Train Arrival Webhook - Cedar.AI Documentation

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

{
  "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.

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:

POST /your-webhook-endpoint HTTP/1.1
Content-Type: application/json
X-Webhook-Timestamp: 1709651400
X-Webhook-Signature: <base64-encoded-ed25519-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 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

Configure Workflow

In ARMS, create or edit a workflow rule that triggers on train arrival events.

Add Webhook Effect

Add the Train Arrival Webhook effect to the workflow. Provide your endpoint URL.

Implement Your Endpoint

Build an HTTPS endpoint that receives the POST, verifies the signature, and processes the event.

Test

Trigger a test event and confirm your endpoint receives and verifies the payload correctly.

Webhook Overview

Signing, verification, public key, and shared HTTP headers.

Car Actually Placed

Webhook for individual car placement events.

Train Departure

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 payload.

​Event Overview

​Payload Schema

​Field Reference

​Top-level Fields

​linked_resources.equipment

​linked_resources.event_station

​attributes

​Example HTTP Request

​Differences from Car Actually Placed

​Setting Up This Webhook

​Related

Webhook Overview

Car Actually Placed

Train Departure

Event Overview

Payload Schema

Field Reference

Top-level Fields

linked_resources.equipment

linked_resources.event_station

attributes

Example HTTP Request

Differences from Car Actually Placed

Setting Up This Webhook

Related