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I came across mentions of "gilded roads" and thinking of the Yellow Brick Road of Oz, I'm wondering how sensible for walking a fantastical road made of literal pure gold would be.

Just for walking, with or without shoes as is better. No horses, no cars, just feet, but the gold doesn't have to be smooth, could be in the form of pavers, although I don't know how long they'd last if I make them out of solid gold, whether it would eventually merge with all the other gold into a solid mass.

If, for some reason, a gilded material would be better, instead of solid gold throughout, that's also useful to know, and if so, what the most expensive material to gild for this would be, like covering a solid diamond surface in gold, or something, for more fantasy frivolity and conspicuous consumption.

Basically wanted to know if I could have Oz's Yellow Brick Road replaced with as pure a gold as I could, either as pavers or as a solid block, and still have Dorothy, or anyone else, walk down it.

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    $\begingroup$ What's the metric of success? Can a person walk on a gold brick surface? Sure. Would it be much different from asphalt? No. Would hot sunlight melt it? No. Would it soften enough on a hot Arizona day to make a difference? Not really. Would it be easier to lay down than asphalt? Probably not. Would it poison people? No (unless eaten regularly). Are you asking from the perspective of the Real World? Not our problem - the real world has already been built. Are you asking from the perspective of your imaginary world? Great! What's the difference between it and the Real World? $\endgroup$ Commented Jan 13, 2025 at 4:58
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    $\begingroup$ It'd be awful for walking... complete gridlock as you're trying to get to your destination, what with everyone hunched over blocking the way as they were prying out gold bricks. (Or worse, a bunch of singing and dancing munchkins throwing a parade.) $\endgroup$ Commented Jan 13, 2025 at 15:12
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    $\begingroup$ What keeps looters from making off with the gold bricks? That's my first question. Can you imagine the frustration of the brick-layers, and the party financing the project? I guess it's a pretty amusing scenario, when you consider the futility of the endeavor. "Whose idea was this, anyway?!" "Someone back on Earth - a user on Stack Exchange..." $\endgroup$ Commented Jan 13, 2025 at 17:32
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    $\begingroup$ It's probably not what you mean, but it has often been observed that the streets of Kalgoorlie were literally "paved with gold" because the mineral calaverite (which contains gold) was mistaken for iron pyrite (which does not), and was used extensively as aggregate for building roads and other construction. Once the mistake was realised there was something of a second gold rush. (And actually, in the Kalgoorlie area there are pyrites that contain gold as well, so even if they hadn't made that mistake, it still might have happened, it just wouldn't have been noticed for much longer) $\endgroup$ Commented Jan 13, 2025 at 17:59
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    $\begingroup$ I'm not sure people would want to make off with the gold bricks, since it this world it seems that gold is very common and not that valuable... $\endgroup$ Commented Jan 13, 2025 at 19:19

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If you start from the perspective of gold not being a precious metal, this is a functional idea. What you want to look for is the Brinell hardness. That's where you press a super-hard sphere into the substance under a specific amount of pressure to see how far it'll sink.

Here are a few common values:

  • Lead: 5
  • Pure Aluminum: 15
  • Hardened Aluminum: 75
  • Mild Steel: 120
  • Tempered Steel: 400-700

On this scale, pure gold rates 190. If gold were that common, however, you'd likely have wear resistant alloys. You could also embed sand into the surface to absorb the worst wear. You wouldn't have to worry too much about it being dented, unless someone dropped an anvil on it.

As you suspect, horse shoes and the steel rims of wagon wheels would quickly beat the surface up, making ruts.

You would definitely not want to do a gilded material. Gold leaf is incredibly thin, and would wear through rather quickly.

Regular travelers might have to worry about gold toxicity. In our world, the presence of gold usually accompanies the much greater presence of more harmful metals like mercury and nickel.

Update

Based on Chris's comment, I searched the web for references to the Brinell hardness of gold, and got a very wide selection of answers, documented here.

Even though its number is significantly lower than the others, I'd be inclined to accept the MatWeb fine, cast number of 33 because it's the only one that specifies the alloy quality. I'm pretty sure that would be OK for walking, but they might want to alloy it to make it hail-resistant.

I'm thinking someone should update the Wikipedia page.

Update 2

After a little more research it appears that, even for pure gold, the hardness varies based on tempering and mechanical treatment (e.g., beating or rolling) so there's quite a bit of variability in those numbers. You'd think that they had a standard for this.

