So, you need to expand, and you have a nice little area where you could place a few structures... If only there wasn't a pesky mountain in the way.

Well, you've come to the right post!

Here's an example of my own:

http://gtm.steamproxy.vip/sharedfiles/filedetails/?id=1120199393

Such a lovely little valley, perfect for expanding my utilites area. But see that little ridge there? It's juuuuust wide enough that buildings won't connect. But! There's a workaround.

First, we take a mine, like so:

http://gtm.steamproxy.vip/sharedfiles/filedetails/?id=1120201237

The mine is the only structure that somewhat ignores mountains -- in fact, it needs them, right? Right! Now, place down the mine blueprint, and connect it to the closest structure.

http://gtm.steamproxy.vip/sharedfiles/filedetails/?id=1120201946

This will flatten that bit of hill between them, giving us a bit of a starter for expanding. Hooray! Quickly cancel the mine blueprint to keep your workers from dragging over resources, and then open up another outdoor structure. I tend to use the base pad normally, since it fits into all the nooks and crannies.

http://gtm.steamproxy.vip/sharedfiles/filedetails/?id=1120203208

See how the hill somewhat overlays the pad's blueprint? Weeeeell...

http://gtm.steamproxy.vip/sharedfiles/filedetails/?id=1120204765

Tadah! That smushes the landscape enough to place the blueprint. Now, we could say good enough, and just use that as a pathway. However, if you take some time to repeat that same process (place a mine or a pad, link them up, delete, move the placement and lay them down again, and so on), you can open up quite a bit of new land:

http://gtm.steamproxy.vip/sharedfiles/filedetails/?id=1120211385

That was done entirely with mines, base pads, and connections, and about an in-game day and a half of work. Sure, it can be a bit tedious, but on the other hand--

http://i.imgur.com/X70PN1o.jpg

(I doubt I'm the first one to do this, but hey, there are probably folks out there who don't know this nifty little trick.)

*Disclaimer: One downside to this is if you save and reload without placing structures in that flattened area, it will all revert to its natural contours, and all your hard work will be lost. Basically, use it or lose it. If you don't build on it right away, place down a bunch of base pads to preserve the flatness before exiting the game, then cancel them immediately after loading it up next time.