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Max™
2014-06-21, 01:12 AM
Grabbed this from physicsforums (http://www.physicsforums.com/showpost.php?p=2424022&postcount=7):

Say for example you have a 1-mile stretch of 2-lane road you want to keep snow free even during a fairly slow snowfall of 1 in/hr (heavier storms can be 6 in/hr). We will say the road is 7.5m (24.6 feet) wide, the snow falling has a density 8% that of water, and the snow falling is excatly 0 degrees C which means we only have to deal with water's enthalpy of fusion.

1 in/hr of snowfall correlates to 311 m^3/hr over a 1-mile stretch of road, or 25,000 kg/hr of snow. If we want all of this snow to melt right away and not accumulate, we need to put enough power through the heating coils to melt the snow as it falls. Given that water's enthalpy of fusion is 333.5 kJ/kg, that equates to a necessary power throughput of 2.3 MW for a single mile of 2-lane highway. Obviously the power requirements are substantial, at about 1.4 kW/m for 1 in/hr snowfall.

So say hypothetically tiny town X wants to completely get rid of their snow plow fleet and replace it with heated roads that are powered by wind turbines. They have a total of 5 miles of road, all 7.5m wide 2-lanes, that they want to be able to handle a maximum of 4 in/hr of snow. That would mean they would need a total power input of 46.1 MW to heat the entire road system during heavy storms (4 in/hr), and 11.5 MW during light storms (1 in/hr).

AgentPaper
2014-06-21, 02:34 AM
Ok, decided to just go ahead and do the math on this:

Each tile is about 1.2 square meters. Looking at average annual snowfall, 1.2 meters (48 inches) also seems to be about average for the higher end of snowfall in the USA. So that means, we have a 1.2 meter cube of snow that needs to be melted each year. The density of water is just under 1000kg/m^3, so that translates easily to 1,200kg of water.

Of course, snow isn't nearly as dense as liquid water, though, and according to wikipedia on average snow is about 8% water, so that's actually only 96 kg of snow that needs to be melted. Using the numbers posted above, that's 32,000kJ of energy required to melt all of the snow that accumulates over the year.

According to their FAQ, their panels currently produce 36 watts, but that will go up to 52 for the real deal, so I'll use that. 52 watts means 52 joules per second, so that means it would take ~615,000 seconds, or a bit over a week, to produce enough energy. Of course, that's assuming full generation 24/7, so in reality it would probably take 2-3 weeks to generate that power, but I think that makes it pretty clear that the panels will be more than capable of generating enough power to heat themselves.

Of course, any power used to heat the panels is power not being used to power homes, but we can look at this another way as well: 1 kJ is equal to ~0.00028 kilowatt hours, so our 32,000kJ is equivalent ~9 kilowatt hours. Going by this (http://www.eia.gov/electricity/monthly/epm_table_grapher.cfm?t=epmt_5_6_a), that amounts to ~75 cents of power used per square meter each year.

Unfortunately, I couldn't find any solid numbers to compare that 75 cents to, but using some quick and dirty math*, I estimated 30 million dollars annually to melt snow using the above numbers. I couldn't find any numbers for the total annual cost of snow removal, but from the numbers I've seen while looking for that mystical number, 30 million is chump change.

Of course, this ignores the extra power required to offset loss of heat into the air, but even if that increased the energy expenditure by an order of magnitude, we'd still probably be saving money by heating our roads rather than plowing and (especially) salting them. And that's not even getting into the economic costs when people can't drive to work because they're waiting for the road to be plowed, or don't want to drive on roads covered in salty, slushy ice.

From what I can tell, the main reason we don't have all of our roads heated is because of the infrastructure costs associated with installing and maintaining them each year, which is a big upfront cost since you have to tear up the road surface to put the pipes in. With the panels, you just need to slap on a heating element to the existing structure and you're good to go.

*Specifically, I assumed that 25% of the United State's 61,000 square miles of paved surface sees 48 inches of snow, and the rest none.

