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Study suggests that fresh asphalt is a significant source of air pollution
- nickff 6y agoHere is the Yale press release: https://news.yale.edu/2020/09/02/asphalt-adds-air-pollution-especially-hot-sunny-days https://news.yale.edu/2020/09/02/asphalt-adds-air-pollution-... And the paper: https://advances.sciencemag.org/content/6/36/eabb9785 https://advances.sciencemag.org/content/6/36/eabb9785 I'd also like to point out that road wear is approximately proportional to the cube (^3) of the weight per axle on a vehicle, so cars are probably responsible for a minority of this pollution. *edit: some are pointing out that the relevant road wear is proportional to the 4th power of vehicle weight, see the comments below for details.
- gwbas1c 6y ago> I'd also like to point out that road wear is approximately proportional to the cube (^3) of the weight per axle on a vehicle, so cars are probably responsible for a minority of this pollution. Could you clarify that a bit? Do you mean that the friction of the tires on the road releases nasty emissions?
- pathseeker 6y agoNo, heavy trucks wear out the road significantly more than cars and result in asphalt having to be replaced more frequently. This is another case where the gas tax isn't really adequate for funding road issues due to the disproportional increase in costs to the increase in fuel usage by trucks. All of the light vehicle drivers subsidize the heavy trucks in all mileage/fuel based tax schemes.
- Valgrim 6y agoFor this reason, in northern latitudes, weight limits for trucks drop significantly during the spring season. Shipping water bottles, ice salt and windshield washer in stores becomes a real pain in the ass.
- shajznnckfke 6y agoFor what it’s worth, you can buy windshield washer concentrate online. In months where the temperature gets cold, though, you want the alcohol based stuff that won’t freeze and burst a line.
- melling 6y agoSounds like we need to expand our rail capacity. Our current rail freight capacity is near 100%.
- gruez 6y agoWhy not tax each mode of transportation proportionately to their true cost, and let the market decide?
- melling 6y agoHow do you price in the fact that heavy trucks destroy the road faster, causing them to be replaced more often, causing more pollution? In other words, how do you price in the pollution? And do you really want to?
- Taek 6y agoYes, you really do want to. It would be lovely if we could charge proportional to the externalities. As for how... beats me. Best we can do is rough approximation, and accept that we will continually find out we were wrong and have to adjust the cost structure.
- epistasis 6y agoWe could get the approximations quite wrong and still get massive economic improvements from where we currently are! However the challenge isn't the approximations, but the political difficulties. Even taxing based on mileage would cause an uproar. And taxing large pickups proportional to their economic toll on infrastructure would probably start a violent revolution.
- lostapathy 6y agoLarge pickups aren’t an appreciable part of the problem here - 18 wheelers are.
- mirkules 6y agoThe way you frame this makes it seem like a road tax is in our future. That, in turn, makes me more skeptical about this study, the funds for which were granted by the EPA. I’m not really insinuating the EPA is after your tax dollars, but the fact that a government agency funds a study that can have tax implications should at least raise an eyebrow. I don‘t know how common this is. The problem I have with this is that the gas tax was [Edit: this is apparently not true, as was pointed out below] created because exhaust fumes were damaging the environment and reducing air quality - and I agree with that. But now that we have made significant strides towards reducing emissions - both in the way of more efficient vehicles and battery-operated vehicles - causing a decrease in gas tax dollars flowing in, suddenly we have another source of emissions which would require another tax. I can’t help but feel that at least on some level this will be a money grab - even if the underlying study is confirmed long-term.
- CameronNemo 6y ago>the gas tax was created because exhaust fumes were damaging the environment and reducing air quality Do you have a source for this? Everything I have read states that gas taxes were first enacted to finance road construction (thereby leading to more exhaust fumes), and gas taxes in place today often dedicate the majority if not all of their funds to road building. https://en.wikipedia.org/wiki/Fuel_taxes_in_the_United_States https://en.wikipedia.org/wiki/Fuel_taxes_in_the_United_State...
