conworlding, planetary science and trains
Posted: Mon Jun 19, 2023 3:40 pm
these last couple years or so I've become interested in the engineering and history of rail transport: this has to do in part with local political and historical considerations, but also with the fact that they're just cool. This has brought me to the reflection that, in conworlding, we rarely pay attention to supply chains and the technologies utilized for production and moving around of goods and raw materials. Turns out rail transport, in the most lato sensu of having wagons that move around on some sort of rail <as opposed to moving around on a flat surface>, is just fantastically old technology, five thousand years ago or something like that. Of course, in principle, a conworld might as well never have developped it: the ancient civilizations of the american continent, while well aware of the concept of the wheel, don't seem to have found much use for the wagon: this is possibly to do with the local geography, possibly with their not having domesticated burly beasts of burden. Nevertheless they managed to achieve all of the classical "milestones" of civilization, such as writing and monumental architecture and all the rest of it, if that's the sort of thing one were to care about. Still, wagons are useful things to move stuff around on. this is intuitive enough.
Slightly less intuitive, though, is rails: ¿what's the deal with rails? like... I don't know, call me american or product of the de-trainification of my native country, but growing up I was always confused about trains: sure, they looked nice, but why did they run on *rails*? isn't it impractical that you can't run on roads? isn't it annoying to not be able to steer? who wants to roll over steel, anyway? don't you get problems with very low traction? You see, it's a natural, logical progression.
You need to transport 100 kilos of fruit: it's going to rot here, but back home mom can make it all into jam and, thus, make it stay edible for a long time. say you have a wagon all made out of wood<or whatever other similarly useful material, like seashells or rocks or horn or whatever you want that's hard and plentiful enough to be fit for purpose>: you pull it across a fairly flat field an things are good. it's much easier to pull the fruit on the wagon that to chuck them on your shoulder: for one thing, you *can't* carry 100 kilos on your back, but the wagon can. It's work, but it's doable. But the next day it rains, and the wagon is no longer working: or, rather, it does work, but it sinks into the mud so much that all the effort you're putting into pulling the thing is being wasted on scramblingh the mud around instead of, you know, getting mum her fruits. this gives you the basic intuition that informs rail transport: the concept of rolling resistence.
Seee in principle, if you had a very rigid wheel and a very rigid road, a very smooth and lubricated bearing on which your wagon rests, and so on, it would be very easy to move things around. Now that the road has become soft and plastic moving the wagon is night impossible. this principle is useful to have in mind: the stiffer the whole thing is, the easier pulling the wagon is going to be: this of course, as you found out with the mud, includes the rolling surface but it also includes the wheels themselves: just like the road deforms under the weights of the wheels, the wheels also deform under the weigth of whatever they bear, sandwitched as they are between your wagon and the ground, and that deformation also requires energy. You can make things better for yourself by stiffening up your wheels: making them, you know, out of something stiff, like wood, and put spokes on it so that it'll bend as little as possible. and maybe even put a nice layer of something even harder, like iron, around the wheel to protect it from stuff and make the wheel last longer. stiff wheels are just ace! they make life so much easier, but still, it's no good for your wheels to be stiff if your roads are all soggy and wet and soft.
The natural solution to this problem is to make a road of as hard and smooth a material as you can. you need to find a material that is at once very smooth and very hard, that doesn't deform under pressure and that can bear the punishment of, well, people and horses and wagons walking all over it.
One choice is rammed earth: we call this a dirt road and, honestly, it's not amazing but it works, you know, fine: it's much more pleasant to walk on it than to make your way through underbrush and thorny berry bushes and the like. Still, it gets muddy with rain and if people don't walk over it, keeping the earth rammed, then things will grow on it and it'll eventually become, well, a part of the forest or field or shrubland or whatever natural environment you happen to live in. But what if we cook the earth? well, yes! this works, it's called bricks. bricks are somewhat brittle and they break, but brick roads do, in fact, exist. how about stone? yes! stone does work and stone paved roads are, in fact, the gold standard of road paving quality throghout history: the romans, the tawantinsuyu, chinese, everyone who was a big an powerful empire made stone paved roads. paved roads are just ace.
