How to build roads in a windy desert

Question

The world is a desert, and it's awfully windy. The wind is as unpredictable as possible with an average speed around 150km/h. It's usual to see wind reaching 300km/h once every three days.

The human civilisation has grown in protected areas to become cities or villages. They have water, wood, food, livestock, but no motor. Few people have crossed the desert from one city to another and even fewer made a fortune by bringing back unknown goods.

I'm already rich but I want more by starting a business selling goods between cities. How do I secure the transport between city A and B?

1. I want to protect the goods
2. I want to be able to grow my business to a big scale
3. I don't want my potential employees to betray me

The idea for this question came to me from the french book La horde du contrevent

Answer 1

I would consider it to be a very controversial topic. On the scale of ships ramming at high speed in the Star Wars universe. And you will probably not like my answer.

When you add a particular part in a world, you need to take into account how it can be utilized by people.

Currently wind speed that is considered to be economically viable is about 25 km/h. Wind energy per area grows as speed^3. At 150 km/h energy per area is 200 times more. And economical viability is very strongly correlated with this energy per area.

You may say that wind speed is too high for our existing sails, designed for our weak wind of 25 km/h. But lets consider this, when did we make our first tech that was able to reach 150 km/h? Probably tens of thousands of years ago, with a bow. We added feathers to the arrow, thus creating a mechanism that operated at such speeds. Using extremely primitive tools and materials and while being restricted by weight. You may say that it doesnt count, arrow isnt really using the wind, just tolerates it. Then lets consider more modern example, a plane. It can fly at speeds of much higher than the wind speeds in your world. You may say that it is too modern to exist in your world.

But here is my main point: we did not suddenly invent the wing when we were able to manufacture the parts needed for the flight control. Arrow's tail is a wing just as much as plane's wing is. Idea behind it is primitive, and there is no need for controlled flight in your world, no need for all of that complexity.

The only reason that we did not use the wing earlier is that we had no use for it. Our tech didnt allow to use the wind economically, because of how little energy in the wind we have.

What would we do if we would have such winds? We would build wings from stronger materials. Material strength is really a non-issue for a wind, we knew metals for thousands of years. The only reason we used weak materials for our sails on ships is because of the weight requirement, ease of use, and lack of need for stronger material. Why use more if you can use less?

Lets consider a sword. We made them thousands of years ago. And it is sufficiently close in shape to a wing to be used as is, even better if some thought to optimise it would be used. Yes. Full metal wing is what im leading to. Because why not? What can stop a person from doing so? lack of metals in a desert? Thats where I consider author didnt think through his plan again.

Sand is eroded material, mostly silicone, aluminium and iron, in a form of oxides. Lots of other elements as well. But this is enough. Magnetism is known for thousands of years as well. And sand that is flying over you is just an amazing source of iron. All what you need to do is to stick some magnetic piece out for a second, and iron oxide dust will stick to it, and wind will carry away all the non-magnetic particles, thus doing all the mining and refining for you for free! I cant even imagine a world where it would be easier, even in theory.

Currently there is a few percents of iron in sand. It is a lot. Even if you try to explain it away with extremely low iron content, the ease of mining completely negates it. Even at parts per million, that would make you rewrite the whole stars and biological evolution, people will still be able to mine it due to ease of magnetic filtering in a sand storm.

Now, what can you do, having almost infinite amount of energy from a full metal wings and almost infinite amount of iron oxide from the magnetic filtering? Well, you use it to close the production loop.

We didnt use magnets for motors for so long because we didnt really have much experience with quickly spinning things and magnets together. Our first quickly spinning thing was probably a steam toy from Greece, but there was no magnets nearby at that moment. Still that shows that our metallurgy was ready even back then. And then for thousands of years our spinning things that we actually used a lot were too slow for a magnet in them to do any useful work. Electric motors power per edge speed grows as speed^2, so fast speed is necessary to notice or use it.

