The tracks work very similar to roads now, so you just press page down a few times to get them underground.
It could be lack of RAM, it could be a mod issue. If you can post your output log (player.log on Mac and Linux) and the error.log from the crash, then we can take a look. If you get the pop up when it crashes, it mentions a folder where you can find those files. Otherwise this guide explains where to find the logs, and it suggests some places you can upload the log to, since we can't attach files here on Steam.
https://steamcommunity.com/sharedfiles/filedetai...
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