How would a `smart wall´ work at the U.S.-Mexico border?
(LA Times MLB)

Deep in the Otay Mountain Wilderness, there is no wall. The only boundary between the U.S. and Mexico is a section of barbed wire fence in a pastoral valley. And miles and miles of treacherous terrain. It´s a territory crisscrossed by steep trails that disappear into tunnels of thick brush, a place...