Invention Playlist II: Roads

I've definitely had this experience before. And that's not even getting into you know, issues of ticks and other parasites. Oh yeah, there's there's the tick problem, definitely. But like, unless you're somebody with a particular class of outdoor hobbies or lines of work, you would probably be so embarrassed to realize how much of your life you spend on pre selected traversible pathways like the floor of your house or workplace, the sidewalk to the door, the sidewalk down

the road, the road itself. Even when you go out in nature, it's really likely that you probably spend most of your time out there following some kind of forged or trodden pathway. And if you get off the path. Planet Earth almost immediately transforms into this unruly and difficult place with uneven footing and branches and rocks and vegetation blocking your path, sudden drop off, steep inclines. This is Earth, and this is what a large part of the surface

of Planet Earth is like. And much of it is just not made to be quickly and easily traveled over. It's funny, how even if you go out and spend a decent amount of time in nature, you can mostly overlook this fact just by staying on the path. So that's what we wanted to look at today. Something we don't often even think of as a human invention, but in a way certainly is the roads we travel. That's right, it's a it's it's really an essential part of the

world that we have created. Um. But however, if we if we want to understand the human history of roads, and even get into the pre human history of roads, we have to acknowledge the work of our of our non human relatives, of the work of animals, because because

we do have animal paths. To consider the trails left by say, deer in the forest, the buffalo roads across the western plains of North America, animals on the move from one area to another had to push aside vegetation, and in the act of moving they end up trampling down the earth beneath their weight. And we're talking about a lot of weight when we're considering wide ranging megafauna, you know, some of which we still have today, but

we had even more of in prehistoric times. I guess before there were the cattle roads where the orax roads or something. Yeah, and of course when other animals came along in their wake. Uh, these paths were there, and they often represented the swiftest, least least obstructive way to get from one place to another. Yeah, it's certainly interesting to think about animal trails as being a tight of

geomodification or adaptation of the landscape itself to the organism. Now, a lot of the ways that organisms survive are by adapting to the landscape around them. But sometimes they survive by changing the landscape to better suit them, and they don't necessarily do this consciously. Is just their activities bring this about the big examples or things like beaver dams. Beaver dams is just altering the immediate environment or or even looking to mega fauna that such as an elephant

that may push push down trees and other vegetation. Yeah, but of course we can see paths emerging that in some ways play some of the same roles. Yeah, now I do I do want to drive home here though that even though animal trails are are often brought up as being sort of the pre human origin of roads and human pathways and certainly seem to play a role

in them. Uh, there are some who take issue with with giving animal trails too much importance, are arguing that, well, animals don't actually follow consistent paths all the time, so it's not a you know, a definite connection here, but it is one that is pointed out in a lot

of the literature. And speaking of the literature, one of the books that we look to for this episode is a book by the title of Ways of the World, A History of the World's Roads and of the Vehicles that used Them, by Maxwell Gordon lay On, Australian civil engineer, published in nineteen two. In the book, lay says that you know, on this whole issue of animal paths, it really depends on the environment. He says, quote difficult to rain or dense of vegetation in fertile areas would certainly

have required narrow and specific animal ways. So even if yeah, you can say that, uh, you know, animals aren't gonna always follow consistent paths, there are going to be environments where there is like one best way to get from point A to point b. If point a to point B is indeed a path that needs to be navigated by animals. One way to see an analogy here is if you ever look at the the desire paths that form along a college campus or or yard of a

well populated building or something. Do you ever see these at College Robert where there would be like paved pathways, but then branching off in a shortcut between two places, there would be a place where the grass was just beaten down and there was a dusty dirt. Oh yeah, it's generally it's kind of a breakdown in planning because like, clearly you did not plan out the best paved route for for foot traffic. Clearly foot traffic wants to go

this way. But it's kind of beautiful watching those things emerge because nobody planned it that way. Just as you're saying, even the students didn't plan it that way. Just over time, enough people make the same decision about where to go and how to get there, that these natural pathways emerge

until someone throws up a hedge or something. So eventually you have a few species of hominids that come along, and they distinguished themselves in intelligence, and they start forging their own trails, often incorporating animal trails whenever it makes sense as well. So, yeah, if the trail all of the megafauna uh is there, they may use it, but they may also uh beat down their own paths as well. So you know, they would have navigated by doing this,

they would have navigated difficult drain bodies of water. And prior to the coming of Europeans to to the America's the native people's here had they had their own complex system of foot trails by which they could travel the land.

