One may think in this modern age that digging a tunnel to escape the authorities just doesn’t happen anymore. But on the US border, it is a common activity for drug-trafficking criminals who try to smuggle their substances across the US border.
“All of them have been found by accident or human intelligence,” said Ed Turner, project manager with the US Department of Homeland Security (DHS) Science and Technology Directorate (S&T).
Over the last three years US border patrol agents have found an alarming increase in the rate criminals have been digging tunnels, with new ones usually found each month. One such tunnel was found ending on the Mexican side of the US–Mexico border in Nogales, Arizona. Later, five drug trafficking suspects were arrested and the tunnel destroyed.
Entitled the “Tunnel Detection Project”, DHS S&T is exploring a new approach using sophisticated ground penetrating radar to detect these secret burrows to help agents locate and destroy tunnels as fast as the criminals can dig them. Tunnels are a serious challenge for border patrol agents because they can start and finish almost anywhere and it’s not only drugs that are smuggled across tunnels, but people, weapons and explosives.
Originally plans were made for unmanned aircraft equipped with radar technology to fly along the border, but most existing tunnels run through large urban centres, making it difficult to detect using satellite technology. In addition, the airborne radar’s radio frequency signals pose privacy concerns if they cross into someone’s home.
Ground penetrating radar is already used by civil engineers to cables and pipes underground, but is being adapted by DHS S&T to detect much deeper. Imaging technology is also being developed that can display clear pictures of deep tunnels from the radar.
Later this summer, these radar antennas will be placed in a trailer that will be towed by a Border patrol truck at the actual border. Separating tunnels from rocks, plants and other objects along the ground or will be a key test.