Max™
2014-06-21, 02:53 AM
http://www.wcvb.com/news/local/boston-south/cape-cod-snow-removal-costs-piling-up/23892348

Looks like Massachusetts alone spent ~\$40 million after the storms this winter, and 2013 was quoted a value of ~\$92 million.

So even worst case and tripling the costs for the electricity you calculated, you're getting about as much as one small state spends on snow removal in one year?

Sounds good to me.

Unstated bonuses of having these elements present: places like Memphis don't have stuff like plow crews and salting equipment on ready use, so when we do get bursts of ice it is a HUGE problem, I'm not sure how much is spent on accident clearing, repairing power lines, attempting to clear roads, lost productivity, and so forth... but being able to drain a bit of juice and have the roads simply not ice up... PLUS not have to worry about downed power lines anymore?

Ever sat through a few days of freezing temperatures waiting for power to get restored? It ain't fun, and they aren't good at dealing with ice/snow down here due to how randomly it shows up.

2014-06-21, 08:09 AM
Ok, I finally had time to go through the Clearing the air article they gave:
1. The very emotional beginning rises a few red flags for me - starting a reply with a dismissive haters gonna hate is never a good thing to do.
2. They never answered, why they decided to put the solar panels on the roads - there are things about current road maintaince costs without reasonable claims, why putting the solar panels on the roads instead of a more efficient design would help. Also a lot of talk about other features, which have nothing to do with solar panels.
3. IIRC the cost estimates for the high quality glass itself do go into trillions of dollars (correct me if I'm wrong), when we are talking about full road coverage. Since it's already mass-produced, the prices won't go down by much. If the operation goes into full swing, the prices may even go up due to high demand. Plus, they don't have the numbers to claim, their roads will be cheaper then current ones. Therefore they shouldn't claim cost savings, if they can't back it up yet.
4. On the costs of asphalt road maintaince they only gave country-scale big numbers instead of per lane-mile, which would be much easier to compare. Even more so they should focus on comparison with their proposal. Again no data to support their claims.
5. Considering the road heating they again gave no cost-estimates on the proposed road heating system. At the very least they should do the math on the minimal electricity spendings as people in this thread did.
6. I'm baffled that anyone claimed that glass is soft in comparison to asphalt. I can understand the claim that glass doesn't take vibrations well (which is true) or that the traction-giving surface won't last very long (which really needs to be tested), but this was indeed silly.
7. Concerning shadows they forget that car coverage on the roads can be substantial (especially in the cities), but they did answer the particular claim

In short: too emotional for my tastes and too low on hard data. If they don't have the data yet (which is understandable), they shouldn't make such strong claims.

As for the gaps, you do know that neither concrete or asphalt are remotely smooth on any scale smaller than a foot or so, and in fact a part of concrete road maintenance is grinding ridges into the road for traction each time they wear down.

Concrete roads are often designed with gaps every so often to allow for expansion without cracking the whole block, not to mention things like bridges and such with built in expansion gaps, often using a different material like steel for these locations.
There is a vast gulf of difference in scale of those irregularities between asphalt and tiles. Asphalt stops being smooth on a scale of less then an inch or so with the height differences being even smaller. Concrete grooves on the other hand are often made in line with the direction of travel, which means they don't contribute to vibrations. If the grooves are made perpendicularly to the irection of travel, they are purposfuly created in random intervals to prevent vibrations from accumulating. I don't have the data on where perpedicular tining can or can't be used. And the dillatations are few and far in-between. As for expansion gaps on the bridges, take a look on how they are made - they are teeth-like in shape to prevent the gap from affecting the cars much and you still distinctly feel them.

Gaps or no gaps, the proposed surface for the tiles is bumpy on it's own.

As for the black silicon you mentioned earlier: it is relevant to solar panels, but such fine structure (details on the scale of half a micrometer) wouldn't last long if exposed to mechanical wear. You would need to coat it with something more resistant, which might rise reflectivity again and defeat the purpose of the design. Besides, the proposed solar tiles already rely on a specific surface texture to solve a different problem (traction). You might possibly use non-reflective surface between the knobs, but the costs for such a glass tile would quite possibly sky-rocket.

