Are these pavement markings anything to do with BT internet/openreach?
Blue marking is normally for water companies
The mark is on top of the service. So either another company is going to excavate in the area and don't want to damage the water pipe or the actual pipe is going to be renewed so its position is marked prior to the dig.
I think on top of the mark they should put some notes (on paper) or another way of information about a mark, it will be useful, because I was confused by the first time too.
Don't know why the utility companies need to explain in a leaflet what they are doing. Those that need to know about do.