Stories
Slash Boxes
Comments

SoylentNews is people

posted by LaminatorX on Sunday November 09 2014, @12:52AM   Printer-friendly
from the hot-wheels dept.

Several sites are running a story on the solar roadway installation in the Netherlands, including phys.org and IFLScience.

However over at EEV Blog is a thorough critical review by Dave Jones which runs through the numbers and finds it doesn't add up as a practical proposal. There's references to Dave's original review of an earlier proposal, for some background on the calculations.

From the associated forum posting:

Dave shows how to go about doing ballpark engineering feasibility calculations for such a project, calculates the expected payback period, and SPOILER, shows why Solar Roadways will never be a viable technology. This time using real measured data from the Netherlands cycleway prototype, and real measured solar insolation data for the Netherlands

Related Stories

Thieves Swipe a Portion of China's Solar Road 13 comments

Solar roads have plenty of potential problems, such as damage and snow, but theft? Apparently that's a concern, too. China's Qilu Evening News reported that thieves carved out a small (5.9in by 73in) portion of an experimental road in Jinan on January 2nd, a mere five days after its December 28th debut. While it's tempting to suggest this was an accident, officials said the missing segment was "neatly cut," and didn't appear to have come loose on its own.

The segment has since been repaired. An investigation is ongoing, but there aren't any identified culprits as of this writing.

Source: https://www.engadget.com/2018/01/07/thieves-take-portion-of-china-solar-road/

Previously: Solar Generating Roads
Solar Roadway not Quite so Practical
SolaRoad Cycle Path Electricity Yield Exceeds Expectations
World's First Solar Panel Road Opens in Normandy Village
Georgia Tests New Solar Road


Original Submission

This discussion has been archived. No new comments can be posted.
Display Options Threshold/Breakthrough

Mark All as Read

Mark All as Unread

The Fine Print: The following comments are owned by whoever posted them. We are not responsible for them in any way.
  • (Score: 0) by Anonymous Coward on Sunday November 09 2014, @01:08AM

    by Anonymous Coward on Sunday November 09 2014, @01:08AM (#114171)

    This project is so stupid to the point of incredulity. If anything, it would make way more sense to just make ceilings with the solar panels, instead of putting them on the floor where they are subject to traction. But even then, it will take a lot of time before it makes any economical sense.

    • (Score: 1) by Gertlex on Sunday November 09 2014, @04:45AM

      by Gertlex (3966) Subscriber Badge on Sunday November 09 2014, @04:45AM (#114193)

      It will never make economical sense...

      • (Score: 2) by mojo chan on Sunday November 09 2014, @09:21AM

        by mojo chan (266) on Sunday November 09 2014, @09:21AM (#114234)

        Actually it does. Dave screwed up on this one.

        His numbers are about right, in the ballpark at least. The problem is he doesn't compare the cost to what it would have cost to pave the cycle way with an ordinary tarmac surface. The solar system pays for about 60% of its cost over its lifetime, so if the original tarmac surface cost 40% as much it breaks even. It's actually better than break even because all the energy produced reduces CO2 emissions and pollution elsewhere, which have very real cost savings.

        --
        const int one = 65536; (Silvermoon, Texture.cs)
        • (Score: 2) by tonyPick on Sunday November 09 2014, @10:46AM

          by tonyPick (1237) on Sunday November 09 2014, @10:46AM (#114240) Homepage Journal

          The problem is he doesn't compare the cost to what it would have cost to pave the cycle way with an ordinary tarmac surface.

          I thought he covered this in his comparison of construction costs (skip to 1280 seconds). Specifically the source data is at: http://www.worldbank.org/transport/roads/c&m_docs/kmcosts.pdf. [worldbank.org] (Note that the Rehab cost to install the road and maintain the panels is considerably higher than standard road maintenance costs).

          The associated forum talks a the specific numbers around here: http://www.eevblog.com/forum/blog/eevblog-681-more-solar-roadways-bullshit!/msg545930/#msg545930. [eevblog.com]

          And even in the case where you're repaving a road it's still just better (way cheaper, far more power) to stick the panels on a nearby roof or raised/angled surface, rather than the floor, as long as you have roof space available (and we still have lots of that). Now when you run out of roof space _and_ this is considerably cheaper then maybe, but I don't think we're even close to that yet.

