Plant-based Roads

[Varyon]

Thinking about my Harpyias setting a bit recently, I find myself returning to the issue of roads. One aspect of Harpyias is that all of the colonized planets are relatively young, such that those that can support life have only recently (from a geological perspective) begun to harbor it. In addition to this meaning all life on such planets is rather simplistic (to the extent that Earth life supplants it pretty much immediately), it also means there are no fossil fuels or the like to draw on. For energy, this is essentially a non-issue - energy tends to be generated planet-side using superscience power plants that essentially steal energy from hyperspace (in space, where heat engines don't work quite as well due to lack of a convenient atmosphere to dump into, solar tends to be the primary source).

Of course, lack of fossils also means a general lack of lime, which means a lack of cement (to say nothing of asphalt), which means roads aren't so easy to make. Additionally, I want a lot of areas to have a bit of a "frontier" feel to them, meaning established roads are unlikely, but want wheeled electric vehicles to be common and useful.

An idea I had, and would like to run by the forum, is a kind of genetically engineered plant. It is essentially a vine with a shallow root system, and it is designed to rapidly grow in a manner where each individual vine is tightly wrapped and packed in with others, forming a hardy surface that can stand up to being driven over by even rather heavy vehicles (electric equivalents to modern semi tractor-trailers, for example), yet is flat enough to give a smooth ride. It wouldn't be quite as resilient as, say, modern asphalt, but would make up for that in the fact that it would be self-repairing. The plant would be controllable by chemical means - trace amounts of a specific chemical (something rarely - or never - encountered in nature, cheap to manufacture, and largely-harmless) essentially serves as a "don't grow here" signal to it, while larger concentrations trigger it to destroy itself. Upon said signal, the vines would first become weak and brittle, then slowly break themselves down into a sort of slurry of biofuel.

Essentially, upon colonizing a new world, humans would spread the seeds for these vines over the surface. The vines would rapidly cover the exposed continents (at least, in areas where the vines can grow, although I intend them to be hardy enough that pretty much if any plant can grow somewhere, the vines can). When humans settle into a new area, they spray the control chemical over areas where they need to get rid of the plant (for growing crops, building structures, etc), then either wait for it to become weak and pull it up or wait a bit longer for it to turn into a biofuel slurry and simply burn it. Keeping the soil with trace amounts of the control chemical prevents it from regrowing, and now you end up with a world that's covered in oxygen-producing greenery that also serves as roadway (and even smooths out drops and rises). The biofuel slurry wouldn't be very useful as an energy source - the superscience power plants are more efficient and less polluting than internal combustion engines, and most things are powered by superscience powercells that have a higher energy density than the biofuel - but may be able to be processed into plastics, fertilizers, etc (covering some of the other issues the lack of fossil fuels would cause).

Does this sound feasible? Is there a simpler solution? Are there problems I'm not foreseeing here? The society in question is very roughly around TL 10 (it's really more TL 8-9 with a healthy heaping helping of superscience), if that helps.

[ravenfish]

The simplest solution for roads-without-asphalt is of course dirt roads- during periods when there isn't rain to turn them to mud, they can function remarkably well, considering. A layer of gravel can allow them to continue functioning even in quite rainy weather. Not very science-fictiony, perhaps, but it's important not to completely forget the low-tech solutions.

[Regarding your plant: my first thought, as an amateur biologist, is that a single species, no matter how well engineered, is unlikely to be able to take over everywhere- being well adapted to one environment inevitably involves design choices that reduce the ability to thrive in others. You could develop multiple strains for multiple environment types, of course. My second thought is of mutations occurring to remove the plant's vulnerability to the "control chemical". Pesticide resistance always evolves, and fighting with natural selection tends to be a losing battle]

[Stone Dog]

Honest question, is lime necessary for ALL mortar or just GOOD mortar?

[Anaraxes]

Originally Posted by Varyon

Of course, lack of fossils also means a general lack of lime, which means a lack of cement (to say nothing of asphalt)

If you have infinite free energy and you can grow plants, you can make all the asphalt you want. Petroleum's really useful only because because it's already made and sitting in the ground. But if you want hydrocarbon sludge, your energy can turn your biomass into that without too much fuss.

Originally Posted by Stone Dog

Honest question, is lime necessary for ALL mortar or just GOOD mortar?

There's Portland cement. Or more modern, higher-tech "mortar plasticizers". Here's one that says it's "lignin-based", which means you make it from woody parts of plants. But there's lots of them on the market.

The lime is for workability and improves resistance to water seeping through. It's not for adhesion or strength. (Reduces strength, actually, which is sometimes considered a good thing, particularly if you're restoring historic buildings with weaker bricks. You want the mortar to give before the bricks do.) So it really depends on what your definition of "GOOD" is.

