On the top of the traffic posts is a hole where you put your fingers when you move them. Moreover, that is where chains can be placed so that the posts can work as a whole. Traffic Control Bollards Plastic / Road Parking Barrier Post The traffic control bollards are designed to identify hazards or indicate off-limit areas on the road and will effectively reduce traffic jams. The bollard posts are made of plastic, which makes them lightweight and easy to move around. They will form a highly visible barrier to guide or restrict access. They have reflective silver stripes to make drivers more aware of them, even in the dark.