The time of my story is about 100 years from now. between 2020-30 a huge war started which lasted a few decades. At the end of the war, America decides to divide into 3 nations (at least), all having different laws and leaders (i'll have at least one nation being republic). I want a nice big wall to separate the nations. But would it actually be possible to build a huge wall stretching across America? I've thought about only having the richest nation having a wall, so that they're cut off from everyone else. Bear in mind that there would've been thousands of builders working on the wall.
Well, the pyramids at Giza are beleived to have taken something like 50 years to build and the Great Wall over 2000. I don't know what the offset would be when comparing modern building technology against the fact that when these other great structures were erected in the past, you didn't have to be nice to the workers (a.k.a slave labor, forced labor, etc.) Is it possible to push your story timeline a little further out? One thing science fiction stories often get wrong is using a 'when' that is only decades away and paints a world that is fantastically different. In the 1950s, everyone envisioned a 'near future' where we would have paperless offices, flying cars, we would wear slick silver jumpers because they're oh-so spacie. We still live lives that someone from 1950 would recognize as rather normal. Yeah, cellphones and tablets and laptops, but we still drive cars that are cars, we still go school where there are live human teachers. Life has progressed, but the paradigm remains the same.
What? You're not wearing your slick silver jumper? Isn't there already a 2000KM wall/fence between USA and Mexico? Research how long this took, the materials used, the labour used and the unions controlling the builders. Did they enforce strict 40 hour weeks? Will you? Will your wall be built by slaves? Union controlled workers? Free labour? How many builders will you have? I don't think any reader will question your stats, 200,000 men building 10,000KM of fence in 50 years - flower it up a bit and you're sweat.
I have a big wall in my future world and my critique group suggested I make it more futuristic than a 'wall'. Have you considered alternative barriers? Some laser-forcefield combo, burns anyone up that tries to cross? What function does the wall serve, because people could fly over it, couldn't they? Think function and design your barrier with that in mind. The time to build it is flexible. More workers, machines, things could move as fast as you want.
Have you considered doing it like the DMZ in Korea with fencing, minefields and guard towers? Would take less time, take less people to build it, cost less and likely be more secure as well. Certainly if you have the option of making the fence more than one layer and electrified for example. However you did it I'm not sure if you could do it in your timeframe, as America is so big and cutting it off into three parts would take an enormous amount of people and time I would think. I guess if you had unlimited manpower it might be possible. As nothing on that scale has been done recently and as you don't really have to say how many people you use to make it happen you could get away with it in a work of fiction no matter which way you go with it.
A few miles from me, they are repairing and resurfacing an eighty foot span, an overpass at an on-ramp to a toll road. So it's a State project, also known as a "career." So completing a project like you are describing shouldn't require more than a couple millennia, assuming government rigor bureacratis doesn't get much worse.
It's not impossible, but I agree with Cogito that it would probably take hundreds of years to complete a project like that (even with out the rigor bureacratis). It would be almost impossible. The materials involved alone would be pretty mind blowing. Eradicating slave labour kind of brought an end to the feasibility of mega-projects.
The last version of the Berlin Wall (concrete) took approximately five years to build. The Berlin Wall was about 87 miles long in total. But as others have mentioned, it all depends on design, personnel, equipment, and also the land it's actually on. Building a wall across Nebraska would be a piece of cake; building it across the Rockies would be a whole 'nother story.
I was also thinking about the Berlin Wall. Like everyone else has said the time it takes is highly dependent on the labor and resources available. This is also a good point to consider.
It could be done. It would be famously expensive. Look into Israel's current solution to the Palestinian issue, or the Berlin Wall, or the Great Wall of China. These sorts of partitions can be done.