[Varyon]

Originally Posted by ravenfish

The simplest solution for roads-without-asphalt is of course dirt roads- during periods when there isn't rain to turn them to mud, they can function remarkably well, considering. A layer of gravel can allow them to continue functioning even in quite rainy weather. Not very science-fictiony, perhaps, but it's important not to completely forget the low-tech solutions.

Indeed. Gravel roads may well be a good solution in environments where the vine isn't an option.

Originally Posted by ravenfish

Regarding your plant: my first thought, as an amateur biologist, is that a single species, no matter how well engineered, is unlikely to be able to take over everywhere- being well adapted to one environment inevitably involves design choices that reduce the ability to thrive in others. You could develop multiple strains for multiple environment types, of course.

My thoughts here were that a big part of being adapted for a given environment is being adapted to the presence of other organisms. But, until other Earth life moves in, that's not the case here - I'm thinking the life on the settled planets tends to be roughly pre-Cambrian, and as noted is rapidly outcompeted and displaced by Earth life. Essentially, humans very shortly cause worldwide mass extinction on any planet they settle. But multiple strains, designed for a variety of environments, is probably a good idea.

Originally Posted by ravenfish

My second thought is of mutations occurring to remove the plant's vulnerability to the "control chemical". Pesticide resistance always evolves, and fighting with natural selection tends to be a losing battle]

That is indeed a concern. One advantage to an engineered organism is that you can basically program in a biological "kill switch" if some traits get mutated, and you can also design the repair mechanisms for the organism's DNA to be much more effective. For the "kill switch," you can have a system that basically probes the control system to make certain it hasn't mutated, and further systems that probe that system as well as each other for validity, resulting in a whole system where everything has to mutate in just the right way all at once to actually give you runaway growth. Such wouldn't evolve, because it would essentially lock the organism into a state from which it couldn't evolve out of (and so is an evolutionary dead-end, meaning once the state it has hyper-evolved for isn't in play, it dies out).

Originally Posted by Anaraxes

If you have infinite free energy and you can grow plants, you can make all the asphalt you want. Petroleum's really useful only because because it's already made and sitting in the ground. But if you want hydrocarbon sludge, your energy can turn your biomass into that without too much fuss.

While there's no practical limit to how much energy can be extracted from hyperspace, it's not free - you need to build and maintain the power plants, and there's a limit to how many you can have running in a given area before the heat pollution (they heat up while running - they're actually the same technology as the shield systems in starships - then use a heat engine to dump that heat into the atmosphere, generating electricity in the process) of the power plants becomes problematic. But, yeah, one of my earlier ideas was a rapidly-growing plant engineered to produce a great deal of biomass in very little time, then processing that into the above biofuel slurry (or hydrocarbon sludge, as you call it) to take the place of crude oil. But then I was thinking, might it be possible to skip the middleman, and actually have the plants themselves serve as the road? And, while considering the fact the plants would need to be cleared out for building/growing other stuff, I first thought the waste could be processed the same way... then considered it might be possible to have the plant turn itself into that slurry. And so, here we are.

[ravenfish]

Originally Posted by Varyon

My thoughts here were that a big part of being adapted for a given environment is being adapted to the presence of other organisms.

Even without any other organisms, there's factors of temperature, water, sunlight and so on, which are if anything more important to a plant-type organism. (It occurs to me that, if you want to use a single strain, you could give the plant multiple sets of genes for multiple climates and have different ones get activated early in development depending on what the plant is exposed to.)

Originally Posted by Varyon

One advantage to an engineered organism is that you can basically program in a biological "kill switch" if some traits get mutated, and you can also design the repair mechanisms for the organism's DNA to be much more effective. For the "kill switch," you can have a system that basically probes the control system to make certain it hasn't mutated, and further systems that probe that system as well as each other for validity, resulting in a whole system where everything has to mutate in just the right way all at once to actually give you runaway growth. Such wouldn't evolve, because it would essentially lock the organism into a state from which it couldn't evolve out of (and so is an evolutionary dead-end, meaning once the state it has hyper-evolved for isn't in play, it dies out).

Even if you can make the kill-switch truly unable to mutate (and, so far, the number of times pesticide manufacturers have said "the system we are targeting is too fundamental to the organism for it to change" is substantial, and the number of times they have been correct is zero), you'd have to stop the plant from evolving completely unrelated systems to deactivate, block, or remove the compound. Plus, having the "kill switch" be completely unable to mutate is just asking for some pathogen to target it and wipe the plants out mono-culture style. Still, if you want to say "TL10 bioengineering makes it possible", no one alive today can say you are wrong- plus, when the one-in-a-billion failure eventually occurs and the kill switch stops working, you get a free adventure hook.

EDIT: Of course, even if the plant can't always be killed off with chemicals, the settlers can always clear land the old fashioned way with hatchets or the new old fashioned way with chainsaws and unlimited energy.