One general point, I might add or reiterate: the porposed system is IMO needlesly complicated, which means it cotains way too many points of failure some of which would cause damage to other parts of the system, which generates costs. For example: it is vital for the tiled road survival that the heating and water-disposal system works. If the water is allowed to freeze, things will take an ugly turn and depending on designs details might cascade over a large area. Passive solutions are pretty much always cheaper and more reliable.

After going through and doing research into various aspects of road construction and material properties I was still faced with "yeah, but tiles will move around like in that video", so at that point the correct response is to ignore it, which I didn't do, because I continued trying to explain the issues with that argument for far too long, it is hard to realize that I'm getting nowhere and move on.
Point of order: you gave a research on asphalt wear, which defeated your own argument. From the whole issue of road damage you focused on one point (asphalt wear), which according to the very data you have given never ammounts to maintaince costs. You completly ignored arguments based on mechanics concerning stress loads and their distribution through different road layers. You also forgot to account for wear damage, where it actually might be important - if you rely on texturing for traction, then you cannot afford to lose the outer layer of the road. If they can design a machine to resurface the tiles directly on the road, then it won't be any more complicated then concrete tining. If you need to replace the tiles due to loss of texture, you are looking at substantial increase in operation costs.

Also relevant: I hope they answer the questions mailed by a kind person from this thread.

Max™
2014-06-21, 08:57 AM
As I said, after researching these subjects, attempting to explain why the argument presented with the video as some sort of illustration was flawed, and so on, it's ultimately nitpicky edge cases.

The silicon thing was for the surfaces of the cells themselves which are underneath the glass, not directly applied to the glass itself, btw.

2014-06-21, 09:32 AM
As I said, after researching these subjects, attempting to explain why the argument presented with the video as some sort of illustration was flawed, and so on, it's ultimately nitpicky edge cases.
And as many people have said: there are no edge cases on such scales. And again: argue against the argument given and not some animation. The point stands regardles of the video.

The silicon thing was for the surfaces of the cells themselves which are underneath the glass, not directly applied to the glass itself, btw.
Which means, it's not that useful, since the outer layer will be reflecting the light anyway. It might help, but not by much.

warty goblin
2014-06-21, 10:29 AM
There is a vast gulf of difference in scale of those irregularities between asphalt and tiles. Asphalt stops being smooth on a scale of less then an inch or so with the height differences being even smaller. Concrete grooves on the other hand are often made in line with the direction of travel, which means they don't contribute to vibrations. If the grooves are made perpendicularly to the irection of travel, they are purposfuly created in random intervals to prevent vibrations from accumulating. I don't have the data on where perpedicular tining can or can't be used. And the dillatations are few and far in-between. As for expansion gaps on the bridges, take a look on how they are made - they are teeth-like in shape to prevent the gap from affecting the cars much and you still distinctly feel them.

It's also worth considering how a glass topped solar panel fails, vs. a slab of concrete or asphalt. If a slab of concrete in a concrete road cracks, it's almost certainly still usable as a road over the short term. It's a less comfortable road, a less good road to be sure, but it still works. Same thing with asphalt. Damn things crack every spring if you live in a place with freeze/thaw cycles, and although they may be unpleasantly bumpy until they get releveled and patched, they still work.

What happens when a tile breaks? Do you end up with chunks of tempered glass spraying out from under people's tires? That could be a problem. If one tile breaks, how does that effect the wear of the tile next to it? Is the lane simply unusable until the tile is replaced? There's a lot of areas where that could shut down roads for hours, routinely.

Now I don't know if that's how the tiles fail, but I think it's a question worth asking.

Karoht
2014-06-21, 11:41 AM
Ok, decided to just go ahead and do the math on this:
Good post, sorry to snip it.

