Most of the fences straddling portions of the 2,000-mile border between the United States and Mexico are made of concrete, steel, wire mesh, and sometimes chain link. Another fence is invisible: It consists of a network of “unattended ground sensors”—motion, sound, metal, and even seismic detectors, often buried in the ground and designed to alert border patrol agents wirelessly to the presence of humans or vehicles.
A virtual fence sounds like a smart solution to border security at a time when illegal immigrants and drug smugglers routinely go around or dig tunnels beneath the physical fences. In reality, the border sensor strategy has been dogged by problems for years. Some of the approximately 13,000 sensors now dotting the border are outdated and deteriorating, and send out more false alarms than real ones.
A $1 billion initiative to bulk up the virtual fence blossomed under President George W. Bush, but it failed to meet its goals and got the ax in 2011, after only 72 miles of the Southwestern border were planted with sensors. A $1.5 billion follow-up initiative called the Arizona Border Surveillance Technology Plan aims to upgrade border radio tower, camera, and sensor equipment. But that project has bumped against delays of its own, most recently in February, when a U.S. Customs and Border Protection spokeswoman said the agency was having trouble adding new wireless equipment to its old surveillance infrastructure due to radio bandwidth problems.
Many existing sensors have been ravaged by nature, the Los Angeles Times reported last fall. Ants have eaten wires and rain has corroded battery terminals.
In 2005 government officials said weather, animals, trains, and other false alarm sources were triggering one-third or more of all sensor alerts. Along the Southwestern border, a sensor was triggered about every 44 seconds, and most of the time Border Patrol agents never determined the cause, due to a lack of manpower needed to check each alarm. When the sensors detected actual illegal aliens, they got away two times out of three. Last October a false alarm turned deadly when Border Patrol agents investigating a sensor accidentally fired on one another in the dark, killing one agent and wounding another.
A string of problems doesn’t always mean we should abandon a goal, but it highlights the persistent challenge of stopping illegal crossings. Another border security technology, flying drones, may help close gaps the sensors haven’t. The Border Patrol’s 10 Predator and Guardian drones helped authorities make 143 arrests and seize 66,000 pounds of narcotics last year.
Fingerprint scanning would seem to be a foolproof identification method, but doctors at an emergency clinic near São Paulo, Brazil, have proved it isn’t. Police arrested 29-year-old Thaune Nunes Ferreira in March after learning she was using silicone thumbs—complete with embedded fingerprints—to fool the clinic’s employee identification system and falsely clock in for her colleagues, who cooperated in the fraud. The fake fingers enabled six or more fellow doctors to skip night shifts on a regular basis. Ferreira said her supervisor forced her to clock in for the workers and pocketed money generated by the scheme. —D.J.D.