It's an issue with Extra Train Station Tracks itself. I could have sworn this got fixed, but I definitely see it happening with just that mod and none other enabled. Nothing to do than live with it for now until the mod gets an update. Or switch to using regular metro instead.
The best way for us to see what's happening is to have a look at your output log (player.log on Mac and Linux). When it happens, tab out of the game (or shut it down through the task manager) and upload the log, so it's right after it happens. This guide explains where to find it and has some suggestions for where you can upload it to, since we can't attach files here on Steam.
https://steamcommunity.com/sharedfiles/filedetails/?id=463645931&searchtext=log...
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