By 2014 most of the border will be home to sensor-equipped towers that are linked to a central communications network. But while proponents argue that the system will help stem the flow of illegal immigrants, drugs and arms coming over the border, most experts admit it will do little to guard against people making their way under it.
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Since 2001, more than 100 tunnels have been discovered by U.S. law enforcement, compared with just 15 in the 1990s, and the pace is accelerating. Most of those have been uncovered through human intelligence, since there are no currently available technical means to reliably detect tunnels.
Why don’t we just get Ground Penetrating Radar and Seismic Sensors and place them along the fence as well. The GPR can detect the tunnels and the seismic sensors will detect movement/tunneling efforts.