In his book, uh Lay points out the Nachez Trace four dred forty mile or seven hundred kilometer trail that goes from Nachez, Mississippi to Nashville, Tennessee, and it was used by native peoples for centuries and it was said to have, you know, been originally created by buffalo heading north to Salt Licks in the area of what is

now Nashville, Tennessee. Yeah, and this highlights something you might not immediately think about with roads, because roads not only allow you to move more easily by providing a clear path on the surface c C to walk on, they also help you know where you're going. And this could even be the case for animals. Right many animals have

been built navigation capabilities that others don't. As a large bipedal primate, just try to find your way around in the world without a compass or a map or a road, you're probably gonna have kind of a hard time of it. And you can also consider the fact that even if you're not following a familiar road to get somewhere specific, you can follow any road to eventually get somewhere significant. Like people don't usually build roads to nowhere, and that

applies to animals as well. Now in considering lands that have known the influence of humans for far longer than the America's, it has also been theorized that some of the the older winding roads in places like England have their roots in wild animal pathways leading to fords and watering holes. And of course, in the case of many of these ancient trails. Uh, they might remain somewhat fluid for a number of reasons, because you have shifting waterways.

Trees are gonna fall, beavers are going to do their things, storms are gonna uh add chaos as the scenario, So any number of things might occur that that that alter the shape of the path. And of course additional changes would come as humans uh continue to develop their their their their primitive technologies. Right, they require more paths for

their own meager footfalls. The cultivation of crops and animal husband husbandry would have increasingly created a world where certain areas had to remain off limits to animals, particularly to domesticated animals and other zones or you know, roads would need to easily and safely convey these creatures from one place to another. All right, we're gonna take a quick break. When we come back, we're going to continue along the road.

All right, we're back now. Obviously, there is no single inventor of roads, so we can't point to uh dr Rogilus who came up with roads ten thousand years ago. Didn't happen, Sir Walter Rhodes, Uh, No, you know, we've already discussed the foot paths of early humans likely made use of animal paths to some degree. But then what happens again when humans transition out of their mere hunter

gatherer lifestyle. What happens in the wake of the agricultural revolution, resulting in such innovations as domesticated animals and then eventually wheel and sledge constructions for dragging surplus crops, firewood, and

other necessities around. Now, once you introduced the idea of wheeled vehicles, things changed significantly, And it's worth noting as an aside that the strange and fascinating fact that it appears the wheel was not invented for transportation until some time around the fourth millennium b C, like or something,

which at first first exposure to this fact seems shockingly late. Right, Grain agriculture has probably existed since around nine to ten thousand BC, which means that roughly half the time humans have been farming, nobody had wheeled vehicles to move sacks of grain or whatever around. So, of course, maybe we shouldn't be surprised, given that wheels are a deeply unnatural invention, right, So many human inventions have some kind of analogy and nature.

While there are animals that roll their bodies or parts of their bodies in various ways. Maybe the closest is the bacterial flagella, which nobody could have seen the microscope to see. See some of the more wheel like creatures in the Animal Kingdom. But even that's not really a wheel. There's just nothing in nature that operates on a wheel and axle, and we should definitely revisit the invention of the wheel future. That's a no brainer. We have to

come back to that. But so, yeah, think about this, just thousands of years of agriculture and road in some way road based transport, at least some primitive forms of roads without wheeled vehicles on them. Yeah. Now, on the subject of domesticated herd, you might well require a dependable road to connect winter and summer grazing lands, and indeed we see examples of this in the Cannadas realists in Spain. These are drovers roads covering hundred and twenty five thousand kilometers.