          • (Score: 2) by mojo chan on Sunday November 09 2014, @01:45PM

            by mojo chan (266) on Sunday November 09 2014, @01:45PM (#114263)

            Those stats are for roads, no cycle ways.

            --
            const int one = 65536; (Silvermoon, Texture.cs)
            • (Score: 2) by tonyPick on Sunday November 09 2014, @02:29PM

              by tonyPick (1237) on Sunday November 09 2014, @02:29PM (#114269) Homepage Journal

              Yep - but I can't find any evidence that different cycle way costs will significantly change the ballpark - at least to within an order of magnitude:

              i.e. from: http://www.aph.gov.au/parliamentary_business/committees/house_of_representatives_committees?url=primind/rdinq/sub54-e.pdf [aph.gov.au]

              A typical off-road cycleway costs around $100k per kilometre to construct.

              That's lower than the initial estimates based on the road figures (original 172K euro/km, $100k (Australian) is about 69k euros), so the roadbuild cost per m^2 drops... by 13 euros to 9 euros, and the total build cost from 292 to 279.

              We're still nowhere near the 150 euro mark we need to be to be around a rooftop system (at which point we start to worry about maintenance), and still at near enough to hit the "twice as much for a quarter of the output" result given the number of other assumptions baked in.

              • (Score: 2) by mojo chan on Sunday November 09 2014, @02:58PM

                by mojo chan (266) on Sunday November 09 2014, @02:58PM (#114275)

                Err... 69,000 euros per 1000 metres is 69 euros per metre. I don't know where you got 9 from.... That's actually a rather low estimate, at least for Europe: http://transportretort.wordpress.com/2011/02/09/how-much-would-cycle-paths-cost/ [wordpress.com]

                By the time you have added maintenance on top to match Dave's figures a solar cycle path makes sense.

                --
                const int one = 65536; (Silvermoon, Texture.cs)
                • (Score: 0) by Anonymous Coward on Sunday November 09 2014, @05:14PM

                  by Anonymous Coward on Sunday November 09 2014, @05:14PM (#114291)

                  69,000 euros per 1000 metres is 69 euros per metre.

                  You don't care about per metre - you care about per square metre. So the "9" figure is actually "about 40%" of the construction cost for Rehabilitation work, which rather generously assumes that the equivalent width holds to TFA figures (which are very generous to start with). In practice the cycle lane won't be as wide, and your cost per square meter is actually pretty high, which actually makes the numbers for the cycle path lightway even worse than those for the road case.

                  By the time you have added maintenance on top to match Dave's figures

                  What do you think the MTBF per solar cell is? For the rooftop system the MTBF is high, and the maintenance cost very very low.

                  Look, you're competing with a total lifetime cost (from TFA) of 150 Euros over about 15 years by slapping a panel install on a roof next to the path. Just fitting the lightway has cost you twice that, your maintenance costs will be higher and can only add to that figure, and you're recovering a quarter of the electricity to offset the initial costs. Practically they need to demonstrate very low maintenance and hit an install cost of less 40 euros per square meter for the baseline install on the path to even get close to rooftop. Not. Going. To. Happen.

                  Look - if you want to publish a TCO calculation with maintenance offsets over failure rates versus energy harvest then I could be persuaded, but so far by the numbers you're not even close.

  • (Score: 0) by Anonymous Coward on Sunday November 09 2014, @01:19AM

    by Anonymous Coward on Sunday November 09 2014, @01:19AM (#114172)

    I mean, who doesn't love the idea of solar roads, especially since everyone's pushing for smarter roads for autonomous vehicles anyways.

    But I can't say I'm surprised that they are expensive. It's kind of a ridiculous idea to generate low voltage DC so far from where it would be used; obviously you have to step up the voltage and transmit it long distances. Then there's wear. I mean, where I live (Indiana), there's potholes in every damned road, and that's asphalt. You have to hold the road to a much higher standard if you're going to generate electricity out of it, as even scratches would probably block some light. This thing went viral because it was pretty, and used something that's currently wasted space. But... I think it's pretty ignorant to expect to make money from it.

    Most of the roads I drive on would look unimaginably sad if they were solar roads; they would be littered with broken panels. I would also think that these panels would probably be more of a safety hazard than just a pothole; unless the high voltage lines were separate.

