It's Not Just Cars That Make Pollution. It's the Roads They Drive On, Too (sciencemag.org) 64
An anonymous reader shares a report: The smell of summer in Los Angeles, or any major city, is often tinged with asphalt. A freshly paved road or a new tar roof doesn't just wrinkle your nose, however: A new study suggests fresh asphalt is a significant, yet overlooked, source of air pollution. In fact, the material's contribution to one kind of particulate air pollution could rival or even exceed that of cars and trucks. "It's a super cool paper," says Allen Robinson, an environmental engineer at Carnegie Mellon University who was not involved with the research. "Asphalt could be a big, important contributor" to air pollution, he says. Air quality has improved over the past several decades in California and many other parts of the United States, largely because of cleaner exhaust from vehicles and power plants. Despite that, air pollution still contributes to many health problems -- ranging from asthma to heart attacks. And many sources of air pollution continue to be a problem, from livestock emissions to volatile organic compounds from paints, cleaning products, and personal care products (especially those that contain fragrances, such as shampoo).
Yet, when scientists looked at all the known sources of air pollution in Los Angeles and the surrounding areas, they didn't add up. Some sources had not yet been identified. "Asphalt was something that jumped out to us," says Drew Gentner, an environmental engineer at Yale University who led the new study. The material, made from crude oil or similar substances, contains the kinds of semivolatile organic compounds that lead to some types of air pollution. There's also a lot of it. Gentner and colleagues gathered two types of fresh road asphalt and heated them in a laboratory furnace. They also tested new asphalt shingles and liquid asphalts used for roofing. They reasoned that new material should release more chemicals than older material, and they wanted to see how the emission rate changes as the fresh asphalt ages.
Yet, when scientists looked at all the known sources of air pollution in Los Angeles and the surrounding areas, they didn't add up. Some sources had not yet been identified. "Asphalt was something that jumped out to us," says Drew Gentner, an environmental engineer at Yale University who led the new study. The material, made from crude oil or similar substances, contains the kinds of semivolatile organic compounds that lead to some types of air pollution. There's also a lot of it. Gentner and colleagues gathered two types of fresh road asphalt and heated them in a laboratory furnace. They also tested new asphalt shingles and liquid asphalts used for roofing. They reasoned that new material should release more chemicals than older material, and they wanted to see how the emission rate changes as the fresh asphalt ages.
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But it also raises the issue about why tar paper roofs are still a thing as well considering both the emissions issues and the fire hazard they provide.
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Agree. I've never focused on the air pollution aspect of it, but I've always complained about the fact that asphalt roads are just a way for oil companies to dispose of their toxic waste and get paid for it. I've always been more concerned about the runoff, but it's obvious from the smell of fresh asphalt that you're also breathing in a lot of garbage. Once again though, my concern has always been gases like ethene/ethylene. I hadn't thought much about particulates.
I can only hope... (Score:3)
Fresh asphalt is totally worth it. Especially if you have to drive on a rutted, pockmarked boulevard that practically bounces you off the road.
Re:I can only hope... (Score:5, Insightful)
Or... you could pass laws to tax massive SUV's proportionate to the damage their weight does to the roads. Seriously, some SUV's outweigh delivery trucks but they're taxed like they're passenger cars in most states. Same with dually pickups, keep it on the farm Jethro if it's got agricultural plates it shouldn't be on residential roads.
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Or... you could pass laws to tax massive SUV's proportionate to the damage their weight does to the roads. Seriously, some SUV's outweigh delivery trucks but they're taxed like they're passenger cars in most states. Same with dually pickups, keep it on the farm Jethro if it's got agricultural plates it shouldn't be on residential roads.
Road damage starts to become proportional to axle weight to the fourth power, but that measurement is based on a baseline of 18,000 pounds. There aren't any actual numbers, AFAIK, to show that it behaves the same way for low-axle-weight vehicles. It stands to reason that force below some threshold (the specifics of which would, of course, vary considerably based on outdoor temperature) would not cause any damage at all.
Re:I can only hope... (Score:4, Interesting)
There's lots of research showing that low loads do very little damage. Google for "perpetual pavements" or "fatigue endurance limit". However, there is a growing body of work on top-down cracking which seems to be related to tire pressure more than load, although it is not clear how deep these cracks can be driven purely by load.