The city of Calgary (where I live) spends gobs of money plowing roads, and even then they can barely keep up the main roads, the secondary roads and side streets get all but ignored until there is a melt. We also have one of the largest snow removal budgets per capita in Canada, if not the largest.
If heating the roads was enough to loosen the snow to the point where the plows could go over a given area less, especially the main roads, that would be a huge help. As for the secondary roads and side streets, it might mean that those roads would actually get some attention.

Speaking purely from a quality of life perspective, that would be huge.
Worth the expenditure? Still up for debate of course.

Mando Knight
2014-06-21, 12:00 PM
What happens when a tile breaks? Do you end up with chunks of tempered glass spraying out from under people's tires? That could be a problem.
It would have to shatter into many small fragments, like safety glass, in order to not be a hazard. However, getting that, the desired optical properties, and the desired tensile strength may drive the cost of the glass even higher.

Max™
2014-06-21, 01:22 PM
The glass was supposed to be handling loads of something like 200,000 lbs, wasn't it?

Karoht
2014-06-21, 01:38 PM
The glass was supposed to be handling loads of something like 200,000 lbs, wasn't it?Manufacturing fault, materials fault, catastrophic failure due to unlikely but plausible circumstances, (strawman) theft/vandalism, etc.
Like all things mass produced, they're going to be made by the lowest bidder (Made in China, Made in USA), things happen. Life happens.

A meteor falls from the sky, and smashes a hexagon shaped patch of road (7 tiles total). How driveable/undriveable is that area?

Max™
2014-06-21, 01:41 PM
How driveable or not would any road be in the meteor scenario?

2014-06-21, 01:43 PM
The glass was supposed to be handling loads of something like 200,000 lbs, wasn't it?
It's tempered glass. Loading isn't the issue, it's sharp impact, like if for example, you drive over it in a big rig that has a hard little rock stuck in one of the tires. Tempered glass will explode if the surface is damaged like that, and while the pieces shouldn't be too sharp (there is a reason it is called safety glass), they run the risk of getting stuck in other peoples' tires, maybe even causing a chain reaction. Depends a bit on how much it has been treated though, which again, is not information they've found in themselves to release.

Or it was just produced with a small defect in it. Can't inspect that many glass pieces that well.

warty goblin
2014-06-21, 01:52 PM
The glass was supposed to be handling loads of something like 200,000 lbs, wasn't it?

Loads, sure. What about sharp impacts? For instance the other day I observed somebody hauling a trailer down the road, the tailgate of which had fallen down and was dragging on the road. Since the road was concrete, I suspect the worst thing that happened was that the impact of the sharp steel corner of the tailgate with the road had chipped the road surface a little. Still a perfectly drivable, safe surface.

If it had been glass, would it have shattered? I don't know, but it's a reasonable question as to whether a single failed catch could destroy a lot of expensive road, and potentially shut down a major roadway for an hour or so.

Or, if you live in an area with a significant Amish population, what about horses? Horse shoes already do a good number on asphalt roads, I'd imagine a team of work horses pulling a buggy would eat through a solar freaking roadway like, well, like hard steel through glass. Probably wouldn't do the horses any good either.

At the end of the day I'm not sure this idea isn't like trying to make a Swiss Army knife replace my entire toolbox. Sure my pocketknife has a screwdriver on it, but it's kinda a crappy screwdriver. And it has a knife blade, but it's not as good as my fixed bladed belt knife. It flat out lacks allen wrenches, which are handy things. Now my Swiss Army knife is still a good tool, because it's still small, cheap, easy to use, and extremely portable. But I'm not going to replace my toolbox.