Okay so the emperor built a very hard, very smooth stone road and you're about to move your cart over it to the next village, where mum lives. Well you see there's a problem with hard, smooth roads, and that problem is grip: you never had to worry, on your dirt paths, about your wagon slipping around and going where you didn't want it to go, did you? you actually had to work hard to make it go anywhere: but now, as the rolling resistance is lower and lower your wagon just slips everywhere. especially when it rains! this is horrible! oh, how will we get mum her fruits?
If your supply chain is not that important or high-volume, that is to say, if it's only from time to time you need to get a little bit of fruit to mum, then you leave well enough alone: the road is not perfectly smooth, it's just mostly smooth: and that's better, honestly, cause then the wheels have enough friction and resistence and so on that your wagon doesn't fly away from you. but what if it's a veeery high volume, very important road where everyday, all day, people need to be moving goods? for example the way from a port to a city or something?
turns out the mere act of using a road a lot makes it a better road for wagons, because the wheels wear it down and wear it down until there are grooves. granted, for this to happen a few things have to be true: the wagons need to have the same separation between the axles, and also there has to be a definite optimal path along it: but where a groove starts to form people immediately realize that life's a lot easier for them if they just put their wheels into the groove: not only is the surface inside the groove smoother than the rest of the road, they also don't need to worry about steering the wagon: the groove takes care of that. grooves are just ace.
So how can we leverage this principle in order to move freight around cheaply and easily? we don't want to have to build an entire stone paved road, that's too expensive. what if we need to move stuff over yonder, but we don't want to have to wait for the emperor to build a stone road, or for wagons to carve grooves? Okay, so this far we have concave grooves and convex wheels, right? it's the edges of the grooves that keep our wagons on the path we want.
These sorts of paths, called wagonways, have the immense advantage of being as heavy as a person or horse can pull. you simply cannot pull this off on a road wagon, because it needs to be able to stop, go, turn around, it needs some degree of agility: not rail vehicles, though: as long as they can be coerced into stopping at all they can be driven around, moving stuff. also they're predictable, so you're never wondering if it'll hit you or not: you're either in its groove, in which case it will, or you're not on its grooven, in which case you're safe. But in order to have a these excellent grooveways, we need to have a lot of paved road and then have people carve the grooves over millenia and... what if we only wanted the grooves though?
build grooves, of course. take a log and carve a grooven onto it as thick as your wheels. boom, you have a lot of the advanges of the groove in a stone path without the stone path. a much cheaper wagonway, with most of the advantages of a wagonway! but okay, okay, hear me out: what if we turn it around: what if we make convex grooves and concave wheels? okay, you can't have a convex groove, but lt's call it something else: instead of grooves into a path, we make, out of some hard and cheap material like wood, just a big thing for wheels to roll on top of, a bit higher than the ground and, instead of having a veeeery long groove, you build an anti-groove onto your wheel. the wheel keeps itself on track as it slides and rolls over these rails because of this anti-groove. a portable groove which keeps your wheel on track. how do we call this anti-groove and convex wheel arrangement? maybe the antigroove we call a rail, or an edge rail, and the self-guiding part of the wheel we call a flange.
what if you want something even better? you could make the path out of metal, now, couldn't you? like... it's too expensive to build an entire path out of metal, but if you just make two rails an lay the wheels on top of the rails, then it might not be as expensive... and if we have an industrial revolution and bessemer steel and blablabla, then even better! in reality, this all evolved rather messily: wooden rail systems were diverse, and sometimes they'd have grooved rails and flangeless wheels, sometimes rails and flanged wheels, maybe two flanges per wheel, maybe one flange per wheel, maybe only the left wheels have flanges and the right ones are free, to absorb any imperfections in the track layout. maybe the wheel doesn't have a flange but it's circularly concave so it can better roll onto the cheaper sort of rail there is: a barely de-branched log. Maybe instead of a flange your left wheel is higher on one edge than the other, so it wants to go to the right, and your right wheel is reversely uneven so it wants to go to the left, and then you don't have to worry about expensive flanges... maybe you put a flange just in case, though, for extra safety: even after the introduction of metal rails and wheels people would still put the flange on the track, sometimes, instead of on the wheel: instead of building complete grooves, people would sometimes just build an iron plate with one flange, and then for the other rail, another plate with just one flange on the other side: this way, you spend less material of flanges and you still don't derail. And from here we're in recognizeable territory: if you have an engine that can produce force you can put it on one of the wagons, and let it pull other wagons, which is amazing because now the whole thing moves without having to pull it. and then, well, you have a train.
