Train: REM methodology v2.7

We’ve updated SQUAKE’s Rail Emission Model (REM) to version 2.7. This release refreshes and expands the verified rail emission factor dataset across all five REM tiers, updates train-type and detour-factor coverage, and improves consistency across REM calculations.

What's New?

Updated Tier 1–5 Emission Factors

REM v2.7 introduces updated and re-validated emission factors across Tier 1 through Tier 5, including refreshed operator-specific, country- and service-specific, and fallback values.

The dataset also expands validated operator and country coverage. As a result, the most specific factor resolved for a rail journey may differ from the previous REM version.

Expanded Train-Type Coverage

REM now supports the expanded set of canonical train types available in the latest dataset, including categories such as commuter and urban_rail where applicable.

This allows REM to use more specific factors when they are available instead of falling back solely because a train type was not previously supported.

Updated Detour Factors

Detour factors used to estimate rail-route distance have been updated and expanded.

These factors are applied only when SQUAKE needs to estimate rail-route distance from straight-line origin/destination distance. They are not applied when an actual rail-route distance or passenger-kilometre value is already available.

Because of this update, calculations where the rail distance needs to be estimated may change compared with earlier REM versions.

Fallback Logic Remains Unchanged

The REM fallback hierarchy remains:

Tier 1 → Tier 2 → Tier 3 → Tier 4 → Tier 5

REM continues to use the most specific verified factor available for the provided journey data. It does not create a synthetic average factor from a specific train or service type when a verified average is unavailable.

Tier 4 remains country-specific, while Tier 5 continues to provide the global fallback.

What This Means for You

No change is required to existing integrations that already use the SQUAKE train methodology.

However, recalculating the same rail journey with REM v2.7 may produce a different result where:

• an emission factor has been updated or corrected;

• new operator or country coverage provides a more specific factor;

• expanded train-type coverage changes factor resolution; or

• an updated detour factor is used to estimate rail-route distance.

For more information about the Rail Emission Model, see the SQUAKE Rail Emission Model whitepaper.