Is it feasible to build a wall between the US and Mexico as Donald Trump claims he would do?

(March 19, 2016 )

A structural engineer did an analysis of what it would take to build Trump's wall.
Here is a link to the article (design drawings, calculations included):
An Engineer Explains Why Trump's Wall Is So Implausible

  • Human beings have built a 2,000-mile-long frontier wall exactly one time. Once. And it was accomplished only through a centuries-long building campaign that necessitated the forced labor of millions of Chinese peasants.

  • A successful border wall must be effective, cheap, and easily maintained. It should be built from readily available materials and should take advantage of the capabilities of the existing labor force.

  • The wall should reach about five feet underground to deter tunneling, and should terminate about 20 feet above grade to deter climbing.

  • The barrier must also be a continuous, non-porous construction. This distinction might seem purely semantic, but Trump has made himself very clear on the matter, 'saying' “A wall is better than fencing, and it’s much more powerful. It’s more secure.  [The engineer then rules out cinder block, wire mesh and other materials for various maintenance and labor cost reasons and settles on a concrete wall as the solution]
  • There are two major types of concrete construction: cast-in-place, where wet, plastic concrete is brought in trucks to a job site, cast into formwork, and then cured; and pre-cast concrete, where the concrete is cast in a controlled indoor environment, cured, and then shipped to the construction site for assembly.
  • The hot, dry climate in the border regions would complicate cast-in-place construction because high heat tends to screw up the chemical reactions that cause concrete to harden.
  • If we assume a border wall length of 1,954 miles (there are 600 or so miles of existing border barrier, but much of this would not qualify for Trump’s wall), then we can make some estimates as to the volume of concrete needed for the project:
Foundation: [author provides underlying calculations] yielding:
  • Twelve million, six hundred thousand cubic yards. In other words, this wall would contain over three times the amount of concrete used to build the Hoover Dam — a project that, unlike Trump’s wall, has qualitative, verifiable economic benefits.
  • Concrete, of course, requires reinforcing steel (or rebar). A reasonable estimate for the amount of rebar would be about 3 percent of the total wall size, resulting in a steel volume of 10,190,000 cubic feet, or about 5 billion pounds. We could melt down 4 of our Nimitz-class aircraft carriers and would probably be a few cruisers short of having enough steel.
  • All of these hundreds of miles of wall would need to be cast in concrete facilities, probably project-specific ones that have been custom built near the border.
  • Then, the pre-cast wall pieces would need to be shipped by truck through the inhospitable, often roadless desert.
  • The men and women doing the work of actually installing the wall would have to be provided with food, water, shelter, lavatory facilities, safety equipment, transportation, and medical care, and would sometimes be miles away from a population center of any size. Sure, some people would be willing to to do the work, but at what price? Would Trump hire Mexicans?
  • This analysis also ignores the less sexy aspects of large-scale
  • engineering projects: surveying, land acquisition, environmental review, geological studies, maintenance, excavating for foundations, and so on.

  • Theoretical President Trump may be able to executive-order his way through the laser grid of lawsuits that normally impede this kind of work,but he can’t ignore the physical realities of construction.
  • Trump’s border wall is not impossible, but it would certainly be a more challenging endeavor than he would ever lead you to believe.
I wish that the voting population would do more thinking and analysis of such proposals and only then make decisions about who to believe & elect.

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