- mirkules 6y agoActually, I don’t have a source, it was just my assumption, so you’re probably right. But seeing the downvotes roll in, I should have known better than to question the financial motivation for an environmental study on HN.
- throwaway0a5e 6y agoPairing those questions with skepticism of government certainly didn't help.
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- cameldrv 6y agoYou could get a decent approximation of the right tax by taxing diesel more. Especially after dieselgate, there are hardly any light vehicles that use it.
- adwww 6y agoExcept in Europe, where Diesel peaked at almost 50% of all vehicles sold - pre dieselgate.
- lostapathy 6y agoThat same hammer would also hamper innovation in new light diesel vehicles. All three auto makers now make diesel half ton trucks and Jeep is expanding it into more vehicles. We should encourage that.
- deleted 6y ago[deleted]
- nickff 6y agoA few things came to mind for me: - Many of these emissions are described as being from paving, so more frequent repaving caused by increased wear would aggravate the issue. - These issues seem to be related to temperature, and I suspect that the increased wear by heavier vehicles is largely caused by increased friction (which would increase temperature-related emissions). - Cracks and potholes expose more asphalt, and are largely caused by the heavier vehicles.
- zip1234 6y agoTires wearing out is indeed a source of pollution though. That material wears off onto the roads.
- wolfram74 6y agoI thought it was roughly to the 4th power of the vehicle? At least that's what this chart [1] suggests and I've heard in a few engineering podcasts [1] https://streets.mn/2016/07/07/chart-of-the-day-vehicle-weight-vs-road-damage-levels/ https://streets.mn/2016/07/07/chart-of-the-day-vehicle-weigh...
- marcosdumay 6y agoIt's a complicated function that behaves like different powers at different depths. But superficial wear (this study) should have a higher power than deep wear (your link). Civil engineers normally used the 3rd power for deep wear... Maybe the people on your link got a table from something different than what they though it was.
- LeifCarrotson 6y agoVehicle weight is not directly proportional to axle count - a 9 axle semi with trailer can weigh 80,000 lbs or 9000 lbs/axle, a 2-axle car weighs 3500 or 1750 lbs/axle. Alternatively, multiplying axle count by 4.5 increases vehicle weight by 25x - so the two can both be true at the same time, the power just changes whether you use vehicle weight or axle load.
- yread 6y agoWhat effect does tire width have? Very narrow (<165mm) tires vs dual tires of trucks for example. Smaller area of friction versus lower pressure
- serf 6y ago>What effect does tire width have? probably quite an effect, but reducing damage via width will also decrease vehicle efficiency and increase rolling resistance, so the gains at the road may be lost in an overall loss of efficiency at the vehicle, not to mention manufacturing and materials cost, when finagling the tire-width variable. I don't have any numbers, though.
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- throwaway0a5e 6y ago>I'd also like to point out that road wear is approximately proportional to the cube (^3) of the weight per axle on a vehicle, so cars are probably responsible for a minority of this pollution. This is a very, very, large over-simplification and contains some large assumptions about road material, the road base, the ground pressure of the axles and the local climate (which affects the road construction techniques). This is a rule of thumb to help city planners come up with a ballpark number that's within an order of magnitude. Don't present it as though it's a hard and fast rule.
- namdnay 6y agoHence the caveat “approximately proportional”
- enkid 6y agoEven if it's a ballpark figure, the GP's statement would still be correct, no?
- nafey 6y agoAs someone who had to study civil engineering as an undergrad a lot of the formula are empirical. 3rd power law might not coorelate with degradation of some road some road while others might exhibit 5th power law. However if I recall correctly the correlation between road wear and axle load was ^4.
