Ground radar and cameras that were to identify illegal border crossers so that armed patrols could be dispatched to capture them have had trouble distinguishing people and vehicles from cows and bushes. The sensors are also confused by moisture, the officials said.
The government is also holding back $5 million in payments to Boeing Co., in an attempt to hold the company's feet to the fire. DHS's original plan was to spend $2.5 billion to secure 370 miles.
Even on a relatively thin 28-mile slice of the border, cameras are having difficulty with automatic-focus software. Radars needed continual fine-tuning to "de-clutter" their returns. Moisture from this year's heavy rain unexpectedly blurred sensor images like water on a windshield, officials said. The wild region's deep canyons and thick vegetation have further complicated the cameras' performance as well as the tower's power supply and communications.
"What they always find is the real world is harder than the laboratory. You get out there, it's hot, there's sand -- it just takes a while to work through," said James A. Lewis, director of the technology and public policy program at the Center for Strategic and International Studies.