Across tree, without shift
![Image](https://forums.factorio.com/images/ext/c6f554c1a061407671d073b8e1b43c3a.png)
Across tree, with shift
![Image](https://forums.factorio.com/images/ext/4fa2d894eb97ea4e55aeb40aeb7d83d7.png)
Across rock, without shift
![Image](https://forums.factorio.com/images/ext/e262523d4a6bb4c7944d3ca590aed2cf.png)
Across rock, with shift (no change!)
![Image](https://forums.factorio.com/images/ext/e262523d4a6bb4c7944d3ca590aed2cf.png)
This causes all sorts of weird bumps in the track when trying to go longer distance, as it's avoiding all rocks instead of removing them.