Hello rikicecchi,
I think you are looking for the npchlc_traffic and npchlc_traffic_editor resources. They were created by @Reyomin, previously known as CrystalMV, a highly reputable member inside of our MTA community. You can see the node editor in action in this video:
There does not appear to be any documentation on the MTA wiki regarding this resource. You should try following the regular MTA wiki editor plugins documentation for getting the traffic plugin to work. If you are facing any difficulty, feel free to ask!