> For the complete documentation index, see [llms.txt](https://docs-integration.squake.earth/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs-integration.squake.earth/notable-changes/calculation-changes/train-epa-live.md).

# EPA Train Methodology — Now Live

**What:** Train emissions via the US EPA *GHG Emission Factors Hub*. Factors in **gCO₂e/pax‑km** (CO₂, CH₄, N₂O). If `methodology_version` is omitted, **latest supported year** is used.

**Supported `train_type`:** `intercity_northeast_corridor`, `intercity_other_routes`, `intercity_national_average` *(default)*, `commuter_rail`, `transit_rail`.

**Do now:** Use **US‑EPA** for U.S. rail; add `"methodology_version"` if you need fixed‑year reproducibility.

**Source:** US EPA — GHG Emission Factors Hub.