[ChrisLomont]

I cannot find anywhere listing road temperatures nearing 175 F. Do you have a source?

Most I find are like this [1], which would allow a max road surface temp at 100F air temp at the equator with the sun directly overhead on a perfectly clear day to reach around 148F. (see equation 17 in the paper).

The rest of the literature I have found is similar. I doubt roads in the US south reach 175, and likely not even 150.

[1] http://www.ijirae.com/volumes/Vol2/iss8/01.AUAE10083.pdf

[jhayward]

I personally measured road surface temperature of 165º on a road in Texas a few summers ago. It was a hot day, but not unusually so for August.

The road wasn't even blacktop, it was "tar and chip", which is much lighter in color and tends to absorb less heat than pure blacktop asphalt.

[merpnderp]

On hot days I like to take my laser temp gun and shoot roads and other things, and I've never seen anything over 140F.

[ChrisLomont]

Out of curiosity, what is the hottest background temps you think you've checked in? Any around 100 F ambient?

[pbhjpbhj]

Not parent:

>Dr Howard Robinson, chief executive of the Road Surface Treatments Association, says most roads in the UK that experience a reasonable amount of traffic will start softening at 50C.

>[...]

>And dark road material can absorb a lot of heat. The typical summer ground temperature is higher than air temperature. Robinson says roads "regularly" reach a temperature of 50C and above. (http://www.bbc.co.uk/news/magazine-23315384) //

50 deg C is 122F; but this is UK with air temps of ~30 deg C

[ChrisLomont]

Yeah, I read that too. 30C is 86 F. The OP above mentioned a 100 degree day, 14 degrees warmer, and the formula and paper I referenced above would put the surface temp of the road would also only rise 14 degrees, to 136 F on a 100 degree day.

The OP claimed 150-175 is common on a 100 degree day. No research I can find (except one single author) is anywhere near that amount.

[mrkstu]

Asphalt in Arizona can get as hot as 170 [0].

[0]https://gizmodo.com/5807171/phoenixs-emerald-colored-cool-pa...

[ChrisLomont]

First, this is an unattributed claim, and it's referencing 120F ambient, not 100 ambient the above claimed. (Well, it's vaguely attributed to a company trying to sell a solution....)

Given the all time high temp in Phoenix was 122F [1], I suspect this article is playing loose with the facts implying this temperature is a common occurrence, casting more doubt on the accuracy of the 170 claim. From a quick search, only two months in history recorded temperatures above 120, while the article implies this is common. It is not.

So yes, you can find people (like the above) stating these temps without attribution. I've not found anything in academic research with temperatures anywhere near that high, and there is a lot of papers on exactly this topic, with plenty comparing models to actual measured temps. I've been unable to find anything empirical in such papers near these claims.

I'm beginning to think these numbers are more folklore than fact.

[1] http://www.intellicast.com/local/history.aspx?location=USAZ0...