Uh-Oh, What's Going On?

Going down the street the other day on my walk I spotted this triangle in the street, over to one side.  I knew immediately what it was.  A surveying team has passed through here and they set up their equipment and to mark where they took their readings, they drive a nail into the street with a bit of orange plastic under the head of the nail, and then they spray an orange triangle around it, so it can be easily found later on.  Now the question is, WHAT are they surveying?  Well, the street, obviously, but for what reason?  Are they going to repave the street, or install a sewer line or do something else?  Stay tuned, and I will report back.