How to make a visually pleasing slope

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[View the Tutorial] 

…exactly the way you want it, without the help of a slope mod.

Yes, it‘s right. We’ll attempting the almost impossible: Creating a slope that looks good, exactly the way we want it, without resorting to a slope mod. The goal of this tutorial shall be: We will be (for demonstrational purposes) making an overpass with the height of 7.5m over a railway line, where the terrain rises exactly by 1.5m per city tile. (This requires making a slope that takes up 5 city tiles.)