There are also numerous avenues on how to approach the building of such a wall beyond just the extreme assumptions of building the most expensive variant of proposed walls across the entire border. We can even look to implementation set up in Iraq and Afghanistan for such examples. If you’ll look at my profile picture, you’ll see what are called T-barriers.
Also called Bremer Walls and Jersey Barriers, these are large and freestanding concrete slabs are cheap to build, transport, and install. They essentially fit together like massive Lego bricks with a notch fitting two together that is mirrored on the opposite side so that an infinitely long chain can be created able to bend around objects or buildings and adjust with the terrain that is impossible to destroy without heavy machinery. They’re like legos for big boys.
In Iraq, we used them for two reasons. You can see behind me, that they were lined around our prefabricated living units. This was because the walls were able to absorb the blast of an incoming mortar, small missile, or random rocket-propelled grenade, which might come our way and endanger the thousands of Marines inside. The second way we used them was during the “Surge”, a change in tactics to our counter-insurgency efforts where, overnight, entire city blocks could be quarantined off with these units. This allowed Marines and soldiers to wall off whole neighborhoods within hours, allowing few points of entry and exit that could be manned and checked while teams searched house to house for weapons, contraband, or other signs of enemy activity. Just as quickly, the walls could be moved or removed to clear other parts of the city.
I want to be clear, that like the Great Wall of China example, there is nothing stopping someone determined from getting over one of these walls. A ladder could do it. What they do, however, is prevent the free flow of large numbers of people, and more importantly, a large amount of cargo to pass freely. You might be able to sneak over the wall yourself, and you might even be able to get over with a rifle, but there is no way you are going to be able to sneak an entire team with heavy weapons, rocket and bomb parts, and other logistical considerations over the wall clandestinely. That’s what the T-barriers did. They broke up the enemy’s ability to move and, in my mind, had a major part in the story of how the United States successfully quelled the insurgency around 2007… not that anyone heard about that.
All that to say… I’m a big fan of these simple impediments. They saved a lot of lives.
Even more humble is the HESCO barrier. These ingenious little devices are little more than 21st-century sandbags, literally. They are large canvas bags supported by a metal frame which be broken down and stacked by the hundreds when unused, taken out and unfolded where they will be installed, and then just have sand, dirt, rocks, or anything dumped in them.
Installation of these barriers is even easier than that of the T-barriers requiring little more than two unskilled technicians, a truck, and a lot of dirt.
Importantly, I’ve seen these things stacked four high, making a wall of about twenty feet. Interestingly, it can be filled with dirt excavated in other areas of the construction project. These “insta-forts” are able to be installed, and just as importantly, taken down, in a matter of days, rather than weeks, months, or even years and at a fraction of the cost of what most are assuming such a wall would cost. Granted, this is not a solution that will last a thousand years, but it will get the job done in many of the areas where a massive wall isn’t required, but some impediment is.
This is why the same technology (yes giant bags of sand and dirt still count as technology) is used in the United States civilian side to protect against the sudden threat of flooding.