- deleted 6y ago[deleted]
- crazygringo 6y agoThe press release doesn't say anything at all about road wear, pressure or friction, so cars vs. trucks has nothing to do with it. It appears to be entirely about the role of asphalt releasing compounds when exposed to sunlight and high temperatures. So even if there was zero traffic on the roads, asphalt would still be producing the described pollution on a bright summer day.
- Retric 6y agoThe greatest amount of semivolatile organic compounds escaped when the pavement was heated to 140°C Asphalt is usually delivered at 275-300f (135-150°C) and needs to be over 185f (85°C) when applied. So, a warm summer day is cold by comparison. Resurfacing is also heavily impacted by use.
- apendleton 6y agoIt does look like emissions are highest when the asphalt is fresh, even though they persist after that, so to the extent that more wear results in more frequent replacement (and so, more time during which the asphalt is fresh), there's probably some connection there?
- jemfinch 6y agoRoad wear is what makes communities repave roads, so cars vs. trucks has quite a bit to do with it.
- abdullahkhalids 6y agoYes, each car does little damage compared to a truck or bus. But how do the numbers compare for the total number of cars vs HTV right now? Is the ratio of cars:HTV better or worse than 1:3?
- lrem 6y agoUh, why 1:3? European cars are generally about 4x lighter than European TIRs. If the proportions are similar in the US, you should be asking about 1:64 if the cube is right, or 1:256 if the fourth power is. Edit: also, there's the duration of use per day. Typically about 1h for cars and 10h for trucks here, so you should be asking about 1:2560.
- NeutronStar 6y agoThere's what, 10M truck driver in the US? It's pretty safe to say trucks are at least 10x worst than cars on the road.
- tlbsofware 6y agoCould this problem be temporarily mediated by expanding the width of tires to increase the surface area and disperse the weight?
- ffpip 6y agoThe roads near my house - https://economictimes.indiatimes.com/videodash.cms?autostart=1&msid=70948040&rlvideo=1052732854&fallBackMute=true&skipad=false https://economictimes.indiatimes.com/videodash.cms?autostart...
- yboris 6y agoDo not click: 30 second unskippable ad. Link to the same footage on YouTube directly: https://www.youtube.com/watch?v=5NDDncs47ro https://www.youtube.com/watch?v=5NDDncs47ro
- athenot 6y agoThis one had a 15-second unskippable ad.
- jagannathtech 6y agolol
- ffpip 6y agoSorry. I use uBlock Origin. I had linked to the video frame instead of the article. Clouldn't get direct video link. Doesnt your link have ads too? Youtube?
- totetsu 6y agoAlways gets me.. send people a link, with no idea there was ads. The worst was when i sent someone a link to an old tv show, and the page was full or porn ads unbeknownst to me.
- newyankee 6y agoIt definitely seems rail might be lower polluting in this respect.
- mmhsieh 6y agoi wonder about the brake dust in not only cars but trains as well. maybe where trains don't decelerate much there is less pollution?
- liability 6y agoI'm not sure, but I think modern trains usually use electrical braking instead of friction.
- deleted 6y ago[deleted]
- rootusrootus 6y agoPerhaps an all-electric train could, do they just feed it back into the grid? Freight trains mostly use air brakes, which are friction.
- liability 6y agoA diesel-electric freight train locomotive can use dynamic braking by dumping the electrical energy into a bank of resistors (known as rheostatic braking, opposed to regenerative braking, but collectively called dynamic braking.) However apparently this form of braking is only a small portion of braking that freight trains do since only driven axels can participate in it and most freight cars are unpowered. I didn't consider that.
- detaro 6y agoAs far as I know only rarely, and even those trains do have mechanical brakes too. Modern electric locomotives can do engine braking, but brake power needs to be applied everywhere on the train, so most of the train brakes mechanically. (And if you want to engine brake, the energy still needs to go somewhere - so you have additional complexity of feeding it back into the grid or you are limited by how much energy you can dump to heat) Only (mostly high-speed) passenger trains with driven wheels everywhere can brake well only electrically for non-emergencies. Some also have additional eddy-current brakes that interact with the rails. For the German high-speed trains they try to design the speed profiles so that they have to waste as little energy as possible by using the motors as generators and feeding it back to the grid. But they still have and use eddy-current and mechanical brakes too. (You can tell the difference if they are delayed: they brake later and more aggressively to make up time. And a full-on emergency stop is loud and smelly.)
