Groundradar was tasked with conducting a tunnel lining investigation in the mountains of Lesotho.  A custom radar system was used with air-launched antennas at multiple radials around the tunnel, all mounted to a vehicle.  The data were collected in five runs along the 32 km length of the tunnel and subsequently processed to reveal variations in the tunnel lining thickness, possible void locations and the presence and location of rebar within the

1 GHz air-launched GPR antenna used for tunnel lining survey

lining.