Final answer:
When printed instructions require the train operator to secure the train, it means that the operator should ensure that the train is parked in a safe location.
Step-by-step explanation:
When printed instructions require the train operator to secure the train, it means that the operator should ensure that the train is parked in a safe location. This involves finding a designated parking area or station where the train can be safely kept. The operator needs to ensure that the train is secured and parked properly to prevent any accidents or unauthorized access.