A year or so ago, complaints were made to the NW about one home owner placing 11 ropes on the road in front of his residence up 'north'. I went to the Mayor and the Traffic Dept, who told me they did have authority to remove the ropes IF an official letter of complaint was received about them. Verbal complaints were disregarded. No one wanted to be the 'bad guy' and write a letter of complaint against the resident.
I don't know about what's legal or not, I'm just giving my experience of a similar situation.