Well first let's dispel some historical myths. One, the great pyramids did not use much slave labor. If any. Many of the works that built them were part of the tithe owed the rulers of Egypt. Those workers were professionals that were well fed and cared for, not watched at all hours by an army. We like to look back at the achievements of the past and say they used inhumane methods to construct those wonders when it mostly involved devotion to a cause, time, and more skill than we give our "savage" ancestors credit for. Two and more important to the topic at hand, the Great Wall of China was DOZENS of projects spanning centuries that were eventually joined together/expanded into a single structure. They were not all built at once and you can see a great variety of materials used in their construction. And many parts (particularly those high in mountains that can not be reached easily) are quite thin. Some parts used slave labor (prisoners of war typically) that ended up buried nearby or sometimes under the structure. Many used paid workforces. Why not use something similar, with the nation's taking the ravaged road/overpass network and building them up into walls. Why start from scratch when you can reinforce/expand what is already there for half the cost? Or just wave your hands and say magic...I mean nanotechnology did it.
The DMZ between North and South Korea and the walls and fences that Israel have built are great points of research. I don't know much about the DMZ, but Israel's walls and fences had been in planning stages for decades prior to any construction. Even in Israel, those walls are expensive. Purchasing land and rerouting where people owned land that refused to sell caused extremely long delays. Most of the security barrier is fencing with virtual monitoring; only a tiny portion is concrete wall (in places where snipers were murdering civilians) and the rest requires advanced technology to monitor. Terrorists have dug under, climbed over and cut through the fence on several occasions. The security barrier hasn't even been finished in the South yet due to the cost and lack of terrorist attacks originating from Judea.
If we're talking future, why not go full sci-fi? A hypothetical super-strong wire built with nanotechnology could retain its stiffness without a secondary anchor point. Deployed by rockets, the "wall" could be built in no time at all and be impervious to the passage of ground or air vehicles. Combine that with motion sensors and regular patrols by motorized infantry and you've got an airtight border without the investment of time and labor costs.
I think it was supposed to be more on the order of 1100KM, and it's a fence, and I don't think it's actually been completed, yet. Most intelligent people I know consider it to be a really, incredibly stupid idea (show me a ten foot high fence and I'll show you an eleven foot high ladder). Which leads me to my basic question: of what possible use would a wall be in a futuristic society (unless your story is of the post-apocalyptic-return-to-the-stone-age variety)?
If I were a civilization that existed a century from now, I would construct a barrier which bent the physical dimensions back upon themselves by that anything traversing the barrier would find its course suddenly reversed rendering the barrier impenitrable. I would call it a dimensional mirror and amuse myself by hurling cream pies at it so they they would hit me in the face and I could eat them at high velocity. This, perhaps, woud be too whimsical for your story I fear.
"But before I built a dimensional mirror I'd ask to know What I was mirroring in or mirroring out..." (apologies to Robert Frost)
How futuristic are we talking here? You could have a "force-wall", which, aside from a few "force projector posts" would not require much building at all.
Consider something along the lines of a futuristic world (I'm assuming you meant 2120 - 2130 since you said it would take place about 100 years in the future, right?) So I look at the development of technology and the likely growth of various sciences. What I foresee is the invisible fence of the future. Or you may prefer a light fence if you want a visible barricade beaming an electronic charge across massive expanses of land; perhaps not strong enough to kill anyone violating the space (unless you wanted that dastardly effect), but certainly enough to make them think twice before daring to attempt breeching the wall a second time. With modern technology, something of this nature would take very little time at all. If you are looking to the future, you must look beyond the present. And that includes the technologies of the present as well. If an electronic fence can keep your Lhasa Apso in why can it not, with certain variations, keep intruders out?
There is a machine with a virtual fence that does nothing but destroy female mosquitoes that try to enter your yard with a laser. Yes, this exists today. You could probably extend that technology to people in 20 or 30 years time.
Think outside the box. First of all, your dates are wrong 2030 is only 17 years from now. I think you meant to put 2130. By then, we'll have better technology. Make a force field wall projected by "beaming stations" that are set 20 - 50 miles apart. Each station could be 300-500 feet tall and send out an invisible force field that spans out 10 - 25 miles wide and 100 ft tall in each direction.
Personally, I'd opt for a forcefield. But a wall is plausible, you just have to convince the reader. Half the job is if you yourself are convinced. Whatever you state as a fact, with confidence, the reader will go along because they want the story to work, they want to be entertained.