____
on future posts, ramblings about how planetary parameters such as gravity, atmospheric density, and the availability of materials might affect the viability and development of rail transport: can you have trains without fossil fuels? how thick does the air need to be for you to have sail trains? how much earlier -or later- in the technological development of a society could you have trains? that kind of thing.
Slightly less intuitive, though, is rails: ¿what's the deal with rails? like... I don't know, call me american or product of the de-trainification of my native country, but growing up I was always confused about trains: sure, they looked nice, but why did they run on *rails*? isn't it impractical that you can't run on roads? isn't it annoying to not be able to steer? who wants to roll over steel, anyway? don't you get problems with very low traction? You see, it's a natural, logical progression.
You need to transport 100 kilos of fruit: it's going to rot here, but back home mom can make it all into jam and, thus, make it stay edible for a long time. say you have a wagon all made out of wood<or whatever other similarly useful material, like seashells or rocks or horn or whatever you want that's hard and plentiful enough to be fit for purpose>: you pull it across a fairly flat field an things are good. it's much easier to pull the fruit on the wagon that to chuck them on your shoulder: for one thing, you *can't* carry 100 kilos on your back, but the wagon can. It's work, but it's doable. But the next day it rains, and the wagon is no longer working: or, rather, it does work, but it sinks into the mud so much that all the effort you're putting into pulling the thing is being wasted on scramblingh the mud around instead of, you know, getting mum her fruits. this gives you the basic intuition that informs rail transport: the concept of rolling resistence.
Seee in principle, if you had a very rigid wheel and a very rigid road, a very smooth and lubricated bearing on which your wagon rests, and so on, it would be very easy to move things around. Now that the road has become soft and plastic moving the wagon is night impossible. this principle is useful to have in mind: the stiffer the whole thing is, the easier pulling the wagon is going to be: this of course, as you found out with the mud, includes the rolling surface but it also includes the wheels themselves: just like the road deforms under the weights of the wheels, the wheels also deform under the weigth of whatever they bear, sandwitched as they are between your wagon and the ground, and that deformation also requires energy. You can make things better for yourself by stiffening up your wheels: making them, you know, out of something stiff, like wood, and put spokes on it so that it'll bend as little as possible. and maybe even put a nice layer of something even harder, like iron, around the wheel to protect it from stuff and make the wheel last longer. stiff wheels are just ace! they make life so much easier, but still, it's no good for your wheels to be stiff if your roads are all soggy and wet and soft.
The natural solution to this problem is to make a road of as hard and smooth a material as you can. you need to find a material that is at once very smooth and very hard, that doesn't deform under pressure and that can bear the punishment of, well, people and horses and wagons walking all over it.
One choice is rammed earth: we call this a dirt road and, honestly, it's not amazing but it works, you know, fine: it's much more pleasant to walk on it than to make your way through underbrush and thorny berry bushes and the like. Still, it gets muddy with rain and if people don't walk over it, keeping the earth rammed, then things will grow on it and it'll eventually become, well, a part of the forest or field or shrubland or whatever natural environment you happen to live in. But what if we cook the earth? well, yes! this works, it's called bricks. bricks are somewhat brittle and they break, but brick roads do, in fact, exist. how about stone? yes! stone does work and stone paved roads are, in fact, the gold standard of road paving quality throghout history: the romans, the tawantinsuyu, chinese, everyone who was a big an powerful empire made stone paved roads. paved roads are just ace.
Okay so the emperor built a very hard, very smooth stone road and you're about to move your cart over it to the next village, where mum lives. Well you see there's a problem with hard, smooth roads, and that problem is grip: you never had to worry, on your dirt paths, about your wagon slipping around and going where you didn't want it to go, did you? you actually had to work hard to make it go anywhere: but now, as the rolling resistance is lower and lower your wagon just slips everywhere. especially when it rains! this is horrible! oh, how will we get mum her fruits?