2014-06-21, 02:20 PM
At the end of the day I'm not sure this idea isn't like trying to make a Swiss Army knife replace my entire toolbox. Sure my pocketknife has a screwdriver on it, but it's kinda a crappy screwdriver. And it has a knife blade, but it's not as good as my fixed bladed belt knife. It flat out lacks allen wrenches, which are handy things. Now my Swiss Army knife is still a good tool, because it's still small, cheap, easy to use, and extremely portable. But I'm not going to replace my toolbox.Doesn't mean they won't stop trying.http://www.wengerna.com/stuff/contentmgr/files/0/a45137daa224e9531cb3050458faee64/image/wenger_giant_knife.png

Mando Knight
2014-06-21, 03:05 PM
Loading isn't the issue, it's sharp impact, like if for example, you drive over it in a big rig that has a hard little rock stuck in one of the tires.
Another factor is fatigue, which will occur... and glass isn't a front-runner in fatigue strength, largely because of its hardness (compared to structural metals, it's very brittle and has low tensile strength, and macroscopic cracks can propagate very rapidly, all because of the same crystal structures that lend to glass's hardness). The tiles (and the fasteners) don't need to be designed to withstand a static load of one vehicle (which, for a load largely under compression, is easy), but for the dynamic load/unload cycles of thousands of vehicles driving over the tile every day, millions of cycles per year.

"Nailing" the tile to the ground provides an area with high stress concentrations, that will potentially see many times the nominal load, as well as form a prime location for corrosion, which makes those sites prime spots for crack generation.

Fatigue is a major design concern for road systems, especially those frequented by large vehicles (i.e. essentially every highway in the US).

NichG
2014-06-21, 03:35 PM
Another factor is fatigue, which will occur... and glass isn't a front-runner in fatigue strength, largely because of its hardness (compared to structural metals, it's very brittle and has low tensile strength, and macroscopic cracks can propagate very rapidly, all because of the same crystal structures that lend to glass's hardness). The tiles (and the fasteners) don't need to be designed to withstand a static load of one vehicle (which, for a load largely under compression, is easy), but for the dynamic load/unload cycles of thousands of vehicles driving over the tile every day, millions of cycles per year.

Actually for tempered glass, the reason cracks propagate so quickly is a macroscopic phenomenon not a microscopic one. When you temper glass you introduce residual stress. Think of it like freezing the outermost layer in place quickly when the temperature is high throughout the sample (because glass is amorphous, it will retain the particular configuration it had when you rapidly chill it, unlike a crystaline material which would be constrained by its lattice). Then, you allow the inside to cool slowly, so it shrinks down compared to the volume that you enclosed it in. Essentially the inside is constantly pulling 'inwards' on the surface, and the surface is constantly pulling 'outwards' on the inside. This helps give the material its strength, because those forces allow the entire bulk of the glass to talk with itself, so local deflections are being resisted by the entire sample and not just the structure around that point. Thats specifically what distinguishes tempered glass from non-tempered glass, and why the strength is so different between the two materials.

So back to cracks - those stresses help hold the structure together, until you nucleate a crack. When you have a sufficiently large crack then the crack tip acts as a place where those stresses can be relieved by changing the geometry. That means you get stress focusing down to the crack tip, and those stresses drive the crack tip forward at very high speeds.

An example of this phenomenon is 'Prince Rupert's Drops'. Basically you throw a glob of molten glass into cold water, and it forms a bit of a teardrop shape with an extended tail. It turns out that if you snap the tail, the entire drop explodes into microfragments due to the residual stresses.

Here's a demonstration of the phenomenon: https://www.youtube.com/watch?v=6V2eCFsDkK0

Incidentally, though it looks to be very vigorously explosive in the video, its not dangerously so. The drops are named as they are because Prince Rupert allegorically used them as a prank, getting people to hold the glass bulb and snapping the tail. It would feel like something just smacked their hand, but wouldn't actually blow their hand off or anything that extreme.

2014-06-21, 03:46 PM
Another factor is fatigue, which will occur... and glass isn't a front-runner in fatigue strength, largely because of its hardness (compared to structural metals, it's very brittle and has low tensile strength, and macroscopic cracks can propagate very rapidly, all because of the same crystal structures that lend to glass's hardness). The tiles (and the fasteners) don't need to be designed to withstand a static load of one vehicle (which, for a load largely under compression, is easy), but for the dynamic load/unload cycles of thousands of vehicles driving over the tile every day, millions of cycles per year.

