Comment on Anon watches an American flick
spujb@lemmy.cafe 2 months agoPretty dramatic oversimplification that appeals to predetermined biases.
Here is a resource detailing the different types of asphalt mix and their appropriate use cases.
Particularly note the following:
[Open-graded] mixtures should only be used on high- or medium-traffic volume roadways with posted high speeds only.
Which directly refures the idea that using dense-graded asphalt is purely due to “Americans are too poor/cheap.” The benefits of open-graded asphalt mixtures are lost if you apply it to low speed roadways.
No argument against the poor maintenance part though. Cheers 🥯🥛☀️
Tar_alcaran@sh.itjust.works 2 months ago
That source has a pretty significant bias itself. It being from 2001 might be a clue as to why: before polymer-modified bitumen, there were many more downsides to using open asphalt mixes on anything but long, straight highways. That’s probably also why it only mentions hot-mix asphalt, which the Netherlands is basically banning next year for environmental reasons in favour of warm-mix. I REALLY hope this isn’t the latest version of this book.
It’s true that high-speed roadways more greatly benefit from open asphalt, but it’s very much not true that open-graded mixtures don’t have benefits at lower speeds. They still reduce road noise by 5-7 db even at 50kph speeds, and of course the benefits of less water on the road is substantial. The downside is that there is more fraying, so using it at traffic lights or roundabouts is not a great idea. Even with modern PMB mixes and SAMI treatmeants that reduce fraying pretty effectively (which didn’t really exist in 2001 when that source was composed), a stone-mastic asphalt is still the go-to for areas with a lot of turning or braking.
But most of all, it’s more expensive to build and to maintain, and since maintenance is already pretty crap in a LOT of places (having 6 or 7 lane accessroads doesn’t help there) using open asphalt is probably a bad idea.
Source: Married a Dutch engineer, worked on a lot of roadbuilding projects myself (admitedly not in the design phase, I do know what gets put where here in the Netherlands).
spujb@lemmy.cafe 2 months ago
Thanks for sharing!
Tar_alcaran@sh.itjust.works 2 months ago
No, what I said is that you can absolutely use open asphalt outside of freeways, but that the benefit is smaller. Whether or not you want to do it all depends on how you weigh your cost-benefit analysis. Many Dutch cities use it in the city for noise reduction, regardless of higher cost. But if you value things like noise and splash reduction less, then the cost-benefit will land more solidly on “don’t build expensive things”.
spujb@lemmy.cafe 2 months ago
Thanks for the slight correction. Sorry for the misunderstanding.
I still believe that the “poor/cheap” element is not entirely accurate until further evidence is provided. You yourself point out that it is a matter if cost-benefit analysis, which can be tremendously swayed by land use (noise reduction matters less with lower density) and practical considerations (America is just… really really big).