Comment

2 July 2009

Sometimes tunnel vision is effective

Ground penetrating radar may be the new technology that can help detect criminals digging tunnels along the U.S. border.

Of all the tunnels found to date, technology has not played a major factor.

“All of them have been found by accident or human intelligence,” said Ed Turner, a project manager with the U.S. Department of Homeland Security Science and Technology Directorate (S&T).

Agents discovered this tunnel in Nogales, Ariz. The other end was in Mexico. Officials arrested five drug trafficking suspects and destroyed the tunnel.

To find the tunnels, Turner said technology has to come to the forefront. That is why they partnered with Lockheed Martin to pursue a fresh approach that uses ground penetrating radar.

The Tunnel Detection Project is part of the Homeland Security Advanced Research Projects Agency, an office within S&T. If successful, the tunnel detection technology will help agents locate and plug tunnels almost as fast as the criminals can dig them.

While people use most tunnels to move drugs or people, they could also move weapons and explosives. Tunnels are a serious challenge for border patrol agents because they can begin and end almost anywhere and their entrances and exits often go undetected inside old warehouses or under trees. If officials find old ones, new ones quickly replace them. 

The first thought was to use an unmanned aircraft equipped with radar technology that would fly along the border searching for tunnels. While this concept remains a goal, department scientists and agents realize most of the existing tunnels run through large urban centers where they are difficult to spot from satellite imagery. In addition, the airborne radar’s radio frequency signals pose privacy concerns if they cross into someone’s home.

The new design technology has radar antennas in a trailer towed by a Border Patrol truck. The antennas shoot a signal directly into the ground and use it to construct a multi-colored picture of the earth. Tunnels show up as red, yellow, and aquamarine dots against a blue background. Border patrols agents would see these images on a monitor mounted inside their truck.

Ground penetrating radar shows promise because civil engineers already use it to reconstruct underground images. These engineers, however, are usually only interested in detecting cables or pipes that may be a few meters beneath the earth. S&T must find tunnels that often run much deeper. To find these, the radar uses much lower frequencies that penetrate the ground much better, and a sophisticated new imaging technology that can display clear pictures of deep tunnels.

The Lockheed Martin team tested a scale model prototype this spring, mimicking the Southern U.S. border with large box filled with sand and rocks, and using pipes as tunnels.

The next move will be to field test the technology in the Southwest this summer. There it will face real-life scenarios. Separating tunnels from rocks, plants, and other objects along the ground or buried shallowly will be a key test.

“We want to develop something that can be used with high reliability so you’ll find tunnels and not other things in the ground,” Turner said.

For related information, go to www.isa.org/sensors.