Having a whole civilization built around quickly spinning things for early work mechanisation, and being constantly exposed to magnetic dust makes the chances for them to discover the path I am describing almost inevitable.

So, what do I offer? I offer to use a car with a metal wing if tech is low. We have those today for a beach and desert racing. It doesnt have moving parts other than wheels and, ideally, a turning sail that looks like a fish's fin. We have known wheels for thousands of years too. And a blacksmith can make the wing. Either as one large piece or as segmented armor, riveted together. This idea operates by extracting the work from the speed difference of the sand and wind. Doesnt matter how weak the sand is as a basis, you always can make wheels pressure less by making them bigger, and counteract wind's pressure by making the body more streamlined and heavier. All the way to the sand ship if necessary. Yes, a full metal sand ship. With metal sail.

wind car

More high tech version would have a large metal propeller, like planes do, and will use the energy internally for movement and other uses. By high tech I mean more than one blacksmith per habitat.

There is no such thing as too much wind, as long as you have a habitat intact, more wind is always better. After all, you literally have a WW2 plane's engine worth of free power in every piece of metal you find or make.

What I am describing is ridiculous. I am not arguing that. But that is the consequences of importing a world changing effects.

I've checked pictures, author draws some ridiculous flying devices with transparent wings, that would be eroded in sand storm instantly. Or would cause extreme load on anchors to not to fly away. Or has to spend extreme amount of energy to fly against the wind with no anchors. And is extremely limited by weight and complexity to keep it flying. I see no use in those. Also people walking by foot at few km/h, where a solid sail would ride at 100km/h is also ridiculous.

Energy in speed difference of wind and sand is extreme and has to be utilized. No reason to fly - cant extract the power this way. Same for boring underground, no energy there either.

Even Avatar's sand people are described better, with their sand vessels. Those would work for extremely low tech, before metallurgy, at tech level of 5000 years ago or so. A wooden sled with a sail, wooden sail in your case.

Sand people

Answer 2

Unless you want to deal the wind speeds slightly down, the only solution I see is to build massive sloped berms on both sides of the road to serve as a windbreak (massive like in several tens of meters in height and more then hundred of meters in width, maybe more). Since that is a desert, you do not have a possibility to reinforce those berms with trees and plants. So you would need to use stone blocks or cement to build them.

In general, it seems more like a civilization-wide effort along the lines of Egyptian pyramids or Great Chinese wall, than a fast-profit business venture. It will also need constant maintenance and repair. Manned stations at certain intervals with people being always ready to clean the sand blockages, install and take down temporary screens, etc.

Another idea that may work is a huge 'crawler'. A huge tortoise-like shape, much to massive to be affected by the wind, similar to a medieval siege engine, but several times bigger. Huge wheels, hidden under the shell, a huge number of oxen or similar animals to push it from inside, storage area for the cargo and people. A rocket equation problem comes in play here - whether the oxen are able to move the weight of the shell, cargo, people AND feed for themselves enough to go from one settlement to the next one.

UPD: What I think will NOT work:

• Lighter screens of any type, similar to windbreaks along our automotive roads. I can't imagine a lightweight material that wouldn't just sail away in such a wind.

• Tunnels. Creating a tunnel under the shifting sand in what is, effectively, a constant sandstorm doesn't seem a safe proposition to me. Not only the pressures on the ceiling would be constantly changing, you will also not be able to create a reliable ventilation system for it. Any sort of ventilation channels would get clogged with sand all the time.

• Sailing. The speeds you mention are several times higher then the speeds deemed safe for sailing at sea.

Answer 3

To protect roads against harmful winds:

• Install windbreaks or shelterbelts along the main roads:

  
  ^source

• Alternatively walls could be used, but they are a lot more cost-intensive.

  The big question usually is who is going to construct and maintain these options, but since it will benefit the economies of all connected participants, it will probably be a profitable investment.

