When cancelling a route on a push button machine, which button should the Tower Operator pull?

When cancelling a route on a push button machine, the correct action is to pull the entrance button associated with the route. This is essential because the entrance button is connected to the initial point of the route, allowing the system to appropriately deactivate all aspects related to that specific route. By cancelling from the entrance, the Tower Operator ensures that all participants in the route receive clear communication that the route is no longer in effect, preventing potential confusion or operational overlap.

In signaling systems, the last button pressed typically pertains to actions intended to activate a particular route rather than cancel it. Signal buttons are designed primarily for initiating routes or commands, while the exit button would correspond to the conclusion of a route, which does not directly facilitate the cancellation process. Therefore, the appropriate action involves focusing on the entrance button that corresponds to the desired route that needs cancellation. This maintains the functional integrity of the signaling system and ensures proper communication across the network.