or bridges (e.g. Copenhagen ↔ Malmö via Øresund Bridge), because the road routing check passes first.
Yes — use an explicit transport_type instead of do_not_know. If you know the shipment was maritime, set transport_type: "maritime". If it was road, set transport_type: "road" and optionally travel_method: "truck". You can also set kms_manual to override the calculated distance for any explicit type.
The kms value for a do_not_know section is taken from a geographic distance record stored under the inferred type (road, air, or maritime). Because the join that populates kms_source matches on transport_type, it doesn’t find the record stored under the inferred type. This is a known limitation — the distance was correctly calculated; only the source label is unavailable in the API response.

Transport Overview

Full data model, transport types, and distance calculation methods

Create Transport Route

How to create a route with do_not_know sections

Transport Combinations

All valid transport type + method + detail combinations

Get Transport Route

Reading kms, kms_source, and inferred transport fields from a route