Hi,
Thanks for the question. If you have RailClone 7, you might be better using the new Spline nodes to create this. You can use the divide evenly spline node to add multiple layers of evenly distributed elements. The easiest way to explain is to share a sample scene.
It should be pretty explanatary, but one thing to note is that the Divide Evenly nodes are each assigned a different Material ID. This is then targeted using the Selector node.
If you have any questions about this setup, please let me know.
All the best,
Paul