Guardrails in public places are generally to guard against people falling over, or to protect against unauthorised entry to an area or premises.
In the photos, the area is uneven. There is a step between the two surfaces. Hence, the guardrails are to guard against people walking off the step accidentally. They are also very useful for seniors who have a problem with the slopes.
Their lovely shadows present themselves when I walk past them in the afternoons. On the day when I was not in a hurry, I stopped to take some photos for the Shadow Hunters contest.
“In the dark, where do shadows go?” - Orson Scott Card
The Shadow Hunters Contest/SMASh is run by 
