If a council ever said anything about it i would point out every time there is a political campain the streets are full of signs on lamposts for around a month. This would be more dangerous as its ment for drivers to see where as reverse graffiti on the floor so only pedestrians will see it therefore be less of a danger. If they can let 1000s of signs go up around the town for politians why would a few signs on the pathment be any difference
