Not that I feel the wall should be going up, BUT, if it's to be constructed then why spend a lot of money when you don't need to?
The wall design I propose here is very inexpensive, easily repaired, offers storage space for the Patrol, and offers a surface on top where as the Border Patrol can actually Patrol the wall in a vehicle, be it a normal vehicle or an ATV.
My design utilizes Shipping Containers filled with OLD Tires and dirt. OR, any other materials that are available and hard to dispose of. Of course, nothing that has Radioactive Materials, explosives, or hazardous materials. If not dirt then things like used Tires, plastic, and any other difficult to dispose of materials however can be used. Just lock it away with dirt inside each container.
As for Patrolling on top of the wall. A roadway might be considered, or just something poured on top of the wall that offers a stable yet smoother surface for the vehicles that might be used to patrol it. If given the option, I would propose using Solar Roadways (SolarRoadways.com) so that the wall can also be a generator of energy.
As for safety for the top, on each side of the wall a barrier could be put as well to reduce the chance of a vehicle driving off the side. Or, perhaps even some kind of track system instead of a road whereas greater speeds could be achieved? The options for the TOP of the wall AFTER the wall is constructed are endless. Heck who knows. Perhaps even a HYPER LOOP TUNNEL could be put internally?
The Standard Width of a Military Jeep is less than 7 feet wide (approximately 6.6 inches). The standard width of a Shipping Container is 8 feet wide. So if two containers were to be used for the wall Width, it would provide 16 Feet Width for the top giving nearly 2 additional feet for two vehicles to pass. I personally would recommend using ATV's instead of a Jeep. An ATV is about 4 feet wide. Thus two ATV's could travers the top back and forth with no issue. Additionally, if the two container wide option is chosen, then a standard Jeep could traverse it back and forth as well BUT the drivers would have to slow down dramatically when approaching each other due to lack of passing space. Of course, another option would be to add additional containers at key points where as the jeeps could then have those locations as their passing points. Add a barrier on the Left and right (Welded or bolted) to reduce driving off the edge of course.
Standard ISO shipping containers are 8ft (2.43m) wide, 8.5ft (2.59m) high and come in two lengths; 20ft (6.06m) and 40ft (12.2m). Extra tall shipping containers called high-cube containers are available at 9.5ft (2.89m) high in case you wanted your wall to be higher.
The Border of the USA and Mexico is a bit under 2000 miles long. As we know, 5280 feet equals one mile. If using 40 foot long Containers, we are looking at needing to cover 10,560,000 feet. So, 10,560,000 / 40 = 264,000 Containers. The average cost for a 40 foot long container is about $2500.00. I would expect a volume discount when ordering nearly 300k containers. So I am going to go with a guess of say 10% discount minimum. We will go with 300k containers to permit for wide areas for potential passing if Jeeps are used. So 300k x 2250.00 = $675m. So for less than $700m we could have an 8 foot tall by 8 foot wide Wall.
Now of course, if we want it to be 16 x 16, then the cost is x4 ($2.7B). The double width would of course be much higher AND offer patrolling space for ATV's to travel in both directions (or Jeeps).
Logically I have not factored in the cost for Labor for filling and placing the Containers but using standard methods for dirt excavation put in reverse to fill each container then set it, the cost should not be too exceptionally high.
For your viewing pleasure, I have also provided some images for an even more elaborate wall as funds become more available.