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    $\begingroup$ Gold isn't toxic... unless you're a cyberman. $\endgroup$ Commented Jan 12, 2025 at 22:28
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    $\begingroup$ @elemtilas Quite possibly, but the OP hasn't said that this gold road is anything but pure gold. The toxic elements could easily have been left elsewhere. $\endgroup$ Commented Jan 13, 2025 at 4:16
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    $\begingroup$ There already are wear-resistant gold alloys. If you've ever used a card edge connector--like those used on m.2 SSDs, PCI(e) cards, all the way down to NES cartridges--you've encountered such a "hard gold" finish in person. They're a thin layer of (I think) usually either a gold-cobalt or gold-nickel alloy over a thicker layer of nickel; the alloy is 90-ish% gold but much more wear-resistant than 100% gold, and the layer of nickel acts as a barrier to prevent it from dissolving into the copper below. $\endgroup$ Commented Jan 13, 2025 at 6:14
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    $\begingroup$ Metallic gold isn't toxic because its very inert. But some problems have been experienced with medical use of gold compounds such as sodium aurothiomalate where the gold compounds react with tissues forming metallic gold. Your road should present no problems. Read more at: forum.facmedicine.com/threads/… $\endgroup$ Commented Jan 13, 2025 at 9:48
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    $\begingroup$ Pure gold having a hardness greater than mild steel doesn't feel right at all (given how easily 9 carat gold dents/scratches, and that's harrder than pure gold). I think you might be mixing up hardness scales, or the different indenters used in Brinell testing. See Wikipedia: hardness of the elements $\endgroup$ Commented Jan 13, 2025 at 15:36
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I looked up and compared some more properties of gold (or other metals) compared to asphalt.

Hardness

Here I simply refer to the other answer from Robert Rapplean.
-> This should work.

Friction

I found a comparison table for friction between some different materials (unfortunately not in english so I omit the link).
The friction value on a road (rubber to asphalt in dry condition: 0.7 to 0.9) is much higher compared to metal (rubber to cast iron in dry condition: 0.5).
The gold road will be more slippery than asphalt, probably even more when it is wet, but it should be walkable. It may be better when you have a rugged surface instead of a flat one, but this would lower the durability of the surface.
-> I guess more slippery but OK

Heat behavior

The entire heat conducting mass will act like one single block including heat storage and heat expansion. Fortunately the temperature should be the same as the average ground temperature.
You probably need to make some gaps for the heat expansion, like it is done for rails or like road stones.
Better don't lick the road on a cold winter day.
-> This should work

Reflection

If you have a not so shiny and a rugged surface then this may be fine. With a very flat and shiny surface on a sunny day, you will need good sunglasses sunscreen and a lot of drinks.
-> Maybe unpleasant on some days but doable

Weight

This should not directly affect the walkability, but I guess the constructors of the road have to do some countermeasures to ensure that the road doesn't sink into the ground and remains flat.
On some areas this problem already exists for normal roads, a gold road will be more problematic. But if you know how to build a metal skyscrapper then this should be doable in most areas.
Gold has around eight times the weight of asphalt (19.3 t/m³ vs. 2.4 t/m³)
-> Should be doable

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  • $\begingroup$ all your answers seem to amount to "you might be able to do this, because it's only slightly worse then what we use currently." If gold is a common material in this world, as OP said in comments, then there would be no reason to use gold just to show off since it's nothing special in that world. Given that one has to ask why anyone would pick gold as a building material in place of the same materials we currently use which are superior options in every measure you listed. $\endgroup$ Commented Jan 13, 2025 at 21:16
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    $\begingroup$ @dsollen maybe someone liked the color? Or the other materials are not as readily available? $\endgroup$ Commented Jan 13, 2025 at 23:42
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    $\begingroup$ @dsollen, gold doesn't get any less shiny just because it's common. $\endgroup$ Commented Jan 13, 2025 at 23:53
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    $\begingroup$ @dsollen The question is just about whether it is possible to build a road out of gold and if one can walk on it, not whether it is the best of all options. I would definitely recommend to use something rock-based. $\endgroup$ Commented Jan 14, 2025 at 12:02
  • $\begingroup$ Gold is one of the best conductors. If your gold road is built in an area with a regular amount of thunderstorms, and do not take countermeasures, some travellers may be electrocuted in every thunderstorm. Countermeasures could be a Faraday's cage, embedding in an insulator (like asphalt) or to marshal a road-ban in bad weather conditions. $\endgroup$ Commented Jan 21, 2025 at 13:48
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Problem #1: Too dense

Pavers (bricks used to make a road) sink into the underlying soil much more easily that large contagious slabs of concrete or asphalt. This means that you need to make sure that the density of your pavers is not so high that they sink into the underlying material, otherwise every time you get a heavy rain, the bricks will displace a bit of the underlying mud on top of the road. For this reason pavers are normally made using low density aggregates. Your average paver has a density between 1.6 to 2.4 g/cm^3 whereas your average subsoil which you would lay a brick road on has an average density of 1.6 to 2.0 g/cm^3.

So, going a bit above the density of the subsoil is fine, but gold has a density of 19.3 g/cm^3. So each gold brick will weigh as much as 10 paver bricks stacked up on top of eachother meaning your road will sink 10 times as fast making it a maintenance nightmare. This problem gets much worse if you are in a hilly or wet environment. A gold brick road built over a hill is far more likely to want to slide down hill, Earthworks designed to make level terrain for a road will need to be built wider and or be better reinforced, and bridges will be harder to construct using such a heavy material.

Instead of gold bricks, I would suggest gold tiles. Lay down a large solid slab of concrete, (because it give subsoil fewer places to rise though) and then tile the gold tiles on top because being thinner will reduce the surface pressure. It will still give you the impression of a gold brick road, but without all of the mechanical shortcomings that will cause it to sink and become untraversable.

