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Switchback Automation

A bare layout showing some logic configurations for automating switchbacks. Click the Start lever to see operation.

For a self-contained switchback automation circuit module with more advanced features see Switchback Automation Module.

Description

At right is the simplest configuration that I have been able to make.

At upper left is the same method, implemented with the Turnout & Signal Controller module.

At lower left is a more sophisticated version that sets the turnout correctly for an approaching train and uses a delay to perform the switching while the train is changing direction. This method could also be implemented using the TSC 1 module.

All methods can process any sequence of arrivals from either direction.

I do not require attribution if you incorporate this logic into a published layout, but if you do so please post a link in the comments so I can see it in action.

Technical notes:
- The train detection switches closest to the turnout are set to End only. These set the turnout for departure from the switchback.
- The train detection switches farther from the turnout (lower left configuration only) are set to Start only. These set the turnout for arrival at the switchback.
- Wireless (password) communication can be used from the train detection switches to the logic gates.
- This configuration can also be used to set a turnout to a guaranteed position regardless of its current state. Anything that sends a pulse to the OR gate terminal used by the train detection switch will guarantee that the turnout is set straight, and anything that sends a pulse to the AND gate terminal used by the train detection switch will guarantee that the turnout is set to turn.