Another example of the the Welsh Roads of England that linked scott At Scotland and Wales to London markets. Again just moving domesticated animals from one place to another. Yeah, roads are necessary for the development of trade and in many ways you could say for the development of culture. I mean, almost everything that we think of in culture comes ultimately from the connections of people's to each other, you know, the meeting of different minds across distance, and

that's all enabled by roads in trade. Yeah. And even though a lot of these roads change over time, obviously, and and you don't find a lot of paths that remain in use for just extended periods of time, but you do see these wonderful examples of some of these pathways, particularly in North America and Britain, where just they have centuries of wear and tear and they've essentially become a little trenches just from all the of the foot traffic.

And that is is pretty amazing. Yeah. Though the Roman roads were dug out to be in with I believe or at least some of them were, right, like they would dig down a trench in a way to become the road. Oh yeah, And that's where we're getting in

really into a serious construction of roads. And ultimately, that's what we need to talk about at this point, is when when you start constructing a road, it's not merely well, we sure did move those goats from from here to there enough times that there's the best way to do that. You know what, what happens when we get into the idea of of planning a road, manufacturing and reinforcing it,

caring and maintaining it. When we started asking that question, well, Lay says that quote, uh, the creation of major lowland ways required a degree of engineering skill and organization that began to develop around four thousand BC. It points out that the oldest British quote planned and engineered pathways date back to Glastonbury, UK thirty three thousand b C. And uh, good local roads ultimately helped the Britains defeat the Roman

legions in fifty five b C. And now. Of course, on the other hand, extensive, high quality roads are a major factor in the military success of the Roman Republic and then the Roman Empire right or really any any particular empire. I think back to episodes of of stuff double your mind that you and I did on the Inca and the important of the the Inca road system, which also incorporated uh, tremendously impressive rope bridges, and how

that contributed to the success of the Inca. Yeah, great part of the power of the Inca Empire lay in its transportation and communication infrastructure. Yeah, and if you want to quickly convey your troops from one point in an empire or kingdom to another, especially across difficult terrain, in order to defend or expand a kingdom, um, you're going

to need good roads. And indeed we see this reflected even in recent history, say the United States Interstate system in the early twentieth century, it was considered necessary for national defense. Yeah, definitely, and their more stable reasons that roads are necessary for for military purposes. I mean, one, of course, is to get your armies to places. That's

the obvious one. But the other one is the thing that a lot of times people you know, when they're when you're playing your historical military games, like that, would Julius Caesar's army to feed the Mongols or something like that? You know, you're you're doing all that stuff. People like to think about commanders and weapons and fighting styles and all that, but they don't think enough about the real thing that makes or breaks a war campaign, which is

supply lines, the ultimate gremlin of military history. The army marches on its belly, right, Yeah, and undersupplied army can't fight at full strength, and so the supply lines, how you get food and other major supplies to your troops, how you bring reinforcements to the front. I guess that all falls under the military category of logistics. But that's a huge part of the success of a military campaign. Now it's easy for us to get caught up in

the you know, these sort of country roads. We've been talking a lot about a lot of cross country paths and roads. But as as Life points out in his book, Um, you know, going back to two ancient times, uh, you see roads as a necessity of city planning. As cities become a thing for for human beings, it becomes necessary to think about how people were moving around in them, what sort of of of streets or roads are present. And you see this in the work of the ancient

Egyptians and various Middle and Near Eastern civilizations. Uh. The use of roads and sinning city plannings was discussed in the writings of, for instance, Greek city planner Hippodamus in Uh in later reference in the works of Aristotle and others, and sometimes city plans were based more on engineering, and other times there was a there was some element of mysticism, as well, which seems seems like it would be highly susceptible to mysticism the construction of roads, because it is

this kind of complex like system of on language that you're laying out across the world. Roads appear in all kinds of myths and legends and religiously significance to worries. The Road to Damascus, the Road to m s the row, little red riding hood on the road to her grandmother's house. Yeah.

How many um horror stories throughout history are essentially stories about what happens when you go off of the path or the road, right right, Yeah, Mirkwood in the Hobbit, Yeah, if they stick to the road, gentlemen, and you're not gonna encounter problems, don't go chasing elf lights into the dark. Now.

