Have you noticed those coloured marks that appear occasionally on our footpaths? They obviously indicate the presence of utilities, so I did some googling to find out more. Perhaps, not surprisingly, there’s a lot to know!
There’s a “dial before you dig” service, and detailed procedures to be followed. It seems there are various techniques to identify the location of sub-surface assets, such as radar and electro-magnetic devices, and these are used by “certified locaters” .
There’s an Australian Standard (AS 5488) that recommends the utility code and line colour for each subsurface utility type, which is here. I see that white is for telecommunications, green is for stormwater/raw water (does this include sewerage?), red is for “fire service”, orange is for electricity, yellow is for gas, pink is for “unidentified”, purple is for recycled water and blue is for potable water.
I haven’t looked in detail as to how the identifying equipment works. For example, it would seem to me to be difficult for technology alone to distinguish recycled water from other types of water. And there must be special technology that can detect pipes etc made from plastic, or anything else that does not conduct electricity (and does not have a tracer wire affixed). However, for now, I shall just observe the markings with respect for the technology that enables them to be made.

