For the individual solution:

• You can also opt to use all that wind power:

  
  ^{source (video)}

  You might need something a little more sturdy to withstand the winds in your world, but the principle could be lucrative, if the winds prove to be somewhat reliable.

Answer 4

If the winds are predictable (to a point) you can try to dig in out int he wild when travelling (and dig yourself out afterwards). Possibly by adding windbreaks to catch blowing sand before it covers your position or by setting yourself up to get covered by sand and having enough air to dig yourself out. Ideally you would travel from safe area to safe area. A desert doesn't have to be dunes, it can contain rock. It could containman-made rocky outcrops like a fort or a large artificial cavern.

If the wind direction is predictable you can have the entrance/exit face a favourable way (allowing ventilation and exiting). If the wind changes day by day having multiple exits (with the open exit changing depending on the wind). it would be a job to uncover the exits every day but with at least 1 exit open at all times.

This would give you small settlements/outposts that need to be manned similarly to stage coaches. They could be supplied (and keep supplies for the return journey) allowing the trader to move much more freely. It is much easier to travel if you're not carrying food and water for yourself, your animals and the return trip.

It might also be good to have navigation mirrors up that reflect the sun. Like a lighthouse. They may need to be defenses against marauders or local animals depending on your world.

If the civilization is old it can be that once it was full of these posts but they have gone into decay. Perhaps some quite impressive old ruins are still in use. If it's an emergent civilization then it could be that they just started building these and the problems that show up (animals, buried, unexpected wind shifts, rains of fish) are still to be encountered.

supply to these posts could be done by a separate entity (this will mean they will charge a toll for people staying) or by themselves (in which case they likely will charge rent for room and board individually).

Perhaps overland travel is being done these days and it is inefficient but one rich trader has read stories of underground tunnels in the rock and is exploring for one of these as it would be very fast indeed and it will mean they don't have to pay a toll. Also they may encounter weird things from the past, unleash an ancient evil, activate ancient machinery or bring about a new age of enlightenment as trade and therefor culture can take a leap

Answer 5

Sheltered above-ground walkways

People have been building large stone structures for a very long time. If these people have access to stone, the most straightforward answer is probably for them to build sheltered walkways above ground. If stone is not abundant, but they have sand and water, I'd expect them to make bricks (although bricks will probably wear down faster).

These walkways would be built outward from this town toward the next. It might take a long time for walkway construction to reach the next town, but each step of the way is protected by the hallway that's been built up to that point. It will go faster if both towns are able to build toward each other.

If this is a sandy desert, I imagine that the hallways would eventually be covered by sand. This is a good thing, because it protects the structure from the wind. However, it does mean you have to worry about too much weight. For this reason, I would expect covered exits on the leeward side at regular intervals so that staff could climb up top and remove excess sand, and sweep out sand that has gotten into the tunnel.

Tunnel security will be a major concern as thieves seek to prey on shipping. As the Greeks said, "Where there is a sea, there are pirates." I would expect thieves to lurk in the desert near the maintenance exits that are far from town so they can ambush traders. I think this will be worse than historical piracy in the real world (e.g. along the Silk Road), because the only navigable routes in this world are so discrete. So, nobody will build these walkways until they have devised a business model that provides for adequate security. (My guess is that this would have to include a mix of armed escorts, patrols of the walkways, and well-defended security checkpoints at each terminus.)

Answer 6

I could imagine a ship-like means of transportation in combination with an underground fluidized air bed. (As it can be seen in this video by Mark Rober: https://www.youtube.com/watch?v=My4RA5I0FKs)

If the sand is not static but fluid it would somewhat behave like water and you could technically use specialized sand ships on the fluid sand road.

This - of course - is a huge technical undertaking as it would require every road to have a fluidized air bed. But maybe there are natural ways to induce this by reconnecting underground tunnels. You could use wind power to your advantage if you are able to redirect it underground and then let it blow back up and fluidize the sand. In combination with the sails of the sand ships and the already strong wind this could be possible.