Of course, we'd be remiss if we did mention one of the great roads, the Silk Road, an example of roads running into other roads to become more or less a single pathway dating back to roughly three kind of connecting various caravan routes across Eurasia. One of the all time grades. D Yeah, top top top five, top three. To be sure, all right, we're gonna take a quick break, but we will be right back. All right, We're back, okay. Now.

One thing that certainly changes about road it's over time is that the original roads were just beaten down areas of earth, right and where the there where the cattle or the large bovids or whatever would push through. They trample down the ground and make it flat, and they push the vegetation aside, so there'd be a clear pathway going somewhere. But over time roads took on a more technological character. People were looking for better ways to make

more reliable roads. Because you got a road like that that's maybe just some trampled down cleared earth. Maybe let's say you have some heavy rains. What you tend to find is that the road like that gets a little bit washed out in the roads. Yeah, I mean in in in our own neighborhoods here in Atlanta, we we have at least a few examples of this where we have an unofficial pathway and then what happens when it

becomes a muddy wreck. And then you see some very amateur essentially road building where people are like, well I'll just dump a bunch of rocks in here, or I have some tire garbage that will really help things out. Yes, I will fix the path with a whole bunch of cans or something. Yeah. And it essentially this is kind of what we see in some of the the early corduroy roads or log roads that are that are created to deal with muddy terrain. Oh they're better than cans,

I guess. But but essentially we're talking about placing logs perpendicular to the direction of the road. And examples of this sort sort of road date back at least four thousand years. Uh. There's the so called post track in Somerset levels, England, for instance. Uh. And it makes sense, right, Like, what what do you do if your your vehicle is stuck in the mud, right, just grinding, grinding the mud

until you're buried. You get you get some sticks or law, you know whatever, pieces of wood and you put them under the tire. You want something to pull up on some traction. Yeah, you want to put something under the tire that will stay where it is when you're driving. Yeah. So that is essentially what say, you know the post track is lay mentions another one. He says the sweet track uses longitudinal log to support oblique crossed pegs which form a v uh every meter or so planks between

these create a walking path. And this is the Sweet Path from near Glastonbury, which dates back to uh. Three thousand BC. Now, Robert, when did people first come up with the idea of the old the old popper the gravel road? Ah, you know, I was. I was thinking about this, and I was reading around in lays book and looking at a couple other sources on this, and um, yeah, it's one of these things that that feels like it should be pretty archaic, because again we come back to

that idea, what do you do when the path gets muddy? Well, one solution is get some rocks and throw them on there, right, And that that clearly seems to have been something that would have been utilized by by our our ancient ancestors. But but when you start really thinking about gravel roads, it gets pretty interesting. We can really take the technology

and the labor involved. For granted. For example, was recently in Costa Rica and we went up to Monteverde in the cloud forests and to get to Mount a Verde, Uh, you have to take this this winding road, and more and more of it is paved now, but there's still a stretch that is gravel and and these are these are good gravel roads. I don't want to cast any unnecessary shade on the roads of Costa Rica because uh uh you know, we never felt in danger or anything.

You know, these are these are nice gravel roads. Uh, I mean, hey, I've been on some scary gravel roads in Georgia. Oh yeah, yeah, I mean, and if I'm being honest, like gravel roads in general like tend to wig me out, but probably unnecessarily so. But yeah, I think think about about what essentially a gravel road is.

Instead of lining the road with wood, you cover it with dirter rocks or gravel, uh, taken from well, in today's cases, some sort of quarried area, right, but more likely in older examples you'll be talking about rocks from a creek bed. The problem, of course, is that gravel can be washed away and then you have you have this huge task of hauling it all the gravel back up and then distributing it where it needs to go. And this can be quite intensive. I mean, just look

at modern cases. If you see any kind of maintenance going on, or you know, if you happen to get to see the creation of a gravel road, you're going to see the hauling and distribution via you know, massive

