Blue
Prior to drones equipped with heat sensing long range cameras walls may have been less effective.
As it stands, the problem with a tunnel is that it must rise somewhere and with today's audio and video technology, digging tunnels secretly ain't very easy.
Without having to physically patrol areas on foot, drones can patrol the wall and pick up heat signatures.
They can average out amounts of heat traffic and quite easy determine where tunnels come up.
So you might say, they could use one tunnel with numerous exits. The problem there is that if one exit is discovered then the entire network is shut down.
Also, as yourself you might know, solids are the best sound conductors known. Placing listening devices at intervals along the wall would pretty much make it impossible to dig without being detected. Again, an unmanned bit of tech.
Nevermind digging, just walking through a tunnel, even if it's a few hundred meters below ground would be relatively easy to detect. Combining that with software that is set to recognise various sounds and patterns makes illegal crossing through tunnels very close to impossible.
Finally, narrowing down routes into the US to tunnel systems makes the entire process of getting across the border illegally a lot more tricky.
What's is more likely to happen is that they'll go over it.
A case of spend tons of money and time on something that will immediately be useless once discovered versus using quickly erected scaffolding, ladders and ropes...the choice is pretty obvious.
With a team of four guys, I'm confident that I can erect 5 stories of single column scaffolding in about five minutes.
I don't know how the wall is going to look but I'm sure going over it will be a lot easier.
Also, going straight through it might not be that difficult either. A few well located blast holes and some explosives might do the job. Obviously diversions might be required haha
Haha anyone know where I can apply to "test the wall"?