Is it possible?

Well, maybe not a straight up and down ladder, but maybe something useful like a bridge?

Bridge wouldn't be useful because there were no water masses that necessarily needed to be built across. Also if you're wondering, the reason that making ladders and climbing up vines doesn't work was because there's a ceiling. In the book (I don't remember if it happened in the movie) there's a part where the sun disappears, yet that's because there was no sun to begin with.
TL;DR: They're in a box basically

I didn't mean a bridge to cross water, more like a pathway to build up

Eh, nothing would work. The only exit is through a Transmat hole called the Griever Hole where the Grievers come out of.

Why did I get down voted? I can understand not agreeing with someone's opinion, but down voting a random fact? That's ridiculous.

It's okay doof, just go build a getyourfactsstraightenator.

Way ahead of you. But I think I'll call it a "factenator" for short.

link?

Here it is on YouTube, I've set the start and end times so it will begin and end at this exact segment (down to the tenth of a second)!
http://bit.ly/1AZsxta
You can watch the whole thing by just clicking in the seek bar.
- FunStats

Thanks :D