- whalesalad 6y agoAn underlooked quality of Asphalt is that it is the most recycled material on earth. Asphalt can be, and generally is, made of old asphalt.
- save_ferris 6y agoThat’s interesting. I wonder what goes into reusing old asphalt (i.e. what new chemicals need to be added/removed in order to make old asphalt pliable or whatever the term is to lay it again).
- Shivetya 6y agoIt isn't just the asphalt that is recycled but many other products are recycled into it as well, shingles, tires, and even glass, can all end up into it. what they take off the road can be ground and used on site for a layer but mostly its carted off and ground to the same size as the original aggregate and combined into new. since the binding material is still present it reduces the need for more oil byproducts
- azinman2 6y agoSuper interesting. I always assumed it was a gigantic use of oil globally. Sounds like it doesn’t have to be. But most of those items are oil originated. At what point can we make asphalt without any new oil?
- iscrewyou 6y agoThe term describing this is: RAP (Recycled Asphalt Pavement). https://www.fhwa.dot.gov/publications/research/infrastructure/pavements/11021/11021.pdf https://www.fhwa.dot.gov/publications/research/infrastructur...
- jiofih 6y agoThat sounds great for the environment - let’s grind and hide this pile of trash for a few decades, what could go wrong.
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- EarthIsHome 6y agoI'll preface by saying I'm not trying to downplay cars or the roads.. but doesn't almost everything we consume make pollution in a non-negligible quantity? e.g. when cars are manufactured, the plastics we use, livestock, etc. It's a multifaceted problem that won't be fixed by changing one thing like cars or the roads.
- xnx 6y agoAll money spent causes pollution if you trace it back far enough. As a first approximation, environmental impact is directly proportional to cost.
- ironmagma 6y agoThat’s an oversimplification, if nothing else because you can spend money to save money. Likewise you can make a monetary expenditure to prevent other more environmentally costly expenditures.
- tonyedgecombe 6y agoIt's not a bad approximation. More flights, bigger houses, bigger cars, more toys, faster computers. They all cost more and all have a bigger environmental impact. There are a few things where spending will decrease your emissions, loft insulation, possibly replacing your petrol car with an EV, definitely replacing it with an e-bike. Even if there are savings made what do people do with their reduced energy costs? Mostly buy more products/services.
- ironmagma 6y agoTo some extent yes, but that is different from the claim, which is about "all money." But also, you're neglecting things like cheaper parts tending to be worse for the environment. Comparatively expensive wood, for instance, would likely cause fewer problems than cheaper plastics. Plus, that's true by virtue of the cheaper parts breaking sooner and needing to be replaced. It's certainly not a universal that luxury goods are eco-friendly, but it is true that eco-friendliness is a factor that requires a premium to be paid for it.
- csours 6y agoPareto principle in action - remove the bulk of tailpipe particulate emissions, and the previously negligible other particulates take a larger share.
- IngvarLynn 6y agoIn typical ICE scenario tailpipe accounts only for a half of particulate emissions, another half comes from from brake, tyre and road wear. http://publications.jrc.ec.europa.eu/repository/bitstream/JRC89231/jrc89231-online%20final%20version%202.pdf http://publications.jrc.ec.europa.eu/repository/bitstream/JR...
- hinkley 6y agoIt's a failure of priorities that I see a lot at work and push back on. The need to act is based on the magnitude of the problem relative to your desired outcome, not relative to the current state of affairs. If you don't do this at the beginning, then 'new' things will pop onto the list as you go along, resulting in solutions that are anywhere from suboptimal to maladaptive. Looked at holistically, you might notice that 3, 5, 7 and 8 all have the same root cause, and taken together they may be the 1st or 2nd largest problem. They may also be easier to fix. But no, we're gonna start at the top and work our way down until people get tired of hearing from us.
