# Train: Green Travel Pledge 💡 **High‑Level Description** **Green Travel Pledge (GTP)** is an industry initiative led by the UK **Rail Delivery Group (RDG)** providing recognised, route‑level carbon data for rail journeys in Great Britain. Under the umbrella **Green Travel Data (GTD)** programme, RDG publishes per‑journey and per‑passenger emissions so businesses can compare rail with car and air and drive modal shift. GTP focuses on **per‑passenger CO₂e** for specific **origin–destination** pairs and, where available, **seat class**. When a journey‑specific figure is not provided, the dataset offers fallback factors per passenger‑kilometre. SQUAKE implements both layers with deterministic fallbacks and preserves comparison values for **diesel car, plug‑in hybrid, battery electric car, and air** for auditability. *** ### **Sample API Requests** #### A. Without audit mode (for pre-booking/quotes) ```json { "expand": ["items"], "items": [ { "audit": false, "type": "train", "external_reference": "test_1", "origin": "GRF", "destination": "MBR", "number_of_travelers": 1, "seat_type": "second_class", "methodology": "GREEN-TRAVEL-PLEDGE", "departure_date": "2025-05-03" } ] } ``` #### B. With audit mode (for finalized/post-booking calculations) ```json { "expand": ["items"], "audit_for": "", "items": [ { "audit": true, "type": "train", "external_reference": "test_1", "origin": "GRF", "destination": "MBR", "number_of_travelers": 1, "seat_type": "second_class", "methodology": "GREEN-TRAVEL-PLEDGE", "departure_date": "2025-05-03" } ] } ``` > **Note:** `audit_for` is optional. Provide when calculating on behalf of a specific Auditable entity; otherwise omit. *** ### **API Request Items** * `"type"`: `"train"` **(required)** * `"methodology"`: `"GREEN-TRAVEL-PLEDGE"` **(required)** * `"external_reference"`: Correlates request/response (max 128 chars). * `"number_of_travelers"`: Minimum `1`. **Default:** `1`. * `"origin"` / `"destination"`: Stations per GTD (GB rail). Standard resolvers (CRS/3‑letter, TIPLOC, name) supported. * `"departure_date"`: ISO date `YYYY-MM-DD`. Used to select the **latest dataset published on or before** this date. If omitted, SQUAKE uses the **latest available dataset** at calculation time (captured in metadata as `dataset_date`). * `"distance_in_km"` (optional): If provided, used **only for fallback** when per‑journey emissions are not available and per‑pax‑km factors must be applied. * `"seat_type"` (optional): One of `"first_class"`, `"second_class"`, `"average"` (**default:** `"average"`). See mapping below. * `"audit"`: boolean (optional). Set to `true` to create immutable audit records for finalized calculations. Must be enabled for your account. *** ### **Seat Type Mapping** * Client → GTP: * `"second_class"` → `"standard"` * `"first_class"` → `"first"` * `"average"` → use dataset `"average"` (where available) or computed average if class values are missing. **Zero‑value guardrails** * If the class value (**standard/first**) is present but equals `0`, SQUAKE uses the **`average`** value for that journey. * If class **and** average are missing or zero, SQUAKE enters **fallback mode** (see below). *** ### **Calculation & Fallbacks** 1. **Primary (per‑journey CSV)** – `gtd-emissions-output-by-journey.csv` * Use the **exact O–D** row for the specified `departure_date` dataset. * Choose class‑specific value (`first` or `standard`) or `average` per the mapping/guards above. * Multiply by `number_of_travelers`. Result is **grams CO₂e** if dataset is already per journey; otherwise convert as per dataset units. 2. **Fallback (per‑passenger‑km CSV)** – `gtd-emissions-output-by-passenger.csv` * Take factor **kgCO₂e/pax/km**; compute: ``` grams = factor_kg_per_pax_km × distance_in_km × number_of_travelers × 1000 ``` * `distance_in_km` is required for fallback. If not provided, SQUAKE attempts to resolve rail distance; on failure, returns `distance_required` error. **Comparison Modes (saved for audit)** * Alongside train emissions, SQUAKE stores comparison values (if provided by GTP dataset) for: * **Diesel Car**, **Plug‑in Hybrid Electric Car**, **Battery Electric Car**, **Air**. * If a comparison value equals `0`, SQUAKE records `"N/A"` meaning **Not Comparable**. *** ### **Default Values** * `"seat_type": "average"` * Dataset selection: **latest published on/ before `departure_date`**; otherwise **latest available** (metadata includes `dataset_date`). *** ### **Sample API Response** ```json { "carbon_quantity": 1580, "carbon_unit": "gram", "items": [ { "carbon_quantity": 1580, "carbon_unit": "gram", "external_reference": "test_1", "type": "train", "methodology": "GREEN-TRAVEL-PLEDGE", "origin": "GRF", "destination": "MBR", "seat_type": "second_class", "dataset_date": "2025-05-01", "data_source": "journey", "distance": 0.0, "distance_unit": "kilometer", "metadata": { "comparison": { "diesel_car_g": 4860, "phev_car_g": 3140, "bev_car_g": 1430, "air_g": "N/A" } } } ] } ``` *** ### **Versions / Dataset Updates** * GTP datasets are periodically refreshed. SQUAKE selects the **latest dataset at or before `departure_date`** (or latest available if `departure_date` is omitted) and returns `dataset_date` for traceability. *** ### **Bibliography** * Rail Delivery Group — **Green Travel Data / Green Travel Pledge** (programme overview & calculator).\ --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs-integration.squake.earth/api-calculations-request-response/travel/train/train-green-travel-pledge.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. 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