Finding the pattern

If a bollard is a short vertical post then I guess these are bollards. But they don't have anything to do with mooring boats or ships, or directing traffic.

They're a feature near where I work, through a park area where there is a shallow, dry stream creek. These cross from one side of the dry stream bed to the other.

Anyway, they puzzled me with their am-I-or-aren't-I-a-bollard stance, and intrigued me with their pattern.

A bit like work really, spotting the pattern when something isn't quite working and trying something different. I get to do that a bit because I'm new and see things with fresh eyes. 

I think I have some earnest cold bugs knocking on my system. I will slink off to bed early.