Let us they need to be double walls. This way when they climb the outer wall an alarm can be triggered and we can arrest them before they finish climbing the second wall.
That is what Customs and Border Protection wants in the Urban areas - a double barrier with an "enforcement zone" in between that is lighted at night, and wired with sensors and cameras.
I can see drones chasing their little as*** back to whence they came.
Definitely double walls. That way there is a road in between them. Plenty of ways to use that. Not just for capture but also for upkeep, updating, testing various methods....I have no clue about all of the logisitics but the double fence seems like a no-brainer.
Looking at the top of the walls. Any that are flat or angled outwards can be scaled by use of grafting hooks. By the round top ones offer, No support for the hooks to grab on to.
Just my two cents.
It is what happens after they are arrested that matters. Intel the risk is greater than the reward they will keep coming, wall or no wall.