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I would like to create a setting where it would have been beneficial to use very large wagons. You are free to choose the setting, cargo and route, within the limitations below. The wagons don’t have to be used everywhere but there needs to be an advantage in using very large wagons rather than many smaller wagons for a particular job.

The setting is an alternate Earth with broadly similar characteristics, although specifics can be changed if it helps. The technology is limited to pre industrial materials and methods. These wagons use animal power, use wheels and have wooden construction with some metal parts. The haulage distance is up to you except it must be a mile or more. The setting needs to be reasonably realistic and may not use magic.

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  • $\begingroup$ Not an answer, but it may interest you to look into the origin of 'juggernaut' $\endgroup$
    – j4nd3r53n
    Oct 3 '20 at 6:24
  • $\begingroup$ @Li Jun - gives a convincing reason for using one big wagon in a comment. He mentions a mongol wagon. If you're moving a big object, you need a big wagon! $\endgroup$ Oct 3 '20 at 10:58
  • $\begingroup$ A major limiting factor is the weight that the wheels and axles can withstand. $\endgroup$
    – Hot Licks
    Oct 4 '20 at 0:12
  • $\begingroup$ @Slarty I have provided an answer a couple of months late which you might find nteresting. $\endgroup$ Dec 13 '20 at 17:55

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There really is no advantage to very large wagons, unless you have some very large cargo to carry. (And then it's not an advantage, but a necessity.)

First, we have to consider just what is meant by "large". There are four factors here: length, width, height, and cargo weight.

Width & height are primarily limited by obstacle clearance, and to some extent by stability. (A tall but narrow vehicle is likely to overturn.) How much effort is needed to make a roadway in your terrain? Forests will require tree clearance, hills and mountains a LOT of earthmoving...

Length is fundamentally limited by turning radius. Here we have the example of railroads. It's not unusual to have a train that is several miles/km in length https://en.wikipedia.org/wiki/Longest_trains but those are made up of individual cars that are about 90 ft/30 m long. Even then, railroad curves are far more gradual than can be found on roads.

Mass is another problem. Unless you have single objects to transport, it's more efficient to divide the cargo into multiple parcels, as for instance with railroad trains hauling coal or ore. But if you do have a single object to carry, your problems are the strength of the wagon itself, and the weight bearing capacity of the underlying surface. Strength seems obvious: you handle the weight bearing by having a sufficient number of wheels (or crawler treads) to distribute the weight over a large area. You can see this in e.g. the trailers used to haul large construction equipment on highways: they will have multiple wheels to distribute the load. Carried to an extreme, you get the crawler-transporters that NASA uses to move rockets: https://en.wikipedia.org/wiki/Crawler-transporter

For some actual historic examples of large wagons, consider the "twenty mule team" wagons used to haul borax ore from Death Valley to processing sites: https://en.wikipedia.org/wiki/Twenty-mule_team Even though the individual wagons were among the largest built, the trains still used two, plus a third tank wagon for water.

PS: WRT the answers claiming that you need a road surface for large wagons, meet the LeTourneau overland trains, the world's largest off-road vehicles: https://en.wikipedia.org/wiki/Overland_train Of course if you're pulling something like this with draft animals, you do need a surface suitable for them to walk on, but that doesn't need to be a hard surfaced road capable of bearing substantial loads.

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As other answers have well said, material strength and power plant capacity and road surfacing will all be key limiting factors. The interesting part of your query is how big can they get?

It's all well and good to shout science! at the top of your voice and limit a waggon to half a ton or so tare weight. This is a reasonable assumption based on Roman engineering superiority as regards roadcraft and wheelwrightmanship.

So, if you want a bigger waggon, you need a bigger animal! It turns out that elephants can indeed be rigged up to haul a pretty big waggon:

enter image description here

I don't know the average height of an Indian of Rewah State when this photo was taken, but anymore is about 5 foot 5 inches. That makes the waggon about fifteen feet high and about twenty feet long and maybe about ten feet wide. A yoke of elephants are pulling it along a graded but unpaved roadway.

For comparison, a 19th century pantechnicon drawn by two horses has what looks like a four foot wheel diameter, is about half the height and 3/4 the length:

enter image description here

Now, if we really want to go big, we need a really big draught animal, along with the engineering to go with. It so happens that there is a world, not so far away from ours, where the happy conjunction of really big draught animals and the roadways and waggons to go with in fact exist. Here we have two Denê individuals, whose heights are approximately seven feet, standing in front of a curundrowacu, which is a large beast of burden. As you can see, he's about fourteen or fifteen feet at the whithers. He's about as big as that Indian waggon we examined earlier.

enter image description here

Here is another image showing the scale, again, of an approximately seven foot tall person, driving one of these mighty curundrowacu, and the large waggon behind. This beast is a little taller, being perhaps sixteen feet. The waggon's wheels are about twelve feet in diameter. They make these waggons to a gauge of about eight feet, and a single lane roadway to handle such a waggon is about twelve feet wide.

enter image description here

As it happens, such beasts as these curundrowacu did in fact live right here on Earth in ages gone by, and we call them indricotheria. As you can see, they outsize an oliphant the way he would outsize a person! If indricotheria & humans lived contemporaneously and we had tamed and domesticated them the way we did with the horse and the ox, I see no reason why you couldn't have mighty waggons thirty or forty foot long with massive axles and wheels, perhaps even doubled the way a large lorry's wheels are.

enter image description here

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    $\begingroup$ wont adding more animal puller can help pull that bigger wagon anyway? the pantechnicon image there seem to show it was pulled by more than two horses, and at least i know that many big wagon is usually pulled by more than single or two animals. $\endgroup$
    – Li Jun
    Oct 2 '20 at 18:01
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    $\begingroup$ Agree with @LiJun - to pull a heavier wagon, you don't necessarily need a bigger animal, you just need more animals. A dog sled, for example, typically has ten or so dogs and can pull several hundred pounds. But you can simply add more dogs to pull more weight - in one record-setting instance, 230 dogs were able to pull a load of over 100,000 lbs. $\endgroup$ Oct 2 '20 at 18:26
  • $\begingroup$ @LiJun -- You can certainly pull a heavier waggon with more horses or more regular waggons. Here's a team of 36 pulling a train of waggons. But keep in mind: those waggons are the size they are because the draught animals we use are basically horse or ox sized! $\endgroup$
    – elemtilas
    Oct 3 '20 at 0:04
  • $\begingroup$ @NuclearWang -- I don't disagree. But in order to invent the bigger waggon in the first place, you need a bigger animal. To put it another way: in the last 2500 years or so, why hasn't anyone in China or Europe or America (especially the US!) made a larger waggon? Basically, it comes down to tradition. Waggons are typically built to the draught animal in question. $\endgroup$
    – elemtilas
    Oct 3 '20 at 0:07
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    $\begingroup$ @LiJun -- Basically, these things come down to tradition. People who have never seen a horse drive cars the size of which are basically dictated by the dimensions of ancient waggons and the animals that drew them when automobiles were first invented. Different traditional animal would, in my opinion, ultimately render a different traditional waggon. And also, the traditional roads and engineering to go with. $\endgroup$
    – elemtilas
    Oct 3 '20 at 19:11
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Taxes

A lot on life is determined by economics. The one behind this one is simple. You pay taxes per wagon. To pay as little as possible, they increase the size of the wagons to transport as many people and goods as possible. Taxes might rise again, which would prompt bigger wagons. As long as the roads can support it, you can grow the wagons pretty large.

Real world examples is in housing. At times taxes were levied on something arbitrary, like the width of the front of the house. You then see houses pop up with very small fronts, that are either very long, high, get wider or a mix of them.

Feeling you want as ginormous wagons as possible, here are some things to keep in mind. What will limit the size is maneuverability, the roads and weight.

The bigger you get, the larger the teams pulling them need to be. This translates mostly in length, which will make them less manoeuvrable. The stress of pulling should be all right, but it'll still wear down whatever they pull with more quickly. That means you'll probably not be able to go into mountains or something similar with huge wagons.

The roads should accommodate this. The wagons likely get wider and longer. This means you need a strong road, capable of carrying the weight so the wagons don't get stuck, especially after a rain. The road should also be wide enough to let at least two pass each other. Otherwise one would need to veer off the road, which would likely result in the wagon be stuck very, very badly if the ground is soft. This would mean a huge investment into large roads everywhere these big wagons would go. A dirt road simply would be insufficient after a certain size. Large roads like what the Romans build is a good start. They made incredibly straight, strong roads with pre-industrial equipment and knowledge.

Lastly the weight. You need to support it all. Wagons can carry a lot, but the larger you get, the more you need to strengthen the structure. This will add further weight on the wheels and axels. The largest I could find in real life were twenty mule team wagons. These could lift up to 30 ton load, but they used a form of train. Essentially each wagon could lift up to 9 metric tonnes. Probably these sizes are still the most practical while still having 4 wheels. Increasing the wheels would probably allow for larger sizes, but this harms their manoeuvrability.

What the size truly would be is hard for me to say, but potentially it could get pretty big on some very straight, strong, big roads between some big cities.

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  • $\begingroup$ Problem with this answer is that taxes are very 'fluid' things. So if enough people start using this trick then the state will be changing the tax. Whilst this could be a good answer in the very beginning when such a tax is instigated, in a setting where everyone is doing it, it would make no sense. $\endgroup$ Dec 13 '20 at 23:06
  • $\begingroup$ @TheShadowOfZama taxes often don't make sense. In some cities in the Netherlands they had a tax on some dimensions of houses. For example, in Amsterdam they had taxes on the width of the houses. That is why most are small, high and deep. They even made multiple houses next to each other and used it as one. In our current times there are plenty of ways for huge businesses can pay less than a percent of taxes. Check what Starbucks pays in Ireland. Or watch how many movies made a profit on paper... If it made sense, there would be billions more tax income overall. $\endgroup$
    – Trioxidane
    Dec 14 '20 at 9:25
  • $\begingroup$ Yeah, whilst I do agree there are a lot of nonsensical taxes, I also know as somebody who lives in Belgium that once enough people start using such a loophole it will be closed. Taxes are made to either rake in tax money or to change people their behavior (for example tax on tobacco). Your example with starbucks tends to not get closed, because it requires international consensus. Same for why cruise ships are still so poluting. Point is I can't see taxes alone explain larger carts. The moment it became popular the tax would be changed. $\endgroup$ Dec 14 '20 at 18:00
  • $\begingroup$ @TheShadowOfZama I understand, but they just don't always close it. It might be seen as unfair, they care less about the law when people start circumventing it or the goal has already been met, which is more taxes than before. And even if the taxes are changed, it could inspire even bigger carts. $\endgroup$
    – Trioxidane
    Dec 14 '20 at 22:27
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The main limiting factor is strength of materials, "powerplant" being the second.

A wagon has all its mass on a few wheels and axis. And when moving (even very slow) expect forces to be twice or thrice of wagon weight!

Since wood is very close in its strength to mammals bones, expect largest wagons made of wood to be the size and weight of elephant. And they really were such used on the Silk Way. With load weight about 2t, total weight about 5t and the size of elephant. With average speed about 2-5 (depending on road quality) kilometers per day.

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The main limiting factor to the size of wagons are:

  • Road surface: if they are moving on loose or wet ground, an excessive load will make the wheels sink. Road paving has been a luxury until recent times.
  • Road layout: in order to allow a large wagon to travel easily, you need to have a conveniently sized road. Narrow curves, steep slopes, narrow road section make for a troublesome or impossible travel. And in most of the recent past easily travelled roads were seen as something to avoid in order to protect the country from invasions. Moreover in agricultural areas a large road would take away ground from farmlands.
  • Power source: if you are limited to animals, to pull a massive wagon you will end up with a very large number of animals pulling it. This either means a very long or a very large pulling set. This again reflects on the need for an adequately sized road.
  • General infrastructure: a large wagon will most surely not fit into the roads of a human settlement bigger than a camp. This would pose an additional burden on the logistic of the transport, due to the additional transfer.

All in all I think the wagons we have seen in our world are the best compromise between all the above listed needs.

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  • $\begingroup$ regarding road surface, this way a key reason behind the development of en.wikipedia.org/wiki/Wagonway a key stepping stone on the development of railways. $\endgroup$ Oct 2 '20 at 19:02
  • $\begingroup$ Adding to the surface and layout, with longer wheelbases if the layout has curves that have too tight a radius, then you will start getting sideslip on some of the wheels, which could break wooden wheels on a muddy surface. $\endgroup$ Oct 2 '20 at 19:10
  • $\begingroup$ Road paving was not a luxury everywhere. When the Humber bridge was built in the UK, the access road on the south side followed the line of the old Roman road, which had remained continuously in use but was not a main route to anywhere. When the old road was dug up for replacement and widening, the stone slabs of the Roman construction were found to be still there after 1900 years. $\endgroup$
    – alephzero
    Oct 3 '20 at 2:13
  • $\begingroup$ You forgot axle and wheel strength, and the ability to lift the cargo onto the giant wagon. The ability to contain grease in the axles might even be a factor. $\endgroup$
    – RonJohn
    Oct 4 '20 at 0:04
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64m wheel-to-wheel. 96m edge to edge

To calculate the largest possible wagon, start with this problem of static equilibrium (as viewed from the rear)

enter image description here

How long can that beam be before the weight of the beam exceeds the breaking strength of the wood? (With a safety margin strong enough to allow for bumps and thumps). We can reinforce it, we can curve the beam, we can split it into triangular trusses, we can do all sorts of engineering to optimise this shape, but we basically end up building a single span wooden bridge.

enter image description here

The largest single span wooden bridge is a tie between Sioux Narrows and Old Blenheim bridges, at "210ft" (64m). These bridges had to withstand wind loads and dynamic stresses similar to what a wagon would experience, so I'm calling the engineering approximately equivariant.

How long your wagon can be is a property of how easy you want it to steer - as you could put 10 sets of wheels on the thing and have it 100s of meters long but be unable to go around corners. (And also - nothing could pull it).

I'd suggest 4 wheel design has good steering. You could theoretically chain multiple together but you'll hit animal power limits

So assuming 64m is the maximum stable single span possible with a wooden structure under dynamic load, we can use that to plan the top of the wagon. A rule of thumb for wooden cantilever design is 1/4 can overhang after a span, so you can overhang your wheels by up to 16m.
enter image description here

I've drawn this as a square, however it may need to be a rounded rectangle so no point on the corner is 16m from the wheel support structure, but this should be a decent approximation.

You have 96m x 96m = 9216 square meters. (-~800 for the rounded corners). Enough for a small village to migrate to fertile farmlands in spring, and seek shelter in warmer climates during winter.

Would also be very defensible - you basically have 50m cliffs around your village. Your archers could rain hell down on an attacking army, and by withdrawing your ladders they will have to try to climb the wheels, and then climb out, up, and over the side. Thick wooden wheels (especially when caked with dried mud like they'll probably be) are going to be very hard for an attacker to ignite.

Animal pulling capacity, wheel design, bearing design, bearing attachment, animal harness attachment layout, etc are all complex problems beyond the scope of my answer, but I don't believe any of them make this design impossible.

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  • $\begingroup$ With appropriate suspension, couldn’t you have support wheels between the outer wheels (e.g. along the center line) as well as more than two pairs of wheels? This way there would be no hard size limit, only the terrain would put a limit on it. $\endgroup$
    – Michael
    Oct 3 '20 at 12:51
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What limits the size of a wagon? Well, the first answer is ratios: A tall-but-narrow wagon is prone to tipping over (especially when exposed to wind), while a long-but-narrow wagon will have an excessive turning circle, so will not corner well.

So, to have a larger wagon, it needs to scale both width and depth. You may have noticed that modern vehicles — cars, vans, trucks and trailers — all have fairly similar widths. Even trains and trams have their wheels approximately the same with apart. Why is this?

Well, the first answer is "that's how wide the roads are". But, why are roads that wide? This goes back to wear, tear, and ruts.

You see, old roads (and you can see this with dirt tracks, or even some cobblestoned roads) would develop grooves, or 'ruts', where the wheels wore away at the ground over time. If your wheels did not match the ruts, you would have a rather rough and bumpy ride, and would risk damage to your wagon and its contents!

But, still, why did so much of the world standardise to the same with of ruts? That goes back to the Romans, prolific road-builders that they were, spreading across most of Europe. Roman roads were ubiquitous, Roman roads were convenient, and Roman roads were used by the Roman army. A notable component of this army was, as it would happen, their chariots. And a Roman chariot was built to be pulled by 2 horses, side-by-side, while remaining as narrow as possible.

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So, a limiting factor in your wagon size is going to be your standard wheel-gage (the width between the wheels). This is going to be determined by dominant early-adopters, who will base it on how many animals they have pulling the wagon/chariot/cart, and how large those animals are. Two elephants side-by-side (or 3 horses) will result in a wider standard gage, which will allow for larger wagons.

Which just goes to show: the size of your train depends on the size of your ass

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Something not mentioned so far is the cube-square law. If you double the size of a wagon in each dimension you will have something 8 times heavier, but the structural members will only have 4 times the cross sectional area, so they will be taking twice the stress (i.e. force per unit of cross section). To compensate you have to make everything much thicker, which in turn increases the weight. This is why an elephant does not look like a scaled-up gazelle.

You are also putting 8 times the weight onto 4 times the ground area, so the wheels will sink into the ground more unless you make them wider too.

Pretty soon you reach a point of diminishing return; scaling up requires thicker wood, which makes it heavier, which means you need stronger members elsewhere, which in turn make it heavier...

The only way to get out of this is to have materials with a better strength to weight ratio ("specific strength"). If your world has some super-wood that does better than oak then you can build bigger carts. Otherwise I'd take real-world carts as a guide; they were built for a lot of purposes, and some of them will have pushed the limits of what could be done with the materials available.

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Here are some examples of large wheeled vehicles.

The following comes from an article in a magazine of Maryland history I read.

The Netherlands established their New Netherland colony along the Hudson River in modern New YOrk in 1614.

The English established a colony called Maryland on both sides of the upper Chesapeake Bay in 1634.

Sweden stablished a small New sweden colony on both sides of the Delaware River in the future Delaware, Pennsylvania, and New Jersey from 1638 to 1655.

The Dutch in the New Netherland colony conquered New sweden in 1655.

English forces captured New Netherland in 1664, but the dutch recaptured it in 1673, and it was returned to England by a treaty in 1674.

So for thirty years the Chesapeake Bay was part of the English colonies of Virginia and Maryland, while the Delaware Bay was part of first Swedish and then Dutch colonies. And trade between those colonies was desired by the colonists but forbidden by law.

Sailing ships with trade goods out the mouth of one bay, along the Atlantic coast, and into the mouth of the other bay would be too flagrant a violation of trade rules, so the secret trade involved carrying cargo across the Delmarva Peninsula. Small ships sailed up creeks as far as they could go, and then were loaded onto giant carts hauled by ox teams and carried to the nearest creeks flowing into the other bay.

The Peloponnese Peninsula in Greece is separated from the mainland by the Gulf of Corinth, except where the narrow Isthmus of Corinth connects it to the mainland. Sailing through the Gulf of Corinth from the Aegean Sea to the Ionian Sea would save a lot of distance sailing around the Peloponnese, but the Isthmus of Corinth is in the way.

Roman Emperor Nero starting digging aon canal through the Isthmus of Corinth in AD 67 but the project was abandoned the next year. A canal through the Isthmus of Corinth was dug in 1882 to 1893.

The Diolkos (Δίολκος, from the Greek dia διά, "across", and holkos ὁλκός, "portage machine"1) was a paved trackway near Corinth in Ancient Greece which enabled boats to be moved overland across the Isthmus of Corinth. The shortcut allowed ancient vessels to avoid the long and dangerous circumnavigation of the Peloponnese peninsula. The phrase "as fast as a Corinthian", penned by the comic playwright Aristophanes, indicates that the trackway was common knowledge and had acquired a reputation for swiftness.2

The main function of the Diolkos was the transfer of goods, although in times of war it also became a preferred means of speeding up naval campaigns. The 6 km (3.7 mi) to 8.5 km (5.3 mi) long roadway was a rudimentary form of railway,3 and operated from c. 600 BC until the middle of the 1st century AD.4 The scale on which the Diolkos combined the two principles of the railway and the overland transport of ships remained unique in antiquity.5

https://en.wikipedia.org/wiki/Diolkos[1]

The Diolkos was a trackway paved with hard limestone[26] with parallel grooves running about 1.60 metres (63 in) apart.[31] The roadway was 3.4 to 6 metres (11 to 20 ft) wide.[26] Since ancient sources tell little about how the ships were hauled across,[24] the mode of ship transport has largely to be reconstructed from the archaeological evidence. The tracks indicate that transport on the Diolkos was done with some sort of wheeled vehicle.[32] Either vessel and cargo were hauled across on separate vehicles, or only the cargo was taken across and reloaded on a different ship at the other side of the Isthmus.[33]

Although a technical analysis has shown that the transport of triremes (25 t, 35 metres (115 ft) long, 5 metres (16 ft) beam), albeit difficult,[34] was technically feasible,[35] it is assumed that the vessels were usually smaller boats rather than ships.[36] To avoid damaging the keel during transport, hypozomata, thick ropes running from bow to stern, to reduce sagging and hogging of the hull,[37] must have been used. Ship and cargo were presumably pulled by men and animals with ropes, tackles[38] and possibly also capstans.[39]

https://en.wikipedia.org/wiki/Diolkos#Track_and_transport[2]

Two other ship trackways are briefly mentioned by ancient writers.

I believe that Alexander the Great or one of his successors had war galleys transported from Syria to Mesopotamia to use in the Persian Gulf.

The city of Constantinople was beseiged many times. In times of seige a large iron chain was placed across the entrance to the bay called the Golden Horn to keep enemy ships from entering.

According to the Russian Primary Chronicle, during the Rus raid on Constantinople in 907:

At this point, Oleg resorted to subterfuge: he effected a landing on the shore and had some 2,000 dugout boats (monoxyla) equipped with wheels. After his boats were thus transformed into vehicles, he led them to the walls of Constantinople and fixed his shield to the gates of the Imperial capital.

https://en.wikipedia.org/wiki/Rus%27_raid_into_Byzantium_(907)[3]

Of course the dughout boats would have been rather small and lightweight.

The big problem with this story is that the Byzantine sources don't mention that war at all. Thus it is suspected that the story of this war is based on the Rus-Byzantine War of 860.

The Golden Horn was also protected by an iron chain across it during the Turkish capture of Constantinople in 1453.

Mehmed ordered the construction of a road of greased logs across Galata on the north side of the Golden Horn, and dragged his ships over the hill, directly into the Golden Horn on 22 April, bypassing the chain barrier.[10]:376

https://en.wikipedia.org/wiki/Fall_of_Constantinople#Siege[4]

It seems rather certain that none of Mehmet II's people had ever read the Russian Primary Chronicle, so they should have thought of it independently.

One answer to this question: https://www.quora.com/Did-the-Ottomans-really-move-ships-over-land-during-the-conquest-of-constantinople[5] mentions other examples.

So there are examples of small by modern standards seagoing ships loaded on large land vehicles, or converted into land vehicles, for comparatively short distances.

And I think that some of the vehicles which carried ships over land may have been larger than the largest wagons mentioned in other questions.

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  • $\begingroup$ So perhaps I should consider wheeled ships! $\endgroup$
    – Slarty
    Dec 13 '20 at 18:23
  • $\begingroup$ @Slarty Maybe. By the way, wind wagons using sails have been built. windwagonproject.se/?page_id=114 At least you should consider that the heaviest ship known to have been moved a distance X shows that a wagon of that weight could be moved distance X with about the same effort. You should also look into methods of land transport of heavy objects like obelisks weighing tens or hundreds of tons. $\endgroup$ Dec 13 '20 at 18:49
  • $\begingroup$ You could have an early version of the standard shipping container. An empire with rails for big wagons, canals for standardized ships, and ports at the end of long, sloped aqueduct-like roads where full wagons rolled down constant slopes and emptied ones were hauled back uphill. Everything uses a standard load on a standard bed. The wagons would be the limiting step, since the water transport could handle large loads better. No loading and reloading, just going from wagon to canal barge to ship and back. $\endgroup$
    – DWKraus
    Dec 13 '20 at 19:44
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Let's start by assuming the main "wagon part" is large. In order to make the wagon work, you need wheels, and some kind of power source.

The upper bound on wagon size is the strength of the wood used to make it. You need axles that can hold the wagon up on the wheels. Let's assume that somehow people got ahold of giant redwoods for the axles and frame. Assuming trees as axles, you'd scale up a standard freight wagon by ~40x. (600ft long, 240ft wide, 280ft diameter wheels)

One big advantage of really large wagons that I can see is that they can just drive over obstacles. (boulder field, who cares?) So maybe there's terrain which is not navigable in a smaller wagon, and the social/political forces prevent building roads. ("Roads? Where we're going, we don't need Roads!")

One issue with all of this is actually moving the thing. You need to find a way to decrease friction (either ball-bearings, which are hard to make, or really good lubrication.) Once friction is dealt with, the speed of the wagon is proportional to the power output of the power source. You have to gear it down a lot, and provide enough lubrication to keep friction to a minimum, but you might be able to do it with the equivalent of hamster wheels for oxen.

Since the wagon is large enough to hold a village, it would probably be a pre-industrial variant of the Jawa sandcrawler from star wars. It moves slowly, due to power constraints, but it's a whole city up there.

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