If your supply chain is not that important or high-volume, that is to say, if it's only from time to time you need to get a little bit of fruit to mum, then you leave well enough alone: the road is not perfectly smooth, it's just mostly smooth: and that's better, honestly, cause then the wheels have enough friction and resistence and so on that your wagon doesn't fly away from you. but what if it's a veeery high volume, very important road where everyday, all day, people need to be moving goods? for example the way from a port to a city or something?
turns out the mere act of using a road a lot makes it a better road for wagons, because the wheels wear it down and wear it down until there are grooves. granted, for this to happen a few things have to be true: the wagons need to have the same separation between the axles, and also there has to be a definite optimal path along it: but where a groove starts to form people immediately realize that life's a lot easier for them if they just put their wheels into the groove: not only is the surface inside the groove smoother than the rest of the road, they also don't need to worry about steering the wagon: the groove takes care of that. grooves are just ace.
So how can we leverage this principle in order to move freight around cheaply and easily? we don't want to have to build an entire stone paved road, that's too expensive. what if we need to move stuff over yonder, but we don't want to have to wait for the emperor to build a stone road, or for wagons to carve grooves? Okay, so this far we have concave grooves and convex wheels, right? it's the edges of the grooves that keep our wagons on the path we want.
These sorts of paths, called wagonways, have the immense advantage of being as heavy as a person or horse can pull. you simply cannot pull this off on a road wagon, because it needs to be able to stop, go, turn around, it needs some degree of agility: not rail vehicles, though: as long as they can be coerced into stopping at all they can be driven around, moving stuff. also they're predictable, so you're never wondering if it'll hit you or not: you're either in its groove, in which case it will, or you're not on its grooven, in which case you're safe. But in order to have a these excellent grooveways, we need to have a lot of paved road and then have people carve the grooves over millenia and... what if we only wanted the grooves though?
build grooves, of course. take a log and carve a grooven onto it as thick as your wheels. boom, you have a lot of the advanges of the groove in a stone path without the stone path. a much cheaper wagonway, with most of the advantages of a wagonway! but okay, okay, hear me out: what if we turn it around: what if we make convex grooves and concave wheels? okay, you can't have a convex groove, but lt's call it something else: instead of grooves into a path, we make, out of some hard and cheap material like wood, just a big thing for wheels to roll on top of, a bit higher than the ground and, instead of having a veeeery long groove, you build an anti-groove onto your wheel. the wheel keeps itself on track as it slides and rolls over these rails because of this anti-groove. a portable groove which keeps your wheel on track. how do we call this anti-groove and convex wheel arrangement? maybe the antigroove we call a rail, or an edge rail, and the self-guiding part of the wheel we call a flange.
what if you want something even better? you could make the path out of metal, now, couldn't you? like... it's too expensive to build an entire path out of metal, but if you just make two rails an lay the wheels on top of the rails, then it might not be as expensive... and if we have an industrial revolution and bessemer steel and blablabla, then even better! in reality, this all evolved rather messily: wooden rail systems were diverse, and sometimes they'd have grooved rails and flangeless wheels, sometimes rails and flanged wheels, maybe two flanges per wheel, maybe one flange per wheel, maybe only the left wheels have flanges and the right ones are free, to absorb any imperfections in the track layout. maybe the wheel doesn't have a flange but it's circularly concave so it can better roll onto the cheaper sort of rail there is: a barely de-branched log. Maybe instead of a flange your left wheel is higher on one edge than the other, so it wants to go to the right, and your right wheel is reversely uneven so it wants to go to the left, and then you don't have to worry about expensive flanges... maybe you put a flange just in case, though, for extra safety: even after the introduction of metal rails and wheels people would still put the flange on the track, sometimes, instead of on the wheel: instead of building complete grooves, people would sometimes just build an iron plate with one flange, and then for the other rail, another plate with just one flange on the other side: this way, you spend less material of flanges and you still don't derail. And from here we're in recognizeable territory: if you have an engine that can produce force you can put it on one of the wagons, and let it pull other wagons, which is amazing because now the whole thing moves without having to pull it. and then, well, you have a train.
____
on future posts, ramblings about how planetary parameters such as gravity, atmospheric density, and the availability of materials might affect the viability and development of rail transport: can you have trains without fossil fuels? how thick does the air need to be for you to have sail trains? how much earlier -or later- in the technological development of a society could you have trains? that kind of thing.