Phoenix may copy effective urban heat island strategies from LA

[Hschlick84]

Withing cutting back on the asphalt which reduces heat, that means all the freeways in Phoenix should be concrete, no pavement or rubberized non-sense. Secondly, discourage the use of gravel in yards and plant more native plants that are drought tolerant.

[cactusland]

Originally Posted by Hschlick84

How long does the whitetop last on the pavement?

In my experience, a very long time. However, lots of factors come into play obviously like drainage, weather, temperature fluctiations, etc. If you search for readups or pdfs, most states have ten year or longer outlooks on how different types of asphalt vs concrete work out in their state in terms of cost to longevity.

[DougStark]

^^^ Good replies, folks.

Yes, I may have over-estimated the amount of stormwater discharged into the riverbeds, unused by us in the cities. But, I do notice that when they plant shade trees in the stormwater basins, the trees grow huge.

Why can't they construct parking lots like this (capturing the stormwater for tree use)?. Cost, poor planning, poor payback?

[Valley Native]

Originally Posted by Hschlick84

Withing cutting back on the asphalt which reduces heat, that means all the freeways in Phoenix should be concrete, no pavement or rubberized non-sense. Secondly, discourage the use of gravel in yards and plant more native plants that are drought tolerant.

Concrete generates plenty of heat also, but I agree in principle about the freeways. ADOT made a serious, costly blunder by laying rubberized asphalt on top of concrete freeways. It requires far more maintenance than standard concrete because it certainly doesn't last very long before cracking & chipping. Also, I agree about gravel yards. They're unattractive and they add more heat, which we definitely don't need any more of.

[Magnum Mike]

Originally Posted by JGMotorsport64

In theory this sounds great. But in practice? Our canals and streams are already over appropriated and what storm runoff?

The only way to accomplish this feasibly is to dramatically improve and make more efficient our ability to treat wastewater.

Similarly, forest preserve in Chicago cannot be accomplished in Phoenix and that is why our preserves are desert, because we are in a desert...

That said, we could do a lot better with shade trees in central Phoenix. Tucson, for example, has a lot of shade in its downtown area thanks to a olive trees. We would need to use drought tolerant trees that create shade.

I know something about the science of climate and one possible way to combat heat rising from asphalt surfaces is to use some sort of a misting system to spray water mist on or above road surfaces in the hottest summer months, and one possible source of water would be to use processed waste-water, with the misters installed on top of light poles or other objects above street surfaces, and moisture from those misters would suppress the heat that rises from asphalt road surfaces. I'm not saying to get the streets wet and anger those who want to keep their vehicles clean, but use them like they do in a lot of places with outside areas where people gather, like restaurants. The one benefit besides the cooler road surfaces would be more monsoon rain, which used to occur a lot more in the Phoenix area before its explosive growth we've seen in recent decades. Of course there could be one negative side-effect from this, and that is possibly raising the humidity levels.

Maybe that's something for city officials to think about..

[Magnum Mike]

Originally Posted by DougStark

Hi, I saw this segment on one of our local 10pm news programs recently re: ways to reduce Phoenix's urban heat island.

In summary, the news story said that LA is testing out a light-colored "coating" on hot asphalt pavements. The heat reduction for people walking on the cooler pavement was significant! Whether this will decrease our valley-wide overnight low temps in summer is still unknown, I believe.

The news show said Arizona officials are waiting to see the final results of the LA study before going ahead with a sinilar project here. Unfort the coating isn't cheap, which begs the question: why can't black asphalt streets just be spray painted a light color with oil or latex paint for example? Would the paint make the roads slick in rain? I don't know.

L.A.?s mayor wants to lower the city?s temperature. These scientists are figuring out how to do it - Los Angeles Times

They are working on something to create white road surfaces..

Scientists working to beat the Valley heat with painted asphalt

I'm sure.. or at least I hope they're using paint or material that endures the amount of traffic driven over it for a long time, and not your average everyday paint from the Home Depot..

The binding material used in asphalt is oil-based so it's always going to be black unless they figure out a way to make it white by coming up with a different material that's white.

[BIG CATS]

I'm just curious how much all these efforts will actually help? At night we might see a slight cool off, but I don't think it will be drastically noticeable.