Barriers (in everyday life) 5
The first two barriers here serve more to control pedestrian flow away from or around instead of blocking. The Coal Drops Yard advertising makes the most of the temporary screen which is there to block sight and entry, while the metal window grille and red barrier concern themselves with blocking entry only.
Sunglasses can block harmful rays, but like the blacked-out car windows they also provide a level of privacy.
Meanwhile, builder use their rubbish bags as an instant unofficial barrier to would-be car-parkers, much like passengers and casual diners use their bags on neighbouring seats.