    • (Score: 2) by edIII on Sunday November 09 2014, @01:32AM

      by edIII (791) Subscriber Badge on Sunday November 09 2014, @01:32AM (#114174)

      I hardly think it's fair to compare NORWAY to say... SOUTHERN CALIFORNIA as I know the amount of sunlight hitting Norway every year is nowhere near the amount of sunlight hitting a house in LA or Vegas.

      Yes, they have to be engineered very well to remain optimal until replaced. Yes, this may result in a higher cost assuming the technological breakthru wasn't in producing them efficiently.

      This may prove it's an unwise technology for Norway. I mean, who would have thought, that such a country being located where it is, that solar might not be the best way to go. I dunno. Maybe.

      To say it's never going to be a viable technology when the efficiency of it is highly dependent on variable factors, most noticeably, how much sunlight your local environment receives on average.

      It doesn't impress me to pull out all the stops and show that hydroelectric would be a moronic solution in a seriously dry place, like a certain desert in Peru. On the other hand, I'm betting a solar road may perform better out there.

      • (Score: 0) by Anonymous Coward on Sunday November 09 2014, @01:36AM

        by Anonymous Coward on Sunday November 09 2014, @01:36AM (#114175)

        The Netherlands are not Norway. That is all.

        • (Score: 0) by Anonymous Coward on Sunday November 09 2014, @01:44AM

          by Anonymous Coward on Sunday November 09 2014, @01:44AM (#114176)

          The Netherlands is also not plural. That is all.

          • (Score: 0) by Anonymous Coward on Sunday November 09 2014, @03:14AM

            by Anonymous Coward on Sunday November 09 2014, @03:14AM (#114186)

            The Netherland are also not plurals. That are all.

          • (Score: 1, Informative) by Anonymous Coward on Sunday November 09 2014, @04:38AM

            by Anonymous Coward on Sunday November 09 2014, @04:38AM (#114191)

            http://dictionary.reference.com/browse/Netherlands [reference.com]

            the, (used with a singular or plural verb) a kingdom in W Europe, bordering on the North Sea, Germany, and Belgium. 13,433 sq. mi. (34,790 sq. km). Capitals: Amsterdam and The Hague.

            So can be singular or plural.

      • (Score: 2) by urza9814 on Monday November 10 2014, @06:24PM

        by urza9814 (3954) Subscriber Badge on Monday November 10 2014, @06:24PM (#114576) Journal

        Common sense alone says solar roadways will never make much sense. They may someday get cheap enough that we can ignore the extra cost, but even then generating on the roads is kinda moronic unless you're trying to power road lights (which is a good idea, including digital lane markings if those work out) or if you're in the middle of NYC and need to do everything imaginable to raise the density of power generation.

        But in general? Yeah, this is dumb. The solar panels are more efficient sitting on your roof than they are under thick glass under a roadway. So already it's better to build the solar roads without solar panels and put the panels on rooftops. But we don't build roads out of glass for very good reasons. It's fragile and it's expensive. So stick the solar panels on the roof and build the roads out of something cheaper and easier to maintain. Like asphalt.

        Of course every technology has its niche, and it's good to explore this stuff to figure out what that is, and just to keep the technology moving forward. But right now the possible use-cases for solar roadway is closer to "Tech demo at the shopping mall of tomorrow!" rather than "every roadway in America!"

        There *is* one other way these could take off though, and that is if they're eventually able to replace other forms of road maintenance. If we get it cheap enough (These aren't even *close*, you'd need it to be as cheap as a regular road) then added features could tip the scales. Heated roads means no plows, no salt, no plow drivers. But that would use more power than the panels can generate, maybe we can bury some E-cat devices alongside it ;) Gotta make sure the heating is cheaper than running a plow. Could also maybe use it for emergency remote rest-stop charging stations for electric cars. Still probably cheaper to just put panels on the roof though. Maybe if the road is going through a national park. Dynamically changing lane markings could be a boon too -- for major cities like New York. They're not going to do a damn thing for Johnstown, PA. Maybe they could integrate with smart cars to extend the sensing capability, and pay off in reduced crash fatalities? That's all a long way off though; all dependent on the base technology of the glass and solar panels getting cheap enough.

        This is basically the point Dave was making on EEVBlog. If people are hyping the solar roadways as an immediate solution that should be rolled out nation-wide, they're clearly full of it. That's a terrible idea. That's also why he was a lot harsher against the "Solar freakin' Roadways" video than this concept -- that one was selling a completely impossible vision , where this one is more along the lines of just running a test and seeing what happens. If you watch the video he's actually very positive about this project, very supportive of the engineers behind them, he clearly says they're doing everything right. And when you run the math, using their figures and test results, it's just not economical.

