What happens when a train operator presses the route request button successfully?

When a train operator presses the route request button successfully, a light indicates the request has registered in the tower. This signal is essential for communication between the train and the control tower, confirming that the route change or request has been acknowledged. The light serves not only as an immediate feedback mechanism for the operator but also as a verification for the control tower that they must process the request, ensuring the safety and efficiency of train operations.

The other options do not accurately reflect the process that occurs following a successful route request. For instance, there is usually no automatic slowing down of the train just from pressing the button, as speed adjustments are typically managed through different protocols. Similarly, alarms for alerting passengers or verbal confirmations for the operator are not standard immediate responses associated with this action. The light confirmation is an integral part of the operational protocol that helps maintain a clear and safe communication channel during train operations.