When I was working on a grid aligned rail system I came up with the following design for a T intersection that both seems more compact than anything (other than the bottle) posted so far and seems to be a unique design as far as I can tell (you can trim it down a bit if you didn't want to fit it to ...

While exploring a new map I walked between a cliff and the shore and was then unable to walk out again.
https://imgur.com/a/DhN6V