Weather 101: Why Do Bridges & Overpasses Freeze First?

Weather 101

Here's Why You Want To Be Extra Cautious On Bridges & Overpasses In The Wintertime.

As you’re driving you may see a sign like the one below.

Bridges and overpasses are notorious for freezing during the wintertime, but why do they sometimes freeze faster than the regular roads? Both are outside in the same weather conditions, so they should be the same temperature right? Not necessarily.

Bridges and overpasses are elevated, allowing air to flow underneath them. This means the air can cool the bridge and overpass down from above and below at the same time.

Air can’t flow under a road when there is ground underneath it, so you can only lower the road’s temperature from above. Plus, the soil temperature (if warm enough) can slowdown the decrease in temperature, or even stop it. Thus, the road won’t be able to freeze as fast as the bridge or overpass.

Icy bridges and overpasses are always a main concern when winter weather moves into the region. Drivers are usually caught by surprise and don’t have enough time to process and react what is happening. Here are a few things to keep in mind if you are ever in such a situation.

  • If you start sliding on ice, DO NOT SLAM ON YOUR BREAKS!
  • Take your foot off the accelerator and let yourself slow down naturally as you try to keep your vehicle in the lane.
  • If you begin to fishtail, turn the front wheels into the turn to straighten out your vehicle. For example, if you start fishtailing to the left, turn your front wheels to the left and vice versa if you are fishtailing to the right.

Of course, the best way to prevent being caught off guard by black ice is to stay ahead of the weather and up to date on the forecast!

Do you have a weather topic you would like to know more about? Send us an email: weather@knwa.com!

Copyright 2021 Nexstar Inc. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.

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