> ## Documentation Index
> Fetch the complete documentation index at: https://docs.cedarai.com/llms.txt
> Use this file to discover all available pages before exploring further.
# Train Arrival Webhook
> Event payload sent when a train arrives at a station
## Event Overview
The **Train Arrival** webhook fires when a train arrives at a station in your network. It delivers equipment details, the arrival station, loaded/empty status, the train number, and the associated work order (if any).
This webhook is triggered through ARMS workflow automation. Configure it in your workflow rules to notify external
systems when trains arrive at specific locations.
***
## Payload Schema
```json theme={null}
{
"event_type": "TrainArrival",
"event_timestamp": "2026-03-10T08:15:00+00:00",
"work_order_id": "a1b2c3d4-e5f6-7890-abcd-ef1234567890",
"linked_resources": {
"equipment": [
{
"resource_id": 100001,
"car_number": "TTGX 995823"
},
{
"resource_id": 100002,
"car_number": "BNSF 726451"
}
],
"event_station": {
"resource_id": 500,
"grouping_type": "station"
}
},
"attributes": {
"is_loaded": true,
"train_number": "T-4521"
},
"actor": {
"resource_type": "User",
"resource_id": 12345,
"display_name": "ops@customer.com"
}
}
```
***
## Field Reference
### Top-level Fields
| Field | Type | Required | Description |
| ------------------ | ----------------- | -------- | --------------------------------------------------------------------------------------------------------------------------------------------------- |
| `event_type` | string | Yes | Always `"TrainArrival"` for this event. |
| `event_timestamp` | string (ISO 8601) | No | When the train arrived. `null` if unavailable. |
| `work_order_id` | string | No | ID of the associated work order. `null` if the event has no work order. |
| `linked_resources` | object | Yes | Equipment and station involved in the event. |
| `attributes` | object | Yes | Event-specific attributes. |
| `actor` | object or null | Yes | Who caused the triggering event. `null` for system-initiated events. See [Shared Payload Fields -> actor](/user-docs/arms/webhooks/overview#actor). |
### linked\_resources.equipment
An array of equipment items on the arriving train. Always an array, even for a single car.
| Field | Type | Description |
| ------------- | -------------- | ------------------------------------------- |
| `resource_id` | integer | Internal equipment identifier. |
| `car_number` | string or null | Railroad car number (e.g. `"TTGX 995823"`). |
### linked\_resources.event\_station
The station where the train arrived. `null` if no station is associated.
| Field | Type | Description |
| --------------- | ------- | ----------------------------------------------- |
| `resource_id` | integer | Internal station identifier. |
| `grouping_type` | string | Type of location (e.g. `"station"`, `"track"`). |
### attributes
| Field | Type | Description |
| -------------- | -------------- | ----------------------------------------------------------------- |
| `is_loaded` | boolean | `true` if the cars are loaded, `false` if empty. |
| `train_number` | string or null | Train identifier (e.g. `"T-4521"`). `null` if no train ID is set. |
***
## Example HTTP Request
This is the full HTTP request your endpoint receives:
```http theme={null}
POST /your-webhook-endpoint HTTP/1.1
Content-Type: application/json
X-Webhook-Timestamp: 1709651400
X-Webhook-Signature:
X-Webhook-KeyId: cedar-webhooks-2026
X-Webhook-Id: 550e8400-e29b-41d4-a716-446655440000
{"actor":{"display_name":"ops@customer.com","resource_id":12345,"resource_type":"User"},"attributes":{"is_loaded":true,"train_number":"T-4521"},"event_timestamp":"2026-03-10T08:15:00+00:00","event_type":"TrainArrival","linked_resources":{"equipment":[{"car_number":"TTGX 995823","resource_id":100001},{"car_number":"BNSF 726451","resource_id":100002}],"event_station":{"grouping_type":"station","resource_id":500}},"work_order_id":"a1b2c3d4-e5f6-7890-abcd-ef1234567890"}
```
The JSON body is **canonically serialized** (sorted keys, no extra whitespace) so the signature can be verified
deterministically. See the [Webhook Overview](/user-docs/arms/webhooks/overview#signature-verification) for verification
instructions.
***
## Differences from Car Actually Placed
| Aspect | Car Actually Placed | Train Arrival |
| --------------- | -------------------------------- | -------------------------- |
| `event_type` | `"car_actually_placed"` | `"TrainArrival"` |
| `train_number` | Not included | Included in `attributes` |
| Equipment scope | Single car typically | Multiple cars on the train |
| Trigger | Car physically placed at a track | Train arrives at a station |
***
## Setting Up This Webhook
In ARMS, create or edit a workflow rule that triggers on train arrival events.
Add the **Train Arrival Webhook** effect to the workflow. Provide your endpoint URL.
Build an HTTPS endpoint that receives the POST, verifies the signature, and processes the event.
Trigger a test event and confirm your endpoint receives and verifies the payload correctly.
***
## Related
Signing, verification, public key, and shared HTTP headers.
Webhook for individual car placement events.
Webhook for train departure events, including customer/serving location.
The `linked_resources.customer_location` and `linked_resources.serving_location` fields are not currently included in the Train Arrival payload, even though the underlying event carries them. They are included in the [Train Departure](/user-docs/arms/webhooks/train-departure) payload.