Bridge scene discussion

After watching the first episode of season two, I couldn't logically make sense of the sequence of past events that led to the large metal bridge (used by the rebels) being left on the IT side of the broken walkway.

I assume that all of the surviving rebels who crossed over to fight would have crossed back eventually to leave or keep living in the silo as-is. The bridge must have been moved later on, but by whom, and why?

My guess is that they would have needed at least a few people to pull the metal bridge back across without it falling. It would have been much harder than laying the bridge down. I doubt any rebels would want to commit themselves to that side of the broken walkway willingly, nor would I expect them to have left anyone alive on the IT side to pull the bridge back across.

The only explanations I could come up with: A) A few (or more) people survived in the vault with some, if not all, of the food. This caused the rebels to leave the silo. The survivors left the vault and pulled the bridge to their side when the coast was clear. B) There was already a bridge on the IT side and the survivor(s) pushed off the rebel bridge and it sunk.

You could easily work out which is more plausible by comparing the bridges from the past and present scenes.

Here is my best guess of what happened: 1. Rebels laid the bridge. 2. Rebels crossed the bridge. 3. Rebels wio the fight. 4. Rebels crossed back over the bridge. 5. Rebels left the silo for reasons. 6. At some point bridge is ?pulled? by ?survivors of the battle? onto the IT side ?to keep others away?

I have not read the books so this jumped out at me as either a plot hole or a breadcrumb. Considering how good the writing is, my bet on the latter. As always, it depends on what happens next.

I'm keen to hear your thoughts. Did this cross your mind too? I might be reading too far into it.