# 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.