In the states, there are companies that specialize in knowing where every fiber is located. You call 411 and for free they come mark it and any other utility as well.
Years back our phones went down. When that happens you drive around till you find the guys that are digging so you can get an idea of how long it will be out.
Found the guy standing next to his rig and asked him what happened. “The flag guy miss flagged it.” he said, “now stay a moment and you will see the magic flags appearing. “
Sure enough, this small truck comes to a screeching stop in front of us. The flagger jumps out and starts stabbing flag in the ground around the hole. Jumps back up in his truck and peels out and disappears.
Next the local administrator for the telco shows up and starts berating the construction guy while pointing at the flags and explaining how much it was going to cost the worker. He then leaves.
I asked him, aren’t you concerned? Smiling he said “Nope, I took pictures before you got here”. Don’t you love those magic flags.