The fourth power is a generalization from the 1950s. For concrete the power is more like 8, and for asphalt 2. While it is still used for network level analysis and for design of parking lots and local streets, modern design methods use predicted axle load spectra.
That's not to say that SUVs shouldn't be taxed significantly more...
Re: I can only hope... (Score:1)
I dunno where you drive, but where I drive, the bus lane, and the lane most frequented by big rigs are basically the ones that are the most screwed up. Both industries are subsidized by the taxpayer. What're you going to do, tax the taxpayers more? Even a sue-urban expedition HMMWV gen 2 doesn't compare to the damage done by a bus.
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Or go back to using concrete that doesn't fail after 5 years.
Re: I can only hope... (Score:1)
You don't need smooth roads if you have good tires and suspension and are willing to drive at a reasonable speed. Maybe you're driving the wrong type of car for your road conditions?
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No tires and suspension capable of dealing with basketball-sized potholes are available on reasonable passenger cars.
The rougher a road is, the faster it degrades. The rougher a road is, the more it worsens fuel economy and the faster it wears out tires.
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It's been my experience that a well maintained dirt road is better than a poorly maintained asphalt road. And I accepted long that some roads are not compatible with drinking coffee.
I have traveled some asphalt roads that you wouldn't even consider roads anymore, less than 50% coverage just sliding tiles of broken asphalt. Total post-apocalyptic looking stuff. My rather ordinary truck tires traversed it reasonably well. The tires are a fair bit larger in diameter than what you might expect on a compact car,
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Technically speaking, I'm pretty sure that no suspension will handle a pothole better than a typical suspension at speed because the wheel would only drop the tiniest fraction of an inch into the hole under gravity (at 65 mph/95 fps, an wheel passing over a 1 foot wide hole will drop .0193 inches, which is slightly less than a stack of five one dollar bills), but the spring in the suspension forces the wheel into the hole. True the tire is also springy, so it would have to be a sort of solid tire as well. T
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, I'm pretty sure that no suspension will handle a pothole better than a typical suspension at speed
Try it in a go kart. Not only does it snap your spine in half, the kart gets pretty hard to control while going over a bump or hole. A 1938 video [youtube.com] explains why you might want a modern suspension.
Tracked vehicles on the other hand go over pot holes with the greatest of ease. So I recommend that.
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You don't need smooth roads if you have good tires and suspension and are willing to drive at a reasonable speed. Maybe you're driving the wrong type of car for your road conditions?
Maybe they should drive a truck. Choose a 1/2 or 3/4 ton based on road conditions.
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Fresh asphalt is totally worth it. Especially if you have to drive on a rutted, pockmarked boulevard that practically bounces you off the road.
Fresh asphalt is garbage though. Quite aside from it being profitable toxic waste disposal for the oil companies, how long does that road stay nice before it's rutted and pockmarked again? Then how long is it before it's repaved? Most roads are in a state of disrepair most of the time in the US (admittedly, that often also has to do with the fact that they're usually underbuilt). The truth is that asphalt isn't a good construction material. Really, the one thing it has going for it is that it's cheap (becau
Hurray (Score:3)
One more reason to install a Tesla Solar Roof [tesla.com]?
Ah great news! (Score:2)
Particles are also a serious problem. (Score:3)
When bringing in air to the living space, the air filter would become amazingly loaded with particles.
Some of the particles seemed to be tire rubber.
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Most of that is soot and tire dust, though, not road dust.
Paving roads dramatically reduces dust production. Interestingly maintenance costs are about the same per year for gravel roads as for paved ones, but the paved roads reduce dust production massively.
Of course, rail reduces dust far more...
Asphalt wears. The wearing makes dust. (Score:3)
During that "8 to 12 years", apparently some of that asphalt becomes dust and goes into the air.
Unpaved roads obviously allow a lot of dust into the air.
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Yes, some of it does. But more of it just gets broken loose and turns into larger particulates that cause other problems, like being thrown into the air by all terrain tires and breaking windshields.
Most of it not dust (Score:1)
During that "8 to 12 years", apparently some of that asphalt becomes dust and goes into the air.
Just because it eventually needs replacing, does not mean it's going into the air.
Think about it - asphalt is inherently sticky, if anything it acts to scab some other particulates from the air over time.
