I would have thought the 12 K.V cables are feed cables for the nominally 11 K.V cat cable. The track is your Neutral return path , which would be tied to Earth. As would anything else metallic or capable of conducting electricity to eliminate induced voltages. There may be "neutral" cables , simply to reduce currents flowing through any earth cables and the earth itself. In some very simple systems, the neutral return is through the earth , but i doubt that would be the case with the amperage's involved here. (Kens example is a 3 phase system , where the loads are balanced between the 3 phases, where the return is balanced through the other phases -120 degrees of a rotating generator).
As someone said , it is an age old system that relies on everything having a good earth, so any leakage is high amperage, tripping the supply circuit breakers quickly. It predates double insulated tools etc, and earth leakage detectors, and is still the basis of most electricity supply systems. Nothing wrong with it , but the cables would have a metal sheathing or pipe , that would be tied (bonded)to earth. Hence my question, of why the concrete , which has been answered, thanks
Note: With a reread , I see Ken Mentions he is talking about a 3 phase system , seems i mixed a couple of post together.
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