- antonhalim 6y agoTime to start a new company up and invest heavily in it, VC backed, at scale, revolutionizing the industry. Let's call it AsphaltX.
- wongarsu 6y agoYou joke, but there are plenty of VC backed companies trying to revolutionize road surfaces. The most famous are the various companies trying to add solar panels to roads. Of course Asphalt is pretty awesome on balance, so most of these startups fail spectacularly.
- UnpossibleJim 6y agoI was actually looking for the comment about the solar roadways in here. I know they are expensive up front, but can lead into charging stations to help offset their cost in the long run (if people are willing to go along with either state run charging stations or privatized roadways). The question is, have there been studies about their environmental impact over X amount of time? I think it was Sweden who put in a length of roadway to test their viability for use.
- wongarsu 6y agoThe idea in principle is solid, most roads are empty most of the time and just sit in the sun. But making a surface durable, keeping the it clean and transparent but also providing good grip in all weather conditions are all hard problems. Solutions to one of them often make the other two worse, and many attempts choose materials that fail spectacularly at all three when tested in the real world.
- MayeulC 6y agoMaybe we just need to put those solar panels between train tracks, then? Still a lot of unused surface, can use the rails as conductors, easy to clean using a special car. The downside is that it makes it hard to pour ballast. It also doesn't help at all for road surface (lower their cost or replace "polluting" asphalt).
- NikolaeVarius 6y ago> Concrete creates greenhouse gas I guess its time to also shame walkers and sidewalk bikers
- cjsawyer 6y agoThe biggest con that we’ve bought as a society is the push towards personal responsibility in carbon emissions rather than addressing the bigger sources in large ships, energy production, materials manufacturing, etc.
- jagannathtech 6y agoThose bigger sources are created to serve the personal needs. glaring eg. Industrial animal farming
- aha21 6y ago> But this building block of modern civilization may eventually suck some of that carbon dioxide (CO2) back up—enough to cancel nearly a quarter of the gases released making cement, according to a new study. If you click into the article, it actually contradicts the title. Another click-bait example.
- gwbas1c 6y agoAsphalt driveways start out as very dark black, and then slowly fade to grey. They also start out as very smooth, but as they fade to grey they become more textured. I wonder if there's a relation?
- winrid 6y agoThat applies to any asphalt road. Basically that's the binding agent (which contains oil) wearing off the surface. https://www.quora.com/Why-do-roads-turn-grey-when-they-get-paved-black?share=1 https://www.quora.com/Why-do-roads-turn-grey-when-they-get-p...
- hinkley 6y agoAny cyclist and most road workers I expect are saying, “no shit, Sherlock” right about now. That stuff reeks. It’s awful. And we lay it a mile at a time.
- deleted 6y ago[deleted]
- nickjj 6y agoAnd it lingers for a really long time. In suburban neighborhoods it's common for folks to repave their driveway from time to time. You can usually still smell it for 4-5 days after it's been applied. Anyone who walks down your block will notice it.
- cdent 6y agoYeah, have to wonder how this wasn't already completely obvious. I mean, sure, it's great that it's got an official science stamp on it, but really big duh here.
- 7952 6y agoPeople have terrible intuition about this kind of stuff. Just look at the number of people installing wood burners for evidence of that.
