MCDOT News & Updates

Posted on: June 18, 2017

Fact or Fiction? How heat affects transportation

Fact or Fiction: Heat and Roads

It’s hot out there!  And if you’ve lived in the Arizona desert for a while, you’ve probably heard some tales about how the heat affects the roadways and our cars.   We sat down with the experts inside MCDOT’s Materials Lab to sort out if there’s any truth behind the myths… or if it’s all just a bunch of hot air.  

Asphalt can melt in high temperatures. 

AltTextFiction.  MCDOT uses a binding system specifically rated for the desert based on the average of the seven hottest days of the year,.  The asphalt will appear shiny and may slightly soften, but not to the point where you could make a dent by touching it.

In fact, you might not want to touch the asphalt on a 120 degree day as the road temperature could rise between 140 – 150 degrees. At that temperature skin can experience severe burns within a minute or two.


Tires can melt on hot asphalt.

AltTextFiction. Tires—vehicle and bicycle—are rated for heat. Vehicle tires are made to withstand slightly higher temperature because they generate heat with friction from their speed and rotation.  Not only important to keep tires inflated at the correct pressure, but also make sure you are aware of the age of your tires as older tires are more easily affected by heat.



It’s so hot you can fry an egg on the sidewalk. 

AltTextFact.  Yes!  It’ll take you a while but it can be done.  Sidewalks differ from asphalt because its concrete, and because concrete is lighter in color, it only reaches 10 to 15 degrees greater than the outside temperature.  Our experts estimate it would take someone close to an hour to fry an egg on the sidewalk.



When it gets hot, you can bake cookies on your car dashboard.

AltTextFact. When the temperature outside reaches over 100, there is the potential for temperatures inside the car to reach more than 160 degrees, which is what you need to cookie dough into cookies.   It’s a slow bake though, expect cookies to take a couple hours to completely cook through.




Aerosol hair spray will explode inside a car due to heat.

AltTextFact.  As temperatures rise, molecules inside the can begin to activate, which could cause an aerosol can to explode and cause damage. Not to mention, it would be startling to have a can explode while you’re driving.  Best bet, clean out your car before you hit the road.




Before you hit the road, make sure you and your car are prepared for a safe trip by checking out MCDOT’s Tips to Beat Heat.

What other roadway/transportation heat-related myths have you heard?   Ask us on the MCDOT Facebook page or tweet @MCDOTNews on Twitter using the hashtag #mcdotheat    


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