[Rolando]

I think it sounds good, of course it may have some hiccups with real science but it sounds sciency enough for me and most players. And that is what a sci fi game is about mostly, having cool technologies and weird planets and developments is part of the feeling of your game and story you are planing.

I think you may have other simpler solutions, like gravel or synthetic plastics, maybe made with bio-manipulation of plants go hand in hand with the super vines alternative.

Maybe the vines are used when there is time and less budged but if a faster solution is needed other methods are used.

The fact the plants may mutate (maybe because of something unknown in a planet) is adventure material.

[Curmudgeon]

Originally Posted by Varyon

Thinking about my Harpyias setting a bit recently, I find myself returning to the issue of roads. One aspect of Harpyias is that all of the colonized planets are relatively young, such that those that can support life have only recently (from a geological perspective) begun to harbor it. In addition to this meaning all life on such planets is rather simplistic (to the extent that Earth life supplants it pretty much immediately), it also means there are no fossil fuels or the like to draw on. For energy, this is essentially a non-issue - energy tends to be generated planet-side using superscience power plants that essentially steal energy from hyperspace (in space, where heat engines don't work quite as well due to lack of a convenient atmosphere to dump into, solar tends to be the primary source).

Of course, lack of fossils also means a general lack of lime, which means a lack of cement (to say nothing of asphalt), which means roads aren't so easy to make. Additionally, I want a lot of areas to have a bit of a "frontier" feel to them, meaning established roads are unlikely, but want wheeled electric vehicles to be common and useful.

An idea I had, and would like to run by the forum, is a kind of genetically engineered plant. It is essentially a vine with a shallow root system, and it is designed to rapidly grow in a manner where each individual vine is tightly wrapped and packed in with others, forming a hardy surface that can stand up to being driven over by even rather heavy vehicles (electric equivalents to modern semi tractor-trailers, for example), yet is flat enough to give a smooth ride. It wouldn't be quite as resilient as, say, modern asphalt, but would make up for that in the fact that it would be self-repairing. The plant would be controllable by chemical means - trace amounts of a specific chemical (something rarely - or never - encountered in nature, cheap to manufacture, and largely-harmless) essentially serves as a "don't grow here" signal to it, while larger concentrations trigger it to destroy itself. Upon said signal, the vines would first become weak and brittle, then slowly break themselves down into a sort of slurry of biofuel.

Essentially, upon colonizing a new world, humans would spread the seeds for these vines over the surface. The vines would rapidly cover the exposed continents (at least, in areas where the vines can grow, although I intend them to be hardy enough that pretty much if any plant can grow somewhere, the vines can). When humans settle into a new area, they spray the control chemical over areas where they need to get rid of the plant (for growing crops, building structures, etc), then either wait for it to become weak and pull it up or wait a bit longer for it to turn into a biofuel slurry and simply burn it. Keeping the soil with trace amounts of the control chemical prevents it from regrowing, and now you end up with a world that's covered in oxygen-producing greenery that also serves as roadway (and even smooths out drops and rises). The biofuel slurry wouldn't be very useful as an energy source - the superscience power plants are more efficient and less polluting than internal combustion engines, and most things are powered by superscience powercells that have a higher energy density than the biofuel - but may be able to be processed into plastics, fertilizers, etc (covering some of the other issues the lack of fossil fuels would cause).

Does this sound feasible? Is there a simpler solution? Are there problems I'm not foreseeing here? The society in question is very roughly around TL 10 (it's really more TL 8-9 with a healthy heaping helping of superscience), if that helps.

Dirt and gravel roads aside, there are other options for roads without paving. The two options we saw a lot of on Earth, until metaled roads became a thing for bicyclists were cobblestone roads and corduroy roads. Neither gives a smooth ride. For those unfamilar with them, corduroy roads were made by felling trees, cutting them to length and then laying them out side by side perpendicular to the direction of travel. They were the primary road style in colonial Canada during the French regime. If labour and the availability of metal tools aren't issues, you could split the logs and lay your corduroy roads flat side up. Longer split logs could be laid flat-side down along the edges to create a border that keeps the logs relatively flat to each other.

Bio-engineering might be up to making a plant that's effectively a corduroy road. It's probably a ground-hugging vine, but there's probably an option that'll turn it into an elevated rail for high speed transit, or maybe for a low-speed monorail.

[Donny Brook]

Since it can be genetically engineered, it might be more efficient to purpose-plant the roads rather than scatter the plant and have to weed it back. Think of something like bamboo engineered to grow horizontally and only to whatever length you want for the width or your roads.

You might end up with sort of living versions of corduroy roads.

[Anthony]

Originally Posted by Varyon

Indeed. Gravel roads may well be a good solution in environments where the vine isn't an option.

Gravel roads work in a huge variety of environments, it's just a question of how often you need to use a grader to flatten them out again.

The core problem with plant-based roads is that traffic is really good at killing plants, there's a reason any regularly used path is plant-free.