I'm a little confused by the wording of the section. I quoted the rules section below:
3. 3. Boss & Infected Movement
Each Boss moves towards the Refuge space of his Ditch a number of spaces equal to his Movement value.
Once all the Bosses have moved, each Infected moves towards the Refuge space of its Ditch a number of spaces equal
to its Movement value.
If a Boss or an Infected moves to the Ring I and has any Movement points left, it must be placed in a vacant Barricade
box, but only if there are no Barricade in any of the 3 boxes of the Cave: if any one box is occupied by a Barricade, it
cannot enter the box. Each box can only be occupied by one Barricade, Boss or Infected.
I guess what I'm wondering is why are we moving enemies based on the area of a Ditch (which is two caves), but tackling the impact with the Refuge at the cave level? Is there any lateral movement that could cause a boss or infected to change caves while moving? If not, I'm not sure why the Ditch is being mentioned at in this section and and not a Cave. Am I missing something here?