I posted down below as well, but I think wind is going to be a big issue for them. A 170km long, 500m tall wall is about the least aerodynamic thing I can think of. I would anticipate that wind issues will be substantial.
My napkin math said that if peak wind speeds hit it dead on, the wind will impart a force of 156N/m^2. A 1 meter wide slice will have to absorb roughly the force of 3 Tesla Model S' pushing on it at full throttle. Across the entire wall, the force is roughly equal to that generated by 381 Saturn V rockets at lift-off.
The other problem is price; they're almost certainly off by at least a couple orders of magnitude. The Burj Rafal is 308m tall with a 20,000m^2 base, and cost $320m, which comes out to $520/m^3. $500bn for this comes out to $29.41/m^3. That price for the Burj Rafal probably doesn't include public infrastructure (electricity generation, water cleaning, sewers, etc), and Neom will be way too big to piggyback on an existing system.
It's a neat idea, I agree I hope they build it, but I hope they do so cautiously. Build a kilometer or three and then revisit the design and costs. Starting with a 170km version of it almost assures that it never actually gets finished.
My napkin math said that if peak wind speeds hit it dead on, the wind will impart a force of 156N/m^2. A 1 meter wide slice will have to absorb roughly the force of 3 Tesla Model S' pushing on it at full throttle. Across the entire wall, the force is roughly equal to that generated by 381 Saturn V rockets at lift-off.
The other problem is price; they're almost certainly off by at least a couple orders of magnitude. The Burj Rafal is 308m tall with a 20,000m^2 base, and cost $320m, which comes out to $520/m^3. $500bn for this comes out to $29.41/m^3. That price for the Burj Rafal probably doesn't include public infrastructure (electricity generation, water cleaning, sewers, etc), and Neom will be way too big to piggyback on an existing system.
It's a neat idea, I agree I hope they build it, but I hope they do so cautiously. Build a kilometer or three and then revisit the design and costs. Starting with a 170km version of it almost assures that it never actually gets finished.