​Red brushes at airport bus stop

I was waiting for the bus to take me home from the airport (Edinburgh, if that’s relevant) and saw that each bus shelter had 2 or 4 of these bristle-y brush things. they all face toward the road, they’re short enough that they don’t stick out beyond the curb. Seem to be made of a flexible plastic. Cannot for the life of me work out what purpose they serve. They don’t touch the buses that come by, they face away from pedestrians, they’re only about waist-height.