        • (Score: 2) by edIII on Monday November 10 2014, @08:53PM

          by edIII (791) Subscriber Badge on Monday November 10 2014, @08:53PM (#114620)

          You have some good points, it's just that when I hear the majority of the data supporting his position is derived from Norway that I'm a bit incredulous already.

          There are entire countries that *aren't* Norway. For Dave to be attempting to bring the science, I think he needed to be more impartial than that, and nothing he has supports the concept of "never". I didn't read everything; He might be assuming 100% efficiency like photosynthesis directly on the roads.

          That being said, when I hear solar roadways I think of the Solar Roadways [solarroadways.com] project itself.

          Many of your concerns are directly answered, and your intuition is entirely correct on the numbers also making sense by gained efficiency in maintenance and the addition of other features and services.

          According to them, Solar Roadways covering the US would provide three times the amount of power needed each year (based on reported consumption).

          With that in mind, I find Dave's blog to be entirely suspect if it's based on peak daylight hour data from Norway, and I'm fairly positive we aren't talking about the same technology as Solar Roadways is in its R&D phase.

          Unless these Solar Roadways people are just full of crap and no scientists agree with their assumptions. In that case, they are great bullshit artists. Their website has actual data and lists references contradicting Dave.

          Dave has a whiteboard and a video. Not saying he might not have some points, but that he should come back when he is using data for every country and is making these assessments on a per-country basis. The data he wants is not inaccessible either, and has already been collected by other scientists.

          Maybe Dave should step back and redo the analysis?

          • (Score: 2) by urza9814 on Wednesday November 12 2014, @01:31PM

            by urza9814 (3954) Subscriber Badge on Wednesday November 12 2014, @01:31PM (#115165) Journal

            There are entire countries that *aren't* Norway. For Dave to be attempting to bring the science, I think he needed to be more impartial than that, and nothing he has supports the concept of "never". I didn't read everything; He might be assuming 100% efficiency like photosynthesis directly on the roads.

            Dave starts the comparison by pulling real numbers from his own rooftop solar power system. In Australia. But when you compare to the other costs of this system, it really doesn't make much difference. They could recover 10 times more energy from the solar cells, it'd still be a waste of money. The point is that the money you get back from generating the solar power is a good order of magnitude less than the money it costs to build and maintain the roadway. Furthermore, as I mentioned in my previous post, if you can put the solar cells in the roadway you can just as easily put them on nearby rooftops, where they will have a greater efficiency -- they're not under thick glass, they're not under road dirt and traffic, they're at a better angle, etc. So again, it only makes sense if you're building it somewhere remote (where it might still be cheaper than getting power there any other way) or if you're already building the roads out of glass modules with electronic systems, in which case the cost of adding a solar panel might be worthwhile.

            According to them, Solar Roadways covering the US would provide three times the amount of power needed each year (based on reported consumption).

            So would a relatively small number of nuclear power plants. OF COURSE we can get enough power this way, the question is: At what cost?

            With that in mind, I find Dave's blog to be entirely suspect if it's based on peak daylight hour data from Norway, and I'm fairly positive we aren't talking about the same technology as Solar Roadways is in its R&D phase.

            Why? Dave's numbers actually confirm the plan by the solar bike path designers to power 3 homes with a 100m segment of this. In fact, his initial estimate was *better* than their actual, demonstrated test results! Again, it's not that it doesn't produce enough power, it's that the power it produces is too expensive. Is it cheaper than building nuclear plants? Is it cheaper than putting the solar panels on your roof? Hell, when you look at the concept of digging up and replacing every road in America, it *might* even be cheaper and faster to throw that money into Fusion!

            Unless these Solar Roadways people are just full of crap and no scientists agree with their assumptions. In that case, they are great bullshit artists. Their website has actual data and lists references contradicting Dave.

            Dave has a whiteboard and a video. Not saying he might not have some points, but that he should come back when he is using data for every country and is making these assessments on a per-country basis. The data he wants is not inaccessible either, and has already been collected by other scientists.

            Dave uses *their own data* for his calculations. And the math from there is not very complicated and does not really affect the outcome much (ie, he assumes a rather low 30% losses, but even 0% losses wouldn't make it feasible). Did you watch his video?

