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Good eye and I like the way you're thinking, but I think it's a survey marker pin with marking around it to draw attention to it.
Also, the triangle's longer legs seem to point to the left and was striped over. Compass direction? Points to underground pipeline?
The road seems not too long ago resurfaced and re-stripped. Pin and markings related to that, lets equipment operators know where it is?
Good job watcher!!
It is a survey control point.
I think it’s some kind of code.