What does happen is that it eventually cracks in places and chucks or small pieces tend to get caught in tires and eventually fly off the roadside as small gravel. That's why the surface needs replacing from tim
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The amount of material lost directly from asphalt by tire wear is completely insignificant. The main cause of deterioration in asphalt concrete is cracking, which causes the overall layer to lose stiffness and also allows water into the underlying layers. These both weaken the lower layers of the pavement and transfer more load to them, resulting in deeper failures, more movement and thus increased stress and more cracking. This is accelerated by ageing of the asphalt (though the loss of volatiles - this
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No, paved roads cost a lot more to maintain than gravel ones [wired.com].
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Yes, but unpaved roads cost a lot more to use, especially when you add in the externalities.
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No, they don't. What that article is talking about is the cost of re-paving roads that haven't been maintained.
Gravel roads deteriorate faster, but are cheaper to service. Paved roads which are built correctly cost much more to put in, but degrade much slower. Crappy paved roads deteriorate more quickly, and have to be re-paved.
If you actually maintain paved roads, the maintenance costs about as much as maintaining gravel roads. But they are expensive to install, and if you skip maintenance then you wind up
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Material in asphalt roads that becomes dust (Score:2)
That has been my experience; there is material in asphalt roads that can become dust.
Time for the Future (Score:2)
Time for the flying car we have been promised for the last 50 years. Layers of aerial virtual roads stacked one upon another with no stop lights or congestion.
And can you imagine the videos on the subreddit of idiotwithcars? Multiple new degrees of freedom of idiocy.
Haven't there already been many studies about it? (Score:2)
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Re:Haven't there already been many studies about i (Score:4, Informative)
Yes, 96 references and they managed to miss nearly all of the previous work... Maybe they should contact some experts [ucdavis.edu], or at least asked a pavement engineer.
This is a particularly egregious omission: Farshidi, F., Jones, D., Kumar, A., Green, P. G., & Harvey, J. T. (2011). Direct Measurements of Volatile and Semivolatile Organic Compounds from Hot- and Warm-Mix Asphalt. Transportation Research Record, 2207(1), 1-10. [sagepub.com]https://doi.org/10.3141/2207-0... [doi.org]
It's a pity that the conference [ucdavis.edu] that could have helped them as had to be postponed. That site has links to the first four conferences which might help them find some more resources (and help Science Advances find some better reviewers for their pool).
So, it's not just roads... (Score:4, Insightful)
Asphalt is used for all sorts of things besides roads. Not to mention that the vast majority of asphalt removed from roads is actually recycled back into useable paving materials.
I suppose that the emissions it produces are now significant, but that just goes to show that our past efforts to clean up our air and water have paid off and we are now worrying about this source of pollution. Compared to the 1970's, this is nothing.. What's next, emissions from perfume?
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Compared to the 1970's, this is nothing.. What's next, emissions from perfume?
Well, they do mention shampoo. "personal care products (especially those that contain fragrances, such as shampoo)".
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Compared to the 1970's, this is nothing.. What's next, emissions from perfume?
Nothing wrong with continual improvement. It has all proven to be worth it so far.
But yeah - let's wage wars on colognes and perfumes. Naturally occurring VOCs are what makes food smell and taste good. But too much or the wrong ones can cause damage. Repeated damage can lead to cancer. Now that smoking in shared public spaces is banned in a lot of areas, I'd like to move ahead to limit the amounts of fragrance that can be taken into those same spaces.
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Lots of stuff make my body go bonker like sprays, food, perfumes, etc. :(
National Emissions Inventory (Score:4, Informative)
As usual, there are politics involved with who estimates which categories (State, Local, and/or Tribal agencies vs EPA) and all agencies have to choose which categories to focus their limited resources on.
Speaking as someone who spent almost a decade working on emission inventories, the best chance of getting the estimation method improved will be to develop a model that uses as few inputs (and ideally publicly available) as possible so busy staff can get calculations using a straightforward process.
Read more about the NEI at https://www.epa.gov/air-emissions-inventories/national-emissions-inventory-nei [epa.gov]
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And you figure the alleged administration's EPA is going to regulate anything unless some other group is holding their feet to the fire?
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The NEI is then fed into more specialized models (See https://www.cmascenter.org/ [cmascenter.org] for some examples) which then are used to forecast things like Ozone color ratings, or as ammunition (for and against) in the fights to create new regulations or roll back existing ones.