            • (Score: 2) by edIII on Thursday November 13 2014, @07:46AM

              by edIII (791) Subscriber Badge on Thursday November 13 2014, @07:46AM (#115462)

              Why? Dave's numbers actually confirm the plan by the solar bike path designers to power 3 homes with a 100m segment of this. In fact, his initial estimate was *better* than their actual, demonstrated test results! Again, it's not that it doesn't produce enough power, it's that the power it produces is too expensive. Is it cheaper than building nuclear plants? Is it cheaper than putting the solar panels on your roof? Hell, when you look at the concept of digging up and replacing every road in America, it *might* even be cheaper and faster to throw that money into Fusion!

              I didn't watch the video because the TFS implied that he used actual production data for his analysis. There is *no* production data for Solar Roadways anywhere in the world, much less Norway (I can't see at all how Norway's data is relevant). This is why I'm not sure we are talking about the same thing when you say "bike path" designers. Solar Roadways is not a bike path. Bike paths don't get rated for 250,000 pounds.

              Now I see where you are coming from though. At first I thought Dave's objections were that it couldn't product the amount of energy required, when I knew that it could. Your objection is that Solar Roadways can't possible have ROI. That's patently false, and I don't see how Dave (or anybody) could even determine that yet either. Even the Solar Roadways people don't have numbers on maintenance savings and economic impacts of the panels other features across the board.

              Solar Roadways directly addresses your other concerns. The fact is, we really *do* need to dig up and replace all the roads in America. We've spent less than half of what other developed nations have spent on infrastructure and it shows. Quite a few people have died already in bridge failures. It's inevitable. So I find it pointless to talk about the costs of digging them up when that is non-negotiable. Absolutely. Non. Negotiable. There are too many newer technologies, and asphalt doesn't cut it. America needs new interstates, bridges, and transportation technologies badly.

              So if we *have* to replace the roads and bridges, we might as well get the bang for the buck. What I find amazing, but apparently true, is that if a panel costs *less* than 10k, it *beats* asphalt. We get to put them at less of a cost than asphalt.

              We also get a LOT more than power generation being added to ROI. Each panel is actually extremely tough making any concerns over long term maintenance practically baseless. They beat out asphalt for strength and durability (impervious to potholes), and can keep up with the German Autobahns which have enough concrete to allow jumbo jets to land on them. Maintenance can be wholly automated with machines picking out these modular panels and putting in new ones. Since it's automated, that also implies to me less impact on traffic leading towards savings for commuters. No need for expensive machinery carted on site to cut into the ground for maintenance either. Your concern about skid marks is something they acknowledge and will wait for further testing. That being said, the rubber from car tires doesn't stick to the surface of the panel. It can be wiped off with a hand, or rain.

              One cannot understate the value of good cable management and these panels (along with the installation) include abilities to run all kinds of conduit and drainage. If we do it at the same time, we *always* have a place to lay down fiber optical with it's own built in redundant power. This means micro cell towers, wifi, wimax, etc. support. No longer do you need to spend tens of thousands with ISPs to make cable runs in the street. They're modular. Pull them out, stack them to side, and put a tarp on them. This alone saves such serious amounts of money every day in the US, I'm betting that it alone takes out a significant chunk of Dave's negative ROI.

              If we replace our interstates and our roads with it, I believe it's reasonable to also assume that we will realize savings with a platform that allows for cheaper design and implementation of other supporting technologies. After all, you get both power and communications at any point along the road. That's wide open for all kinds of ROI for the state in the forms of paid easements and last-mile-ISPs reselling access and bandwidth from upstream providers. At the same time we replace the roads, we are also replacing the conduit for literally all of our other communications.

              All of these factors need to be included. Dave is saying that's it off by an order of magnitude, but Solar Roadways *only* needs to beat asphalt for price and overall performance too. Which they have, while also producing distributed power. These facts seem mutually exclusive. I can keep imagining all sorts of projects for traffic control and advanced services that have benefits in other areas of society making their subsidization something that makes sense.

              In other words, I don't think Dave could even calculate the true ROI for it yet. I'm not going to write Solar Roadways off completely. It's a worthy enough idea to be tested at least city wide someplace in the Southwest.

              • (Score: 2) by urza9814 on Thursday November 13 2014, @01:50PM

                by urza9814 (3954) Subscriber Badge on Thursday November 13 2014, @01:50PM (#115537) Journal

                Dave did a separate video on that project which reached pretty much the same conclusions. Yes, it's possible, but the ROI is going to be shit.