pieces of equipment, dump trucks and what have you. Uh. And perhaps this is a major reason you tend to see more widespread use of gravel roads in say, early twentieth century US and twentieth century developing areas and nations as well, because it simply becomes cheaper to transport and dump all the necessary gravel, which is of course again now mind and transported on dependable roadways rather than just laboriously transported from stream beds to uh, you know, roadways

that might be questionable in their own right. The age of the dump truck made it possible. Yeah, so think about that the next time you're on a gravel road. Realized that this is perhaps more of a modern conveyance than you're giving giving a credit for. Now. Of course, when we talk about like the best, the most modern examples of a road, you're gonna think of paved roads, right, These are the gold standard. I thought you were gonna

say a rainbow road. No, but I guess a rainbow road would probably be paved as well, because the gravel rainbow road would just become distorted from all the traffic is that would be really difficult to maintain. And yet here's the thing. As modern as these fields, even though this feels like the height of modernity, these actually go back quite a long ways in human history as well.

So you have stone paved roads that date back to, for instance, the Middle Eastern city of er Uh circa UH four thousand b C. You have brick paved roads in India that date back to three thousand BC, and we also see them in Malta from around two thousand to b C. Basically, as humans developed and improved the ability to cut stones and mix mortar, they crafted not only walls but roads, because ultimately, what is what is a road but a kind of wall that is laid

on the ground. Right, the technology is not all that different, okay, But then there was also, i mean, the development of um what would you call it, the supporting infrastructure around the road. If you look at, say some of the stone paved Roman roads, you'll see that they not only had this paved surface, but they had protective elements like they had like retaining walls or ditches, you know, to get the right kind of drainage or protection from the

road against the elements. Oh yeah, drainage. Drainage is key and and waterproofing. And this leads us to the bitumen roads, which are pretty pretty interesting page from the history of road technology. First, just a reminder, and what bitchuman is? It's the word I can never remember how to pronounce the American way. I think we say it the British way, which is bitumen. Yeah, it's it's it's a mouthful, but it's It's also the arguably the world's first petroleum product.

It's a sticky, black viscus substance and uh. And when it's combined with mixed with sand and stone, you get essentially asphalt. But it was highly prized in the ancient world and for the longest it was primarily a Mesopotamian monopoly, and it's alid use in various endeavors things everything from art and cosmetics to just cocking your boat. Uh. Didn't we talk about it on an episode of Stuff to Fill Your Mind? Is a potential constituent of Greek fire. We did, yes, And it also came up in an

older episode on mummies. Actually the word the word mummy is linked to the word bitumen. Uh. And then of course, physicians in the in the region eventually used it to treat a number of ailments, but by three thousand b c e. It was used in mortar, among other things, and by it was used in waterproofing, and it was

later used in roads along with burnt bricks. And around six fifteen BC, King Nebuchadnezzar and his father Nabopolassar mentioned it's mentioned its use in streets paved for the procession of the great god Marduke. Oh, nothing less for the

feet of Marduk. Yeah. But then this brings us back to the Roman roads, which we've already been touching on, because though the Roman roads are generally considered the peak of row making in the ancient world, the one shouldn't dismiss the roadmaking prowess of say the Persians and the Chinese before them. But still this was an empire like famous for their roads. We have the saying all roads lead to Rome for a reason now is lay points out.

Rome was, of course an empire, and empires have a way of taking certain things, either culturally or technologically, from from others, either those who have come before or those who are brought into the empire. Right, so they made use of Greek lime cement and masonry. Uh, it trust

can cement, uh, Carthaginian pavement and Egyptian surveying. Uh. They famously utilized lime based concrete as early as five hundred nine b C. And what's crazy is that after the Roman Empire collapsed around four hundred C, concrete construction basically disappeared from Europe and it didn't pop up again until

roughly seventeen fifty four. And that's when a gentleman by the name of William Smeaton, founder of civil engineering in England, developed a mortar of limestone and clay that hardened underwater. All right, so we've we've kind of breezed through the history of roads here. Again. Leigh has a whole book on this and it's a great read. So I recommend anyone check that out if you want to deep or dive.

