{HEAD ~ Apparatus} for establishing {TAIL ~ electrical conductivity} between a reference electrode and soil under a pavement layer comprising: 
for establishing
{ HEAD ~ Apparatus } for establishing { TAIL ~ electrical conductivity } between a reference electrode and soil under a pavement layer comprising :
HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH