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Suppose, for a moment, that there is a human inhabited supercontinent. The planet that this supercontinent is on does not have any large landmasses which are more than 10 KM from the primary continent (at the closest point). Realistically, there may be some islands a bit further away; assume for the time being that they are of only minor economic importance.

The perimeter of the supercontinent is roughly 40,000 km in length. Assume it is roughly circular for the time being.

The total land area is similar to that on earth, but due to it's arrangement, considerably less of the available land is habitable to humans.

Since it is difficult for rain to travel across vast distances, the interior of this super continent will be a massive desert, meaning human habitation will be concentrated on the perimeter of the continent.

For much of history, shipping and travel would be done via boat, sailing on the supercontinent's edge; it's probably faster than driving horse carts around the edge of the continent.

Now, suppose someone builds a large railroad which spans the entire perimeter of the supercontinent. In addition, rail bridges or underground tunnels are built to reach any landmasses close enough to the main body of the continent for the construction to be feasible. This railroad has at least four lines that all completely encircle the supercontinent; two or more in each direction.

This railroad will be built during the steam era; it will initially not be possible to build long routes through the interior desert, but as technology improves, it will be possible to build longer and longer “shortcuts” through the arid continent interior.

In this case, are oceangoing ships now doomed to be used only to ferry goods and passengers to and from the various small islands that dot the edge of the supercontinent? Or are ocean going ships still competitively viable on routes from one part of the supercontinent to another?


Bonus: In a scenario like this, is it economically feasible that airplanes or airships will become common, or will economics force them to be a niche form of transportation, used only by the ultra wealthy?

does this calculation change if, later in this civilization's history, they manage to build railroad tracks cutting through the center of the interior desert, meaning that trains traveling from one side of the continent to the other can take the direct route rather than going all the way around the perimeter of the supercontinent?

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    $\begingroup$ Comments are not for extended discussion; this conversation has been moved to chat. $\endgroup$
    – L.Dutch
    Apr 8 at 2:42
  • $\begingroup$ You might want to think a bit more about both the giant interior desert and the around the edge route for your railroads. If you look at Earth continents, you find that the interiors aren't entirely desert, and that the deserts can be in close proximity to oceans. For instance, in North America south of roughly the Columbia/Snake River line, the desert starts at the Sierra/Cascade crest. Yet the first transcontinental railroads went right through the deserts. $\endgroup$
    – jamesqf
    Apr 8 at 15:36
  • $\begingroup$ some interesting for the fact that most rich countries that are at all significantly inland rely heavily on rail freight for the inland areas $\endgroup$
    – OT-64 SKOT
    Jul 19 at 1:14

10 Answers 10

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Firstly, shipping is generally more efficient for bulk cargoes - such as coal, lumber, ore, etc. (assuming you are using a similar technology to power both the ships and trains - i.e. both steam, or both diesel).

Secondly, unless your super-continent is more or less circular the distance across the water may be significantly shorter. For example, take Eurasia and open up the Straits of Gibraltar so the gap between Morocco and Spain is now ~1000km+. It would still be significantly cheaper to send freight via a ship across that 1500 km than to send it by mail all the way around the coasts of Spain, France, Italy, ..., Egypt, Libya, Tunisia, Algeria, Morocco! So if you have a crinkly supercontinent, the sea may often be a shortcut.

Thirdly, unless your super-continent is one political entity there would be the issue of local political unrest, duties and inspection at each border etc. if sent by rail. Shipping can largely evade those difficulties.

Fourthly, dangerous goods are potentially better sent by sea rather than freighting them through all your coastal communities.

I think that is sufficient to make shipping competitive.

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    $\begingroup$ Now I'm wondering if the railroad is viable... Am I correct in thinking that trains are a fair bit faster than boats, even if they cost more per mile? If so, the world-circling railroad might still be feasible as a passenger and express shipping service. $\endgroup$
    – Globin347
    Apr 6 at 2:29
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    $\begingroup$ The rail will still be (mostly) viable. E.G. commuters and/or mail, freight and passengers travelling a few hundred kilometers or less. Similarly for freight and passengers to locations that don't have ports or which are too small to have a regular cargo-ship visit. And also for freight and passengers that need to get somewhere rapidly (assuming the 'crinkly short-cut doesn't exist). Where the costal railway might not be economical is in sparsely populated coast-lines or where the topography makes a railway expensive to build/maintain (in that case use ports/ships to bridge those sections!). $\endgroup$
    – Penguino
    Apr 6 at 2:42
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    $\begingroup$ @Globin347: Whether rail is faster depends on a number of factors; Your tech level, of course: the TGV is rather different than a 19th century steam locomotive. Then there's terrain: trains can go a lot faster across the Great Plains than through the Rocky Mountains, and their routes will be more direct. In mountains, the route will probably have to wind around a lot to keep a sufficiently gentle grade. For an extreme example, see the "Spiral Tunnels" on the Candian Pacific Railway: en.wikipedia.org/wiki/Big_Hill#Spiral_Tunnels $\endgroup$
    – jamesqf
    Apr 6 at 3:47
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    $\begingroup$ @Globin347 Consider the Acela train between DC and Boston, vs the lack of boat options between same. Train is less impacted by weather, so it is more reliable in terms of fixed departure/arrival times. A small train is more comfortable than a small boat. Navigating in/out of a harbor/to a dock can be time consuming, navigating in and out of a train station involves applying the breaks at the correct time. $\endgroup$ Apr 6 at 11:51
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    $\begingroup$ @user3067860 the lack of shipping is largely explained by the Jones act severely limiting ship traffic between US ports, and the considerably slower speed making longer-distance travel unappealing compared to alternatives (planes and busses are comparable substitutes to trains, not ships) while for shorter travel distances ferries are still quite popular all over the world. Trains are more prone to weather issues from snow and ice than boats, and even high winds can still stop train service (Amtrak is hardly known for keeping a perfect schedule). $\endgroup$ Apr 6 at 13:40
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Will the railroad kill ocean shipping? No, it won't

We have a real-world ready-made example showing that ocean shipping and rail shipping can coexist and complement each other.

As it happens, we do have a rather large supercontinent on Earth, called Eurasia. On this supercontinent we have, in the east, the People's Republic, which manufactures just about everything; and we have, in the west, the European Union, which consumes just about everything.

There are at least four rail links between China and the E.U.; two direct through Russia and two through Kazakhstan then Russia:

Guess what? The four main rail links between China and the European Union carry not more than a very few percent of the freight. Basically, they are semi-luxury carriers, used for merchandise which needs to move fast, but it is not precious enough to warrant air cargo.

Why is that?

Because trains have very low capacity. On a train, the containers are arranged in a long file, one container wide and one container tall. A 70-car train might carry 140 TEU; let's say that by ruthless optimization the Khorgos Dry Port can be made to handle 50 such trains per day, for a total of 7,000 TEU. (Not likely, but not something fantastic either.) One container ship (such as one of the Maersk E-Class ships) can carry twice as many containers. And over 250 ships pass through the Malacca Strait each day, every day.

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    $\begingroup$ +1, it's really hard to overstate how incredibly efficient and cheap container shipping is. $\endgroup$
    – eps
    Apr 7 at 20:11
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    $\begingroup$ I have seen trains that had stacked containers, but they were only two high and never for the whole length, so your point stands. $\endgroup$
    – No Name
    Apr 9 at 8:46
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    $\begingroup$ Isn't that more a problem of having a very restrictive loading gauge than one of being rail per se? $\endgroup$
    – Vikki
    Jul 17 at 22:45
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Airplanes can fly over the desert, and they are fast. They'll be viable for passenger transport and express freight, e.g. airmail. But they'll probably be the most expensive mode of travel, but also the fastest.

Ships beat trains in terms of cost/ton. they'll be used for bulk cargo. Coal, ores, lumber, stone, sand, oil, grain and so on.

Trains will be faster than ships, but not as fast as planes. But they can also transport more. They'll be used for cheaper travel, and for commuting. They'll also be used for goods that aren't as bulky as the ones mentioned before, but need faster transport as ships, but are bulky enough to rule airplanes out.

Each mode of transport will have it strengths and weaknesses. What goods exactly are transported how will depend o the details of your world, e.g. the exact technology level, cost of different materials and fuels. And geography. Strong winds disfavor planes, strong currents disfavor ships, rough terrain makes railway construction difficult.

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  • $\begingroup$ +1, but the advantage of trains is not necessarily speed. The average speed of freight trains (~20 MPH) is slightly slower than the cruising speeds of cargo ships (~27 MPH), so it would depend on the shape of the continent if trains would be faster point to point. ie, if your continent is chile shaped, container ships will. As you say, the geography is incredibly important to how everything will work. But overall their top advantage is that you can't container ship things to the middle of a country. $\endgroup$
    – eps
    Apr 7 at 20:23
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    $\begingroup$ @eps Commuter trains and trains for express freight are considerably faster than ships. Also, ships can only be unloaded at a port. Even if only a small strip of land is inhabited, trains might still be desired for distributing goods from the ports, instead of trucks. The point is that all of these modes of transports offer different strengths and weaknesses, and balanced properly by geography, tech level and resource availability, there is little reason why they won't co-exist all in their niche. $\endgroup$
    – Polygnome
    Apr 7 at 20:36
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Ships have a number of advantages here.

One is simply cost per ton to be moved. It's cheaper to move freight by water than by land.

Second, you have much more flexibility. Your trains are limited by the number of tracks. Boats don't really have this problem, or at least not to the degree that trains do. Even if a relatively narrow band of the water is navigable, it will be wide enough for several ships to pass each other in relative ease. Trains are also governed by a schedule. Boats, not quite so much. They can set sail when loading is done, or at least when the tide rolls in at that particular port. Depending on how developed your rail system is, you may have to wait days for a train to stop to pick up your goods. Even then, a ship may be able to carry far more in a single load than a series of rail cars. (Mary's answer mentions both of these points as well, I'm just adding a bit of detail)

Finally, don't overlook how trains and ships can work together. In modern shipping, Intermodal containers rule, and you will quite often see containers loaded on to trains from ships. Since you can pretty much put a train stop anywhere you like, Ships are limited by the availability of safe harbor space. You can send goods around the coast for the bulk of the journey, off load the containers in a marshalling yards to have them loaded on to trains for that last mile to a stop somewhere between harbors or deeper in the interior of the continent.

There is no need for the rail to try to drive shipping out of business. There is a lot more money to be made in working together.

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    $\begingroup$ +1 for the cooperative angle. $\endgroup$ Apr 6 at 18:29
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    $\begingroup$ Thanks. It wasn't a stretch though, as it's how things work in the real world. $\endgroup$
    – Paul TIKI
    Apr 6 at 18:32
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Issues limiting the train's ability to take over:

  • It's easier to move objects over water than over land.
  • Your ships will have more flexibility than your train, not having to worry about schedules of other ships.
  • Much depends on how much the train charges. It may not be able to drive out the ships without operating at a loss, and possibly not even then.
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    $\begingroup$ More flexibility in some ways. Ships are of fixed size, and want to travel full, so they'll contract cargos well in advance. And while a company that owns an entire ship can delay a departure, one which contracts half a cargo bay can't. Trains are much better at sticking a few extra cars on at the last minute. $\endgroup$
    – dspeyer
    Apr 7 at 5:19
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    $\begingroup$ “It's easier to move objects over water than over land.” – That depends on your metric of ease. Due to the much lower density and thus inertia of gases, high speed of movement requires much less energy in them compared to liquids. On the other hand, the construction of ships that float on water requires much less effort than the construction of railways for the same freight volume multiplied by distance travelled. $\endgroup$ Apr 7 at 22:20
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Seas don't require maintenance

Depending on the economics of materials / labor to maintain the rail routes which includes dealing with earthquakes, landslides, plain old accidents like derailments/hitting road vehicles at level-crossings/ road vehicles hitting rail bridges, shipping is much more reliable and cheaper in the long run.

Accidents on a rail line (or even a malfunctioning locomotive) block the entire line. Shipping does not usually have such single point of failures.

In unfavorable political situations, a single nation along the coast can cut off the rail network for the entire world. Rail networks have historically been the critical infrastructure targeted during wars. A sea route that avoids this danger would appeal to every nation situated along the coast.

Current transport ship sizes are mostly limited by the size of the Panama and Suez canals. On a super-continent, this limitation is removed making even larger ships viable.

Shipping also has very low initial cost due to the same reason. Developing a rail network requires cooperation of everyone who controls the land along the route. Starting a shipping route requires two ports and a ship.

Because your super-continent is a circle, any coastal route will always have predictable onshore/offshore winds perpendicular to the shipping route which can be harnessed with good old sails to reduce the fuel costs of shipping.

Given these points, I think shipping would be even more profitable on a supercontinent compared to rail networks for all bulk goods that don't need to be transported quickly.

In fact, as tech progresses, I expect there to be plans to dig canals across the continent linking up whatever interior water bodies it might have given that many such proposals exist right here on earth.

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    $\begingroup$ Seas don't require maintenance but canals do. $\endgroup$
    – Ben Voigt
    Apr 6 at 21:49
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    $\begingroup$ @BenVoigt seas sometimes do require maintenance: en.wikipedia.org/wiki/Icebreaker $\endgroup$ Apr 7 at 14:50
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    $\begingroup$ Seas don't require maintenance, but ports and ships are. $\endgroup$ Apr 7 at 20:24
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    $\begingroup$ Sea routes are hardly immune to conflict or disasters. $\endgroup$
    – papirtiger
    Apr 7 at 22:18
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    $\begingroup$ Also, we have to consider how well the political authorities are able to keep pirates and "railway men" out of each route. Such piracy has closed the Silk Road several times in history. Numerous people tried to shut down the railroads in this country. The Marine Corps has a fight against piracy as part of their heritage. $\endgroup$
    – David R
    Apr 8 at 19:44
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Total freight capacity will still favor ships.

The total freight capacity of a railway is limited by the rail itself. You can only have a certain number of train carriages pass one point on the rail per hour, no matter how you optimize the system. To increase past this point, you need to build another railway line. This requires you to purchase a lot of valuable land, prepare the land, build and place your rails. Then you have to build the trains and carriages needed to use this line.

For seagoing shipping to increase its capacity, you only need to build another ship, and upgrade the docks. The entire distance of the seagoing "track" is provided free of charge.

Your railway will have an essential role for local distribution of the people and goods being moved. Including short trips along the coast. But the further the trips need to go, the more it will favor the ships.

Where the trains are king, is where they are competing with foot/animal/road travel. Trains are almost as fast as vehicles, move the goods much more cheaply.
But they do not compete with ships, for locations where ships are applicable and cargo unit sizes are medium to big.

Even trains crossing directly across the continent are unlikely to be competitive, as the straight-line distance will be some 12000km, which is less than the sea route around of 20000km, but not sufficiently shorter to justify the gargantuan task of building a railway line across 12000 km of uninhabited desert.

Trains will be viable, even essential, once the civilization becomes advanced enough, and rich enough, to actually exploit the interior of the continent for minerals. There is simply no viable way to move the proceeds of an inland mine over long distances, other than by train.

