i found out what the pipes are for:

they are hot water pipes used for heating people's houses. they go all over Berlin, mostly underground.

however, when they are building roads etc they put them over ground just 'temporarily'. i suspect most have been there a long time though,

or another explanation is that it takes ground water away (because of Berlin's high water table).

there were pink pipes and blue pipes so maybe both are correct.

I understand that the double loop loopiness is to prevent difficulties caused by differential expansion of pipes that would exist if the two pipes butted in locically...
According to the office oracle...