Geometry Nodes: Curves support extruded junctions

Using Geometry Nodes curves to build semi-procedural roads or train tracks is great but it quickly falls over when you need to extrude a node and branch off from the main section.

To help us understand a little more, I will borrow the skin modifier for terms.

• The trunk: The first curve on which all other branches form
• The branch: a curve extruded from a node
• The junction node: the node which branches meet

I would like to provide a model or a procedure that can handle the junction site in two ways:

1. Semi-procedural

In this case, when a train track is branching replace with an Object in the scene with rules about accepting multiple branches defined in its own Geometry Node, the effect would be a semi-procedural generated turnout or points based on the angle of the new branch relative to the tangent angle of trunk.

2. Procedural

When a road is branching provide the same but as this model is simpler, just define some rules without using an object in the scene.

The problem:

TIA!