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Q&A: Trump's border wall would face unparalleled construction challenges

ASU expert says workers, housing and materials will have to be transported to remote areas — and then moved during project

Nogales border
March 17, 2017

Hoover and Glen Canyon Dams were engineering marvels built in remote areas, but they had concrete plants and worker housing on site. The transcontinental railroad was built through raw wilderness, but transportation of laborers and materials was simple.

If President Trump’s proposed border wall becomes a reality, it will have none of those things going for it.

The latest news on the wall, one of Trump’s signature campaign promises, is that it will cost an estimated $21.6 billion, according to an internal Department of Homeland Security report.

Trump has asked for $4.1 billion so far in a request to Congress and in the proposed budget released by the White House. “Concept papers” to design and build prototypes were due this month, according to, a website for federal contractors. The field of candidates will be narrowed Monday, and finalists must submit offers with their proposed costs by Friday.

An Arizona State University construction expert says building a wall 1,000 miles long or more — the U.S.-Mexico border is about 1,900 miles — will combine challenges from some of the greatest projects in engineering history. Barzin Mobasher, a professor in the School of Sustainable Engineering and the Built Environment, Ira A. Fulton Schools of Engineering, said workers, housing, support and materials will all have to be transported to remote areas, and then move as the wall is built. Working in extreme summer conditions in remote deserts will present another set of challenges.

To learn more about how it has to happen, ASU Now had a chat with the expert.

Question: Our new president is proposing to build a wall along the border. Is this feasible?

Answer: Anything is feasible. Yes.

Q: What would be some of the issues involved with construction of something like that?

A: You have some preliminary design aspects that one has to address as well as what kind of materials you’re going to use. Is it going to be a fence or is it going to be a solid wall? If it is, what type of material would be used, and what is its life expectancy? You start with those basic questions and move forward. I’m looking at purely from a structural engineering point of view. Of course it’s possible, but what are the hidden costs?

If you were going to build something here in the city of Phoenix, say a 40-story building — a project of real magnitude — you would have a lot of people willing and able to bid on that type of a project simply because you have so many resources here available: ready-mixed concrete producers, steel manufacturers, qualified, certified labor force.

So, mobilization is a major problem. You won’t have a problem with mobilization in a metropolitan area, but if you’re talking about something on the order of a stretch of 2,000 miles — let’s say 1,000 miles — that would require you to be moving. You are building one-story buildings all over downtown Phoenix. That means on a daily or weekly basis all your equipment has to move from one position to another position.

Q: This would be something like building the transcontinental railroad, where you had to move the whole city along with the track.

A: Exactly. Some people have compared the effort to Hoover Dam, for example. But with Hoover Dam they built the entire city and the people would go back to dormitories at the end of the day. … with the railroad tracks, you could use the railroad to move stuff.

Now you can’t use the wall in any redeemable function. It’s different than widening a road where you close one or two lanes and make it operational to some extent and use the same road to bring supplies. The main question is mobilization: How are you going to provide for the people who are going to be working there in terms of the supplies that they need?

How are you going to transport concrete? Let’s say you are doing concrete. What is the closest city with a batch plant? Are you going to move a batch plant? How are you going to take the raw material that is needed for the concrete to some of the roughest terrain, given the temperatures? We all know how hot the temperatures get. You really don’t have the luxury of mixing the concrete and waiting two hours before you can place it. The excessive temperatures we have would make the material set in a very rapid way.

You need to come up with the costs associated. Again, anything is doable, but let me give you an example. In hot weather, concreting people mix in ice to lower the temperature of the rocks and aggregate. Now we need an ice-making plant to make the ice, and you need to get the water there to make that.

So let’s put the idea of using concrete to the side. Let’s make panels. Now we build these panels and take these panels down there one by one. Now you’re talking about transportation along a road that might be a dirt road with these large panels like Lego pieces. They have to be shipped down there, lifted with a crane, and put in place. That’s the picture I want to give you.

It’s doable, but the cost — anyone who says, ‘It’s going to cost this amount,’ I don’t know if all the components are there.

So you say let’s go with steel. Then you have to worry about maintenance and the potential for corrosion and rusting. You’re going to have to figure out the maintenance schedule for this. You’re going to have to have people continuously painting it or galvanizing it. All of these processes are going to be costly, one from the position of mobilization, then construction, and then maintenance. What is the expense of people per mile in this specific region?”

Q: You’d have to build a road along the border first to get vehicles down there.

A: Of course. Now imagine you have 15,000-pound concrete panels to go on a flatbed, 18-wheel truck, and they have to maneuver over those roads. What’s the wear and tear on those trucks? It’s different than moving something from Phoenix to Tucson along I-10. The costs associated with transportation are significant, far more than the costs of the materials you would pay here in Phoenix.

Q: There are existing walls in some spots. There’s one in Cabeza Prieta about 20 feet high and a quarter-mile long, stretching along a pass between two mountains. Actually it’s not a wall; it’s a fence.

A: It’s more than what you see. You have to build a foundation. The foundation would require you to dig 8- to 10-feet deep, so you provide something to secure the concrete. Then you’re going to have to have some kind of anchoring system, so the wall is sitting atop it very well anchored to the foundation. Now the challenge is how are you going to dig a trench 8- to 10-feet deep?

Q: You’d have to blast.

A: You’d have to blast; you’d have to remove the rock; you’d have to make sure it’s consistent in terms of the line. Then you’re going to have to worry about how to fill it with concrete. Now you need fresh concrete on site. You can’t have a pre-cast system.

Any way you look at it, it’s a challenge. But if there’s a will, there’s a way. But then the question is, is it a wise decision? We have so much need for our people in terms of education, health care, job training. Is it money well-spent?

Top photo: Nogales border by Anya Magnuson.

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