This is a tool made in Houdini, you can easily make fences with a simple curve, in Unity or Unreal.
Made in Houdini in 1 Week
Final Result 1.
Final Result 2.
Parameters.
Reference.
You can change the height of the planks.
You can change the curve distance.
Change the number of points on top to have a smoother curve.
Changing the Distance between the horizontal planks.
And finally change the height of the pillars.