Sudden Crashes (Not a noob question)

I've been a route builder for a few years now, so I know all of the typical crashes. Sometimes, you get a bad piece track or wall or whatever it is you are using, and every time you go to add onto it the game will crash. The solution to this is to cut away part of the end and delete it.
My problem is similar to this, but not quite it exactly. I am working on a track that climbs a mountain and runs alongside a river. To make this video, I essentially just started placing track in random places to record the next crash. To my surprise it didn't happen until about five new sections, compared to what it usually is.
Everything was going fine in the beginning of this line, but then this started to happen. When I place some track, with grade set to 1.25%, it occasionally crashes. Sometimes after it crashes, I can still add onto the most recent segment and it will not crash the game, unlike the typical crash as stated above. I have also tried to delete a segment of the most resent section and try again and it worked SOMETIMES, but not always. If it did happen to work, a few sections of track later it'll happen again. This gets real old real fast, and I have to save after every section of new track. It is the same track I've been using before (track from the Virtual New Haven route), and nothing else has changed from when the crashes started from up to the point when I made the switch track to go onto this line (which is also a pretty long distance).
Does anybody know what may be causing this?