How to place guardrails?

Hi guys, I'm building a map and wanted to know how I can use the Forest tool to place the guardrails cleanly next to the roads? This method I have discovered on ECA. Or are there better or other methods to place them?

 

Blender is probably the best/easiest method

(go to 35:18 if it doesn't redirect you there)

 

Hey, thanks! I will even watch the whole video. Looks very interesting