But this brings us to the legacy of roads. It's really difficult to think about our world without roads in them because roads just criss cross everything they can. They can truly be seen from space. Even a few Roman roads and especially some desert highways, really stand out against the surrounding environment. Yeah. Well, I mean It's interesting how often um roads and pathways have remained the same for

so long, or remained close to the same. It's one of the bridges between the technological civil infrastructure of the ancient world in the modern world. Uh. The way, in Europe you still find so many of the Roman roads basically in use. And of course one of the things about roads remaining in use is that you here have to build new roads over the old roads, or you

have to just maintain the roads. You have essentially continuously rebuilding them piece by piece, and kind of a ship of theseus uh manner, I suppose, uh And and along these lines, um Scott Benjamin who does some some research for this show. He u. He pointed us in the direction of a Midwest blog post titled how much does it cost to build a mile of road? With some

interesting stats in it. Yeah, this is something I've never really considered before because we see road maintenance going on all the time, and generally our main reaction is, oh, this is annoying, this is slowing me down. So just consider these stats. Uh, these these are these are these

regard building the road, forging a new road. Okay, to build a new two lane undivided road in a rural area cost between two and three million dollars per mile, and in urban areas that's going to go up to three and five million, because you're gonna have to deal with with because of all the stuff you're gonna have to go around, all the infrastructure you're gonna have to deal with, et cetera four lane highway, you're talking about between four and six million in rural areas and in

suburban areas between eight and ten million again per mile. The US currently has somewhere in the neighborhood of sixty one million lane miles, and to to mill and resurface a four lane road it costs an average of one point twenty five million dollars per mile. And if you're looking to do a four to six lane expansion on top of that four million dollars. Sounds like we need to get into the road business. Well, in a way, it's a great, great business to be in, I guess

because the roads. The roads are everywhere. The roads are even the best roads are continually falling apart because they're weathered by all of these forces we've discussed, plus the intense traffic traveling atop it we're going to keep needing them, Yeah, and we also keep coming up with new twists on the concept. Now, one of my favorite concepts of regarding the future of roads is UH is certainly a lofty one,

but one that is attractive in many ways. UH. And it is the idea of an underground automated highway or you a h like a subway. Essentially, it's like, the idea is, we've we've kind of corrupted the world. We've divided up this the natural world with all of these roads, and anytime animals try and cross it, they die, and

it's breaking up for us, et cetera. But what if we were able to put all of those roads underground or in some cases, you know, build some sort of green structure over it, and the animals could crawl over that, the vegetation could grow a top of it, and they would have all they would be all of these uh environmental benefits as well. What if we had this kind of world and then on top of that that, you know,

the cars are going to drive themselves as well. So imagine like those wildlife bridges, but it's not a bridge, it covers the entire road exactly. Yeah. Just what if we just had nothing but wildlife bridges, and it just kind of concept. And there have been some lovely, uh you know, illustrations depicting what this kind of world would look like and and that they do kind of line up with a lot of these, you know, very ambitious and optimistic visions for what the future of say, you know,

certainly like Middle America I guess would look like. I mean, you could also certainly put the roads underneath the cities, like everything becomes the subway in an urban environment. Um, I don't know. I haven't looked recently to see what even the most optimistic time frame is for this sort of thing, but it's it's a lovely technological dream if nothing else. Oh yeah, I mean to imagine cities where

all of the surface spaces for pedestrians or is green space. Yeah, like, it's not even for pedestrian humans, it's for pedestrian deer and and mega fun let's bring them back to and released crocodiles. No, seriously, I do like that, but until we get to that point, we are stuck with the roads we have, which are pretty impressive technological feats. Yeah. All right, So that's it for this week's episode. Of Invention.

If you want to learn more about the show and check out other episodes, head on over to our website invention pod dot m. Big thanks to Scott Benjamin for research assistance with this episode, thanks to our audio producer

Torii Harrison. If you would like to get in touch with us directly with feedback on this episode or any other, to suggest a topic for the future, or just to say hi, let us know how you found out about the show where you listen from all that kind of stuff, you can email us at contact at invention pod dot com.