"Nailing" the tile to the ground provides an area with high stress concentrations, that will potentially see many times the nominal load, as well as form a prime location for corrosion, which makes those sites prime spots for crack generation.

Fatigue is a major design concern for road systems, especially those frequented by large vehicles (i.e. essentially every highway in the US).That's essentially the same mechanism, just with crack origin somewhere else in the tile instead of the top contact surface. You'll end up with the same catastrophic failure of the tile into fragments, because of the pre-stress in the glass (unlike asphalt, which you at least have some time as the crack moves up from the bottom surface).

It's not exactly fatigue in the same sense as one has in metals, but it is an issue. I'd be somewhat concerned for the pins holding it down too, although they probably won't experience enough cycles before the the glass is too abraded.

An example of this phenomenon is 'Prince Rupert's Drops'. Basically you throw a glob of molten glass into cold water, and it forms a bit of a teardrop shape with an extended tail. It turns out that if you snap the tail, the entire drop explodes into microfragments due to the residual stresses.

Here's a demonstration of the phenomenon: https://www.youtube.com/watch?v=6V2eCFsDkK0

Incidentally, though it looks to be very vigorously explosive in the video, its not dangerously so. The drops are named as they are because Prince Rupert allegorically used them as a prank, getting people to hold the glass bulb and snapping the tail. It would feel like something just smacked their hand, but wouldn't actually blow their hand off or anything that extreme.Another video on the drops with some more explanation and some super high speed video: https://www.youtube.com/watch?v=xe-f4gokRBs

warty goblin
2014-06-21, 04:13 PM
It's not exactly fatigue in the same sense as one has in metals, but it is an issue. I'd be somewhat concerned for the pins holding it down too, although they probably won't experience enough cycles before the the glass is too abraded.
Another video on the drops with some more explanation and some super high speed video: https://www.youtube.com/watch?v=xe-f4gokRBs

As regards the pins, it seems worth considering the effect of vehicles accelerating and decelerating. This obviously involves the tires pushing on the tile surface, which will in turn be pushed into the pin or bolt. Steel being harder than glass, one would over time expect the bolt to come loose as it wore through the glass holding it in place. Having a road system where the pieces literally started sliding around whenever somebody hits the brakes sounds like a bad idea to me.

Now I'm not a material engineer, so it's entirely plausible to me that this only becomes an issue after so many years that some other part of the tile is extremely likely to have failed first, or only at intersections where vehicles do a lot of accelerating - the tires have to exert more force on the roadway when bringing the car up to speed or braking than when simply maintaining it at a set speed. In which case the solution is obviously to leave the intersections as untiled concrete or asphalt. Corners may also be an issue, but again I'm not sure how quickly this problem would arise.

More complicated fasteners could also help, to disperse the pressure through a larger area of the glass. But this makes the entire product more complicated again.

Max™
2014-06-21, 04:39 PM
Uh, I noticed a mention of crystalline structures, glass is specifically defined as an amorphous solid with a certain type of transition from a molten to solid state that occurs rather than crystalization. Generally a glass can be thought of as an extremely viscous liquid which exhibits certain solid-like properties or behavior.

Crystalline structures tend towards extreme toughness along certain planes in which the forces are transferred best among the component atoms and molecules.

Glasses tend towards extreme toughness due to the bonds between the atoms/molecules being particularly strong, and in many cases due to a tendency for cracks to lack readily available propagation routes.

With tempered glass the tension of the outer layers can be "tuned" to have a tendency for pressing chips and cracks back closed, rather than explosive propagation or deep crack formation.

The ability of the inner layers to remain undamaged due to this also hinders crack formation.