Some groups may use it to show how many fewer ER visits happen if a category is regulated, while other groups may use the same inventory to point ou
Concrete vs Asphalt (Score:3)
Concrete road surfaces are superior in every way to asphalt except one: Upfront cost. They last longer, you get better fuel economy when you drive on them, and they create less pollution when being laid.
But we rarely make them because our short-term budget needs seem to outweigh our long-term planning abilities.
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The albedo on concrete is higher too, which helps with the heat island effect.
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Superiority actually depends on location - concrete stands up to cold weather much more poorly than asphalt, so in the northern US climates it's prone to cracking. Repairing cracked concrete roadways (or driveways) is also quite a bit more expensive. Conversely, of course, in hot climates asphalt with its bitumen binder can literally liquefy, so you've gotta pick your materials appropriate to your location.
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If they did something about two of the causes of that cracking, concrete roads might stand up better. One of those causes is frost heaves. Asphalt will tend to deform a lot more than concrete, which can sometimes save it from cracking right away. The thing is, the frost heaves are entirely the consequence of governments being unwilling to pay the upfront costs of building the roads properly to start with, which leads to more maintenance costs in the end. It's a matter of making the road bed deep enough in t
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In every way? Those laid in sections have these annoying seams that you feel as you drive over each and every one of them. They're miserable. Also, concrete takes way longer to be usable after laying it down.
If we can work out a way to solve just the seams issue, I'd be all for whatever huge project is required to double the lifespan of our roads.
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Far from every way. They don't drain water, they contribute a shit-ton to road noise and make for a very poor driving surface. Concrete additionally leads to better traction and improved stopping distances only when the surface is new. A worn concrete road makes for very poor handling compared to a worn asphalt road. They may create less pollution when being made but they are a heck of a lot more pollution intensive to manufacture in the first place with Asphalt being essentially a byproduct of fuel refinin
Re:Concrete vs Asphalt (Score:4, Interesting)
The problem is a lot more complex than that, and it's not true that it is used rarely. All pavement projects are required to have Life-cycle Cost Assessment (LCCA) as part of their planning (at least those using federal funds in the US), and that is used as one of the primary factors in choosing the design. In most cases for new freeways concrete will be cost effective over a 40-year design life, which is why you'll see it almost exclusively used in these cases (except in freeze/thaw environments, as another commenter noted). For low volume roads and for urban streets asphalt tends win out, mostly because the maintenance cost savings are low in environments where seal coats can be used.
When it comes to maintenance and rehabilitation PCC is typically much more difficult to justify, especially since the development of long-life AC pavements. There is some current work on PCC overlays and bonded concrete overlays, but these are not often done, especially in environments where the road height cannot be changed. In urban environments in the US (because of crazy right-of-way laws) concrete is often a non-starter because it cannot be repaired effectively when trenched.
The road user cost differences between asphalt and concrete are also not that different, nor are the heat-island effects (despite a lot of paid shilling for the concrete industry). Concrete tends to have worse skid resistance, spray and noise if not regularly ground. But then asphalt has rutting and bleeding problems. Where concrete does often win out is when you look at risk - concrete roads tend to have less variance in long-term performance, so have much lower risk.
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It's not just the stopped bus, although that's a big part of it. Asphalt concrete is a visco-elasto-plastic material, especially at high temperatures, so it has some unrecoverable strain under high static loads. Bus stops are particularly bad because you have identical vehicles stopping as close to the same spot as possible. But there is also 'shoving', where the horizontal forces from braking and, to a lesser extent, the torque from accelerating push the asphalt. If you're at an intersection with lots
Roger Rabbit was right... (Score:5, Insightful)
Oil, gasoline, asphalt, cars... add in tires and concrete and you have the list of manufacturers who bribed the LA city council to tear up their streetcars and build freeways. Judge Doom wins in the end.
radioactivity (Score:3)
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I think you've just discovered the solution to the power plant nuclear waste problem. Wouldn't it be nice if the level of radioactivity could be chosen to melt snow but not hurt people?
RTG roads, Mark Watney would approve https://the-martian.fandom.com... [fandom.com]
What about the farts? (Score:2)
Wait until they discover that it's not just cows that fart - people do too! Except for pretty girls.
La Brea tar pit emmisions. (Score:1)
When is the EPA going to come down on LA to clean-up the La Brea tar pits?
I worked with asphalt for over 20 years (Score:2)
Another downside to concrete (Score:1)
And another thing (Score:2)