The first thing I’d try (because it requires the simplest of setups) is a physical material (on ALL train meshes):
Do tell if that’s enough.
In addition, you could also opt to incorporate constrains:
But that might not be applicable in all circumstances - depends on what kind of movement we’re dealing with. And yet another way of dealing with this, or augmenting it, is to place a collider that actively repels physical objects but yet again, it may not be applicable.