Just like with the wall a tunnel underneath makes them useless, and a new ladder to get over makes them worthless. You could even blow a hole in them with an acetylene torch. Sure someone could be right there to patrol the area. But anyone who has traveled 1000 miles or more is not going to let anything stop their dream of a better life deter them. That's why to slow down these people you actually have to put forth some intelligent immigration reforms. Lastly America needs these immigrants, they work hard, do jobs that many do not want, and most come so their children can get a better education and a better life.