painting streets to reduce heat

[Seaman]

I've stumbled across this interesting project.

It's about a pilot study in LA where they're painting some streets in a light grey to decrease sunlight absorption and heatup. There's this issue called the "urban heat island effect". The dense conglomeration of concrete and asphalt takes up enormous amounts of heat resulting in the city beeing several degrees hotter than the surrounding area.

Obviously, this is quite a thing for cities like LA.

I'm not sure, though, whether it's a good idea to make a street somewhat reflecting since this possibly blinds people, turning it into a safety issue.

[matias93]

The first thing I thought was "and why not use concrete instead of asphalt + paint?"
If you think on it, it's much better: is cheaper, does use much less hydrocarbon derivatives, its permeable to water (avoiding issues with surface-undersurface isolation and flooding), its naturally whiter and can be tinted much more easily, and its faster to do, as it only requires pouring and flattening the concrete, and not coating it.


But yes, the problem with the glare subsists; maybe the argument there is that the road surface is hardly the main source of glare: suspended dust on the air shines too, as glass and polished surfaces do, and even other cars coatings.


In any case, the best solution to this kind of problem is much easier: to plant big trees on the sidewalks and let their foliage to grow over the roads, keeping a permanent shade and absorbing light instead of reflecting it back to the atmosphere.

[APSMS]

I think asphalt is significantly more forgiving to road laying. Concrete requires significant prep and must be reinforced to prevent stress fractures under load. Additionally the cost of concrete has gone up significantly, at least in the US, in recent years. Asphalt often requires much less prep and can be repaired and resurfaced much easier than concrete, which aside from the prep work involved and the fact that concrete must be laid in relatively small pieces, is why most modern roads are made out of asphalt.

I do agree that trees would be an obvious solution; LA streets aren't always conducive to large overhanging trees but it would simplify things a lot.

[ChiefZDN]

I think asphalt is significantly more forgiving to road laying. Concrete requires significant prep and must be reinforced to prevent stress fractures under load. Additionally the cost of concrete has gone up significantly, at least in the US, in recent years. Asphalt often requires much less prep and can be repaired and resurfaced much easier than concrete, which aside from the prep work involved and the fact that concrete must be laid in relatively small pieces, is why most modern roads are made out of asphalt.

I do agree that trees would be an obvious solution; LA streets aren't always conducive to large overhanging trees but it would simplify things a lot.

However, in Indonesia, lots of roads (especially region other than Jakarta and other big cities) are concreted to make the roads stronger. But, I agree with you. Not only does make the maintenance harder, but also makes the road less 'beautiful', especially if you want to repair the road. The trees are better, not only make the road cooler, but reduce the pollution too.

This reply is corrected with Ginger (I'm not affiliated with it), a proofreader. So, my reply might be unstructured by this. Thanks.

Note: Jakarta is the world's best tree ROI according to a research.

[dyoungyn]

I agree, in the Western U.S. Mountain States such as Salt Lake City, Utah, all the freeways and many parking lots are made of concrete due to the negative effects of salt and de-icer with pavement.  I can contest, concrete is much stronger and more reliable due to wear and tear that pavement not to mention maintenance. 

[Seaman]

Regarding the conrete:
It's a real mess to repair it. My Autobahn A14 (the highway I use the most) was built in a hurry after German reunion. Unfortunately they used a bad composition of the concrete, resulting in most of the lanes suffering from concrete cancer. In order to repair it, they had to cut out the damaged sections. It has been rebuilt for quite some money, but for most of the time, the highway looked like this:


regarding the reflecting pavement:
I still have the feeling that a relaxing high noon walk along those streets reminds me of this: