Tweened curve division and cross connection between points

Hey,

I have trouble connecting ''border'' points of divided curves. The final goal is to have two rails that run every other cross section, but that part can be organized with patterns lists and cull options. I would appreciate if someone can help me connect the dots on the other curves for starters.

If you feel like it you can use horizontal intersection planes that cut the contours but I didn't manage to cross-connect those as well.

Thank you in advance