Problem #2: Too much scrap valuable

I'm not saying your road is too valuable to be made... I'm sure someone can afford it. I'm saying it is too valuable to keep in good repair. A standard 10x20cm paver is going to contain about 19kg of gold which is worth about much as the average person will make in their entire lifetime; so, to simply leave a bunch of these things lying around on the ground for anyone to take is going to be too tempting to keep people from stealing them. If you assume your gold brick road is actually worth anywhere near as much in your world as it is in ours, your bricks will go missing so often that it will be a nightmare to keep replacing them... and if your road always has a bunch of missing bricks, it's not going to be good to walk on.

If they are not worth enough to be worth stealing, then it's not really a display of opulence to make a road out of them.

If you really want to make an opulent road that is worth a lot, but not worth breaking into pieces to sell off, you need to either build it in a perfect utopia where everyone is so moral that they choose to not vandalize it or you need to make it so that it's value only exists as its whole, not the sum of its parts. For this I would recommend making a mosaic road where it is not the tiles themselves that are worth a fortune, but the artwork that they create. So the bricks may just be glass tiles with a faux gold leaf backing, but they are so masterfully laid that they create beautiful images making the whole road a priceless piece of fine art.

But IF you could maintain it, gold is a perfectly fine material to walk on

There are only 2 properties worth noting when deciding if a material will make a suitable surface to walk on: Yield Strength and Traction.

A few other answers have said that the low hardness of gold means it will wear out over time, but that is not actually a major concern because gold is so ductile. Yes, it will scratch easily, but when gold scratches it deforms, it does not break up and erode. Having bricks that slowly get scuff marks over time will not make it a bad surface to walk on, but sinking into it will which is why you need to actually look at its yield strength, not its hardness.

At about 2.5 tons per square inch for solid gold or 7-13 tons per square inch for common gold alloys, gold bricks are more than capable of supporting your weight without squishing. So while it is soft enough to easily scratch with a pointy tool, under the strain of something the size of a human foot, it would take many tons of weight to actually squish a gold brick.

Also, gold is not a particularly slippery material, even when polished smooth. Like most inert metals, it does not form the oxide coating that tends to cause reactive metals to self lubricate. Furthermore, it is hydrophobic meaning that it also will not become slippery when wet like many kinds of non-porous tiles do.

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    $\begingroup$ I like the idea of a glass-covered gold, even if the gold price is very low in this world. If yinz chose the right kind of glass, you would find that youse had much less abrasion due to dirt tracked onto the road, animal hooves, and other hard objects that you guys can't keep from interacting with the surface. Otherwise even if ye have no costs but labor and shipping, you lot will be paying a fortune to keep youns road in good repair because gold is so soft and malleable. $\endgroup$ Commented Jan 14, 2025 at 0:20
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    $\begingroup$ I'm from a place where people often steal entire metal bridges... So I believe that a golden road would need to be very well guarded. $\endgroup$ Commented Jan 14, 2025 at 11:11
  • $\begingroup$ @MarcoMarksman I doubt you would need to worry about random pedestrians stealing the gold from the gold road... The bricklayers would beat them to it. $\endgroup$ Commented Jan 14, 2025 at 17:42
  • $\begingroup$ alternatively have and underlayment of aggrigate on he road like all the best roads. Much harder to displace AND prevents potholes. $\endgroup$ Commented Jan 14, 2025 at 21:28
  • $\begingroup$ Glass covered tiles or paver stones is likely the best idea. Either with the gold on the back or throughout the middle. The gold would still wear down if it is on the bottom side, but the distribution of weight and the inability of abrasives to get in contact with the gold would make that a lot less fast. And we have already invented enough forms off glass that can hold the weigh, and resist abrasion. $\endgroup$ Commented Jan 15, 2025 at 14:50
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If, for some reason, a gilded material would be better, instead of solid gold throughout, that's also useful to know, and if so, what the most expensive material to gild for this would be, like covering a solid diamond surface in gold, or something, for more fantasy frivolity and conspicuous consumption.

If you enjoy bouldering a solid gold road will provide you with entertainment on your walk as you climb through the bridges that collapsed under the weight.

For the ones that miraculously didn't fail, in winter they'll also provide you with far more chances to sit and relax as you slip on the black ice that will more readily form since there is no earth under a bridge to provide heat and you just built one that is basically a heat sink.

If you're thinking you don't remember any bridges in the movie understand, most bridges don't look like the Golden Gate. You probably crossed over 2 dozen on your way to work and didn't even notice.

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Assuming the road was made, and that potential travelers could be pursuaded that the destination they would reach was, in fact, not the infernal realm, then it would be neither more nor less suitable for travel than the large steel plates used to temporarily allow safe travel over an excavation.

A metal surface tends to become impassibly hot in full sunshine. A metal surface tends to be unreasonably slippery when wet.

I believe that travelers would learn covering the soles of their shoes with alternating strips of sandpaper and gum adhesive allowed them to travel the gold brick road both safely and exceptionally profitably.

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