- Balgair 6y agoThe problem is that there isn't much of an alternative. Municipalities have limited funds for roads. And the roads need to be of a certain quality standard, usually set at levels above the municipality. Safety, speed, cost, etc. all must be factored in. Concrete will do the job, but it's expensive, takes time, and is climate variable. You could use dirt, but then safety and speed are lessened. Wood is possible, but it'll need to be replaced a lot. Gravel is also used, but then road capacity is diminished. Asphalt is in a bit of a sweet spot in terms of many variables. Grady of Practical Engineering on YT has a good series on roads here: https://www.youtube.com/watch?v=PIK6I6Q58Ec&list=PLTZM4MrZKfW8JLYNhJe2uWNa0eIfent3B https://www.youtube.com/watch?v=PIK6I6Q58Ec&list=PLTZM4MrZKf...
- iancmceachern 6y agoAlso, tire particulates are a large contributing factor to air pollution, much worse than what comes out of the tailpipe. https://www.tiretechnologyinternational.com/news/regulations/pollution-from-tire-wear-1000-times-worse-than-exhaust-emissions.html https://www.tiretechnologyinternational.com/news/regulations...
- ndonnellan 6y agoTire particulates are worse than _exhaust particulates_, not necessarily emissions, an important distinction. CO and CO2 are not counted as particulates.
- ehnto 6y agoNot to forget NOx emissions from diesel motors.
- ouid 6y agoI don't think you understand what they are measuring here. There are a lot of interest groups dedicated to selling oil until there is no more oil to sell, and they have no interest in being transparent about what they mean when they say that tires are worse than internal combustion. It's pretty clear that the authors are redefining pollution pretty extraordinarily to justify their claims. Only "particulate" counts as pollution, and the lifetime of that particulate, both chemically, and the airborne lifetime, is not even considered. Probably by this measure, the dominant source of pollution on earth is the winds from Africa depositing silt in the Amazon basin.
- airdropsBMW 6y agoIt's a super cool paper
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- iscrewyou 6y agoFor those really curious about details of asphalt concrete construction on California state highways, check out Section 39 of the Caltrans specifications: https://dot.ca.gov/programs/design/ccs-standard-plans-and-standard-specifications https://dot.ca.gov/programs/design/ccs-standard-plans-and-st... These specifications end up being used by a lot of cities and counties in California as well.
- danschumann 6y agoWe should trust our noses a lot more. If it smells awful it's probably polluting!
- hinkley 6y agoParaphrasing a home brewer on the topic of how/why we've had alcohol for so long: We carry a chemical testing laboratory around with us everywhere - our noses - and it can detect all the ways beer can go wrong and become harmful. We made it, we could tell by smell if it was going to kill us, so we kept making it. Sometime later horrible odors became a hallmark of Progress, and has been paying dividends ever since.
- ehnto 6y agoI used to live rurally but then moved to the city. It is always shocking noticing all the pollutant smells when I return to the city from a stint in the fresh air of the countryside. It's surprising how quickly your body adapts and begins to ignore the pollution. I know it is around me now but I can't smell it.
- saagarjha 6y agoOf course, this isn't always accurate, since sometimes things that smell good are not great either: https://en.wikipedia.org/wiki/Benzene https://en.wikipedia.org/wiki/Benzene. But it's often a good first guess.
- danschumann 6y agoYea I've heard people say they like the smell of gas but I don't. It has a too sharp or burny scent.
- nabla9 6y agoHot asphalt/bitumen is heated petroleum product. Is there any petroleum product that is not unhealthy when you heat it up? Gasoline, kerosene ethylene, propylene, butene.... I can't think of anything?
- Merrill 6y agoLucky they found a use for the toxic waste from oil refineries by mixing it with sand and gravel and rolling it down on roads. On the other hand, as vehicles go electric, there won't be any new asphalt to make roads for them to run on.
- epgui 6y agoHaving worked in road construction, I can say that the amount of diesel fuel that gets sprayed all over the thing during rolling/compaction is abject. At least in Canada, if you spill a liter of anything on the ground you're supposed to file paperwork, contain it, maybe have the environment crew inspect it... Meanwhile they send 5 labourers with no education and 100 liters of diesel fuel to spray all over the ground.
- dboreham 6y agoSmells so good though.