An inspection system to measure the condition of at least a wall of a ground opening, the inspection system having a head unit for lowering into a borehole during a data collection phase wherein at least one set of test data is collected concerning one or more physical characteristics of the borehole during the data collection phase, the head unit having an internal measurement system and a sensor arrangement with a plurality of sensors facing radially outwardly of a head axis that is generally parallel to at least a portion of a borehole axis, the plurality of sensors allowing the head unit to be moved during the data collection phase without rotation about the head axis, the plurality of sensors at least partially producing the at least one set of test data collected during the data collection phase.