I don't think tempered glass was an arbitrary choice, though it is unfortunate that things like window glass or that used for cups tends to taint the perception of what glasses are really capable of. Ever seen torture tests with smartphone screens and whatnot? We can make those which withstand similar sorts of impacts as a danging tailpipe or cargo chain, and the thickness of the glass used is generally measured in millimeters or less. A chunk of tempered glass as thick as that being suggested for use on roads shouldn't be expected to explode the first or tenth or thousandth time a rock or piece of metal or whatever bounces off of it.

Karoht
2014-06-21, 04:56 PM
Little by little, the FAQ seems to be expanding and reorganizing. I wish they would put a date up (last updated on blah/blah/blah) or something. I'm just keeping track via the number of items.

Of note, one of the items in the FAQ states that in July they will begin constructing some of their new prototypes. They list several locations in addition to the parking lot. One of which is an airport tarmac. I'm guessing this is a small airport mostly because I don't know Idaho very well, but this still seems very promising.
Also, in another item on the FAQ they state that they will be working with a road testing company to test things like vibrations and other issues we've mentioned here. They'll be running an 18-wheeler 24/7/365 to gather data. Again, sounds promising.

2014-06-21, 06:59 PM
As regards the pins, it seems worth considering the effect of vehicles accelerating and decelerating. This obviously involves the tires pushing on the tile surface, which will in turn be pushed into the pin or bolt. Steel being harder than glass, one would over time expect the bolt to come loose as it wore through the glass holding it in place. Having a road system where the pieces literally started sliding around whenever somebody hits the brakes sounds like a bad idea to me.This would be an issue anywhere, not just where there is acceleration. By looking at the panels, it seems like all that force will be going through the pins and edges, which is not a good idea, but choice is a bit limited when the rest of the panel is covered in electronics.

And steel is not harder than glass most of the time.

Uh, I noticed a mention of crystalline structures, glass is specifically defined as an amorphous solid with a certain type of transition from a molten to solid state that occurs rather than crystalization. Generally a glass can be thought of as an extremely viscous liquid which exhibits certain solid-like properties or behavior.

Crystalline structures tend towards extreme toughness along certain planes in which the forces are transferred best among the component atoms and molecules.

Glasses tend towards extreme toughness due to the bonds between the atoms/molecules being particularly strong, and in many cases due to a tendency for cracks to lack readily available propagation routes.Eh no, glass is not a liquid. And it is not tough (order of magnitude less than many metals).

Little by little, the FAQ seems to be expanding and reorganizing. I wish they would put a date up (last updated on blah/blah/blah) or something. I'm just keeping track via the number of items.

Of note, one of the items in the FAQ states that in July they will begin constructing some of their new prototypes. They list several locations in addition to the parking lot. One of which is an airport tarmac. I'm guessing this is a small airport mostly because I don't know Idaho very well, but this still seems very promising.
Also, in another item on the FAQ they state that they will be working with a road testing company to test things like vibrations and other issues we've mentioned here. They'll be running an 18-wheeler 24/7/365 to gather data. Again, sounds promising.Noise, not vibration, and that's something they should have done already. Element testing should come before assembly testing. Good to see they are updating the FAQ though.

Max™
2014-06-21, 07:10 PM
Eh no, glass is not a liquid. And it is not tough (order of magnitude less than many metals).
Given I said in the post you quoted that glass "...is an amorphous solid... non-crystalline... can be thought of as an extremely viscous liquid...", rather than "is a liquid", not sure what you missed there. There isn't a phase transition between molten and glass states, there's just a point where certain materials can be cooled rapidly enough that they retain the amorphous arrangement of molecules/atoms like liquids possess, while lacking the low viscosity... which is probably why I used the word "extremely" there.

As for "tends towards extreme toughness...", that was me saying that as you move through the various types of glasses, the ones with the highest toughness and so forth achieve this in a different manner than things like Cubic Boron NItride or Aggregated Diamond Nanorods which are extremely hard in specific directions, less so in other directions.