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    $\begingroup$ "almost as fast as vehicles"? railfreight.com/railfreight/2021/01/05/… $\endgroup$ Apr 7 at 13:47
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    $\begingroup$ @BrianDrummond that's 28,5 % of en.wikipedia.org/wiki/ThrustSSC In reality, both trucks and rail freight are much slower. Edit: I only now noticed that you linked an actual rail freight, which is impressive, but I'm skeptical if it will be indeed so fast in practice. $\endgroup$ Apr 7 at 15:47
  • $\begingroup$ @MarkusvonBroady It will; but only on suitable track. Its purpose is to simplify scheduling on HST tracks; mixing fast passenger and slow freight causes big headaches. $\endgroup$ Apr 7 at 16:02
  • $\begingroup$ @BrianDrummond if you want factual but absurdist claims, your train is no competition for russian cargo ships. This one has a cruise speed of 550km/h en.wikipedia.org/wiki/Lun-class_ekranoplan $\endgroup$
    – PcMan
    Apr 7 at 16:28
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Others have pointed out the greater efficiency of ships for bulk cargo.

Worth also pointing out the miracle of the container, which translates practically any cargo more durable than shellfish, into a bulk cargo (and reefer containers can help even there)

In addition to the vastly greater capacity of a ship (20,000 TEU rather than 100 or so) there are no (well OK, very very few) places where the failure of a ship can block the sea, and effectively foul up the entire transportation system for a week.

Rail is much more fragile, especially in coastal areas where storms, floods, landslides, or derailments in tunnels regularly disrupt services.

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  • $\begingroup$ Is land really more fragile to storms than water? No doubt the advantage of ships is that if one decides to hide in near port and wait it out, it doesn't block other ships, though a rail transport artery for whole supercontinent would consist of multiple tracks, so it wouldn't be easily locked. $\endgroup$ Apr 7 at 15:43
  • $\begingroup$ On water, give yourself plenty of searoom - stay away from land in bad weather. Land that is close to water, take Highway 1 in California as an example, is less stable than land in general. Or if you insist on a railway line example, see bbc.co.uk/news/uk-26042990 $\endgroup$ Apr 7 at 16:09
  • $\begingroup$ The rail section in the link is near water. The only reason I can think of why a rail would get destroyed inland is because a tree or rock falls on it, the former can be solved somewhat easily (though it magnifies the problem mentioned in different answers, the cost of building and maintaining tracks). There's also the problem of snow and cold, but with huge amounts of snow it's probably easier to deal with that on rails than break ice on waters 🤔 $\endgroup$ Apr 7 at 17:21
  • $\begingroup$ @MarkusvonBroady maybe I took "around the edge" a bit too literally! Sometimes geography and economics force such a literal interpretation; Devon is notoriously hilly inland, and trains don't much like hills; that's what happened to this line. $\endgroup$ Apr 8 at 11:56
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I can't imagine any possible world where ships and ocean-going vessels are not invented before rail. (Not without some draconian restrictions, like people are made of candyfloss and dissolve on water)

So no matter what, sea freight will be there first. People are used to it, and rail will be the challenging disruptive technology.

The first trains will be just-functional and barely able to haul themselves around, while sailing ships will function as they have for hundreds of years moving holds of freight and passengers around.

Trains would develop over time, but ships will be growing too. Both will exist as steam turbines are invented and improved, then oil, and then (electric/solar/nuclear/other-future-tech).

The only advantage a train has over a ship is that the train can traverse land, where the ship must has a minimum depth of water. If your continent has rivers that are navigable by a ship (think the Thames River up to London) then ships will go up the river.

If someone has resources located inland, that are not accessible by ship/barge via a waterway, then a train will be the "next best thing" and certainly better than a mule train or similar.


Your ring of rail is in the wrong place, out on the coast. If it were a circle through inland cities, with feeder lines running down to the port cities, and inland to mines/farms/canneries/tanneries/etc then the railway will prosper, doing a job that only it can do....

...until the truck comes.

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First, that is such a great question! The answers are preety good already, let me just add that one migh consider Australia as a kind of model for this problem or a "tiny supercontinent". Indeed, you have compeeting Railways, sea cargo and even pipelines over there. However, it seems all transportation methods have their own niche depending on the application area (you cannot transport inland coal via ship). Interestingly enough, goods are mainly transported via roads in Australia, so neither sea- nor rail-transit wins in this (modeled, but realistic) case.

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