                Some of the problems are pretty basic, and even the team developing these admits it's a problem. For example, they propose heating the panels to clear snow. The specs on their own website say the heaters draw 72W, and the panels produce 36W. In other words, these panels still require external grid power if they're going to see nation-wide deployment. Or some truly *MASSIVE* storage system (Think 2.4GW is a lot? Try storing 24 THOUSAND GWh). Same goes for powering lights and sensors at night -- read the solar roadways website, they give numerous reasons these will *require* external grid power. From...what? Coal? Gas? Nuclear?

                And again, putting a solar panel under thick glass, flat on the ground, under dirt and dust and road traffic will never be more efficient than putting that same panel on a rooftop. We've gotta rebuild roofs periodically just like we rebuild roads. Design a solar shingle instead of a solar roadway, you'll get a higher ROI.

                There's also the fact that they promised to have data regarding the costs of these panels posted several months ago. Site still says they "will be doing so in July, 2014." They DO actually have some test results regarding power generation, but those mean nothing if you don't have a total system cost. They got over $2 million from that Indiegogo campaign, you'd think they could take five minutes to update the website in the months since...

                I mean it certainly is a cool project, and we're probably heading there someday. I just think it's more likely to be plugged into fusion plants and consuming power rather than providing power to the entire country. They've put so many sensors and indicators into it that it can't even power *itself*!

  • (Score: 0) by Anonymous Coward on Sunday November 09 2014, @05:18AM

    by Anonymous Coward on Sunday November 09 2014, @05:18AM (#114204)

    ...a video? For a technical article? My life is too short.

    • (Score: 0) by Anonymous Coward on Sunday November 09 2014, @12:55PM

      by Anonymous Coward on Sunday November 09 2014, @12:55PM (#114257)

      ...and my life is even shorter, having watched most of it, waiting for him to get to the effing point.

  • (Score: 1) by klondike0 on Sunday November 09 2014, @04:19PM

    by klondike0 (1511) on Sunday November 09 2014, @04:19PM (#114281)

    I don't mind someone developing these concepts, on private money in small scales until it is actually proven to work and make economic sense.

    Solar Roadways (similar group in the US, not affiliated with SolaRoad from TFA) has updated its FAQ to address more of these types of concerns since the last time I looked when this came up a few months back. http://www.solarroadways.com/faq.shtml [solarroadways.com]

    I've got my doubts as to whether this concept will ever pencil out but I'm curious as to how the private party installations turn out that they claim to be installing come spring. I would protest my tax dollars (beyond grants) going to this unless there's some better numbers for the return at 48 degrees latitude, and they prove that studded tires don't eat that surface for lunch.

    As SR does not yet acknowledge that some road orientations and widths would be better suited to solar production than others, they seem to bank on the idea that this will become ubiquitous rather than be a good way to create renewable energy projects --> mass production, standardization and interoperability will allow the system to be installed everywhere overcome bad spots over the aggregate.

    SR also claims to create a true distributed grid. So beyond all the technical & monetary challenges they have and haven't addressed, there are some significant political ones as well.

  • (Score: 0) by Anonymous Coward on Tuesday November 11 2014, @07:32PM

    by Anonymous Coward on Tuesday November 11 2014, @07:32PM (#114952)

    Okay folks, due dilligence. I am not a physicist, or even particularly good at math however i would urge any/all of you to head on over to them thar youtubes and hunt out Thunderf00t's vlogs about solar roadways. He talks about the proposals clearly and understandably enough that even i was able follow what he was saying and to trace his citations and do the math myself (actually with the help of a good friend).

    Granted he is talking about the system proposed for the US and the daylight figures will be different but i think the most important point he makes is how well this surface compares to asphalt with regards to friction.

    Asphalt provides a durable, porous, and highly frictive surface which allows water to drain away and provide enough grip to keep your vehicle on the surface as opposed to spinning wildly off into a ditch.

    Given the comparative 'softness' of glass as compared to asphalt, any surface roughening applied to the glass in order to increse its frictive properties, will be quickly smoothed out by the continued wear of passing tyres, making light transmition through the glass less efficient, increasing the possibility of loss of friction between surface and tyre, not to mention what it might be like to drive on a glass surface when its wet.