NichG
2014-06-21, 07:25 PM
Given I said in the post you quoted that glass "...is an amorphous solid... non-crystalline... can be thought of as an extremely viscous liquid...", rather than "is a liquid", not sure what you missed there. There isn't a phase transition between molten and glass states, there's just a point where certain materials can be cooled rapidly enough that they retain the amorphous arrangement of molecules/atoms like liquids possess, while lacking the low viscosity... which is probably why I used the word "extremely" there.

The question of the glass transition is actually currently somewhat unsettled, its not as simple as 'no transition'. There's all sorts of stuff which tries to map the glass transition onto spin glasses and jammed mechanical systems.

Its just not the usual simple 1st order phase transition between liquid and solid.

warty goblin
2014-06-21, 07:57 PM
This would be an issue anywhere, not just where there is acceleration. By looking at the panels, it seems like all that force will be going through the pins and edges, which is not a good idea, but choice is a bit limited when the rest of the panel is covered in electronics.

It is an issue everywhere yes, but as more force is exerted on the tiles in places where vehicles are accelerating and stopping, it's more of an issue there. The consequences of failure are probably worse at an intersection as well; hitting the brakes and having the road disintegrate seems more likely to get somebody killed than the road failing when cruising down the highway.

And steel is not harder than glass most of the time..Even if the glass is harder, that just means it wears through the bolt instead of vice versa. Same problem; namely building a system with a few points of very dramatic failure that are also the primary stress points.

Karoht
2014-07-03, 10:48 PM
http://themindunleashed.org/2014/07/russian-physicists-launch-campaign-rebuild-teslas-wardenclyffe-tower-power-world.html

I'ma just leave this here.

No, I do not have any faith in this project actually being successful.

PallElendro
2014-07-06, 02:43 PM
I do enjoy the idea of planetary energy transmitters, but it doesn't have the secondary utilities quite like solar roadways do. There's no way to hold water or run Internets through one of those, at first glance.

NichG
2014-07-06, 03:14 PM
I'm somewhat curious how one can limit extracting that transmitted power to devices intended to extract that power (as opposed to, e.g., bridges or other conducting structures bolted into the earth, where it wouldn't be desirable to draw power). I'm guessing the towers have limited enough range that you basically just have to be careful about where you build them.

Karoht
2014-07-06, 04:21 PM
I posted it, mostly to say that I'm sure I have the same opinion of people who support this theory as some people have in this thread of me.
Though to be completely clear, I'm in support of research, and if the research fails then the idea fails. This applies to both Solar Roadways and Tesla's Towers.

huttj509
2014-07-07, 02:25 PM
So, my brother and I were discussing this, and started out firmly on different sides of "we NEED to be looking into this sort of thing." We realized something that was a definite influence on our perspectives.

Portland, Oregon roads are generally in much better condition than Indianapolis, IN.

OR: Asphalt is fine and easily maintainable.
IN: *falls off chair laughing* Apparently not.

More data's needed as to larger scale, pricing (at high production scales), and "actually running a semi over it 24/7" (which they're doing), but from the perspective of "our current roads generally suck...is there something better we could be doing" it's worth getting the needed data.

And personally, with the difficulty I have seeing the poorly maintained road lines at times, especially in parking lots...I like the LED possibilities.

Rockphed
2014-07-07, 05:16 PM
So, my brother and I were discussing this, and started out firmly on different sides of "we NEED to be looking into this sort of thing." We realized something that was a definite influence on our perspectives.

Portland, Oregon roads are generally in much better condition than Indianapolis, IN.

OR: Asphalt is fine and easily maintainable.
IN: *falls off chair laughing* Apparently not.

More data's needed as to larger scale, pricing (at high production scales), and "actually running a semi over it 24/7" (which they're doing), but from the perspective of "our current roads generally suck...is there something better we could be doing" it's worth getting the needed data.

And personally, with the difficulty I have seeing the poorly maintained road lines at times, especially in parking lots...I like the LED possibilities.

There are all sorts of things that could be done to make better roads. They just all cost more money and take more time than the roads that fall apart after five years. And elected officials never want to spend money on projects that won't bear fruit in their term.