The Department of Homeland Security canceled a project to build a technology-based “virtual fence” across the Southwest border, saying that the effort was ineffective and too costly.

DHS Secretary Janet Napolitano  said she had decided to end the five-year-old project, known as SBI-Net, because it “does not meet current standards for viability and cost effectiveness.” In a statement, Napolitano said border agents would instead use less expensive technology that is already part of their surveillance equipment, tailoring it to the specific terrain where they will be scouting for illegal border crossers and drug traffickers.

Napolitano said she had concluded that the original concept of the project, to develop a single technology that could be used across the entire border, was not viable. Boeing had built a complex system of sensors, radars and cameras mounted on towers that was supposed to lead border agents to the exact location of illegal crossers. But the system reportedly functioned inconsistently in the rough terrain along much of the border.

The project was originally estimated to cost more than $7 billion.