a first container including a permeable bottom closure and means for supporting {HEAD ~ a first reference electrode} in {TAIL ~ electrically conductive engagement} with said bottom closure, said first container being operable to be supported on the surface of a pavement layer over a predetermined point for establishing electrical conductivity between the soil under said pavement layer and said first reference electrode; and 
a first container including a permeable bottom closure and means for supporting { HEAD ~ a first reference electrode } in { TAIL ~ electrically conductive engagement } with said bottom closure , said first container being operable to be supported on the surface of a pavement layer over a predetermined point for establishing electrical conductivity between the soil under said pavement layer and said first reference electrode ; and
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH