Then they'll keep going. There isn't a cave-in in this tunnel -- there isn't one for a while. 

The morning of their eighth day of travel, Occlus gets a premonition. 

"I have a bad feeling about this one. It may be worth your time to do a chi-based analysis."

Hohenheim stops and closes his eyes in concentration.

"In a mile and a half there's a long stretch of tunnel that is dangerously unstable. I'm going to have to prepare an array." He pulls out a sheet of paper from their notes and starts drafting.

The wagons keep moving.

Occlus keeps alert for any signs of danger before they get to that point.

There aren't any. Yet. No one else knows that there's a potential cave-in, though.

Is Hohenheim going to finish his work before they get to that point?

He looks pretty occupied. Maybe.

If he doesn't have anything by the time the lead wagon is a quarter mile out, she'll go stop it.

His bottleneck seems to be forming the array so that it covers a large enough space. He could make a larger array more trivially, but that would involve trekking outside over the mountains and placing it at key points around the whole potential cave-in area. 

So he does need more time.

She goes up to tell the wagons to stop. Easier to do that than dig them out of a collapsed tunnel.

The wagon-leader is confused about what the problem is, they've traveled this road dozens of times. 

"My companion and I are alchemical engineers. We have been analyzing the tunnels as we cross them, and found structural weaknesses in the path ahead. He is currently working on a design to to stabilize it, but needs more time to complete it."

He audibly gasps in surprise. "Why didn't you say so! You both should be moved to the front -- I'll let Jun know and he can tell us how long we can wait before we have to resupply --" He jumps off and turns around briefly to profusely thank her before continuing on his errand. 

A reasonable person, excellent. She returns to Hohenheim to see if he needs her assistance.

"It'll take me a day or two to come up with something small enough. I already have a larger design -- if someone places these sixty pieces of paper at different parts of the mountain at the same elevation, arranged roughly in a circle, the whole area will be fixed. But I don't know if you would be able to place them quickly enough to ask you to venture outside."

"Unless the caravan does not have a day or two of leeway in their supplies, I do not think it would be worth the effort."

"I should get working as soon as possible, then."

"I will inquire as to the supplies."

She returns to the leader to do so.

They technically have enough supplies, but using them means that they won't have any leeway if anything else goes wrong during the trip.

And how would he rate the chances of something else going wrong?

High. Very high. So, so high. Especially considering how much money is invested in this venture. If she understands.

Of course. Hopefully this will not delay the caravan long. She'll leave him to his business,

It's not that going mountain climbing would be difficult, but it would be inconvenient and she would prefer not to. There's a good chance the wagonmaster is lying in order to secure their best efforts, if he has most of his personal wealth tied up in the success of this venture. But on the other hand, if he is not, Hohenheim would likely be distressed by the failure and distracted from his work. The question is, therefore, is the chance of his distress and the accompanying scholastic disruption worth more than the mountain's privations? The answer, she feels, is yes. She returns to Hohenheim.

"Give me the larger array."

It takes him a second to blink away concentration; he stares at her as though concussed. Then: "Ah, right. I put it away, let me fish it out." 

That happens. Occlus is now the proud temporary owner of sixty-one pieces of paper. "That last one is a rough diagram of where they should go and the orientation of the designs on the paper relative to the other pieces."

"I will return when I have finished." She tucks the paper into an inside pocket, taking a moment to memorize the diagram. Adopting a meditative posture, she breathes slowly in and out, concentrating on wrapping herself in the Force as protection from wind and cold. Eyes glowing a faint purple, she sets off for the entrance at a brisk pace, which almost anyone else would term a dead sprint.