Bridges and Overpasses Freeze First, Posing Hazards

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Bridges and overpasses in Beale AFB, California and surrounding areas can freeze over before the rest of the road, creating dangerous driving conditions that can last for days. This happens because the open structure of bridges and overpasses allows them to lose heat more quickly than the ground-level road, leading to faster freezing.

Why it matters

Icy bridges and overpasses are a major hazard for drivers, as they can cause vehicles to suddenly lose traction and control. This poses a serious risk of accidents, especially on high-speed highways. Being aware of this phenomenon and knowing what to look for can help drivers stay safe during cold weather.

The details

Bridges and overpasses freeze before the rest of the road because their open structure allows them to radiate heat upwards and lose it more quickly than the ground-level pavement. The ground acts as an insulator, trapping heat and preventing the road surface from freezing as fast. In contrast, bridges and overpasses have air flowing both above and below the surface, causing them to cool down more rapidly and develop ice first.

• Bridges and overpasses can freeze over even when the surrounding roads are still clear.
• The icy conditions on elevated structures can persist for days, even after the ground-level roads have thawed.

What’s next

Drivers in the Beale AFB area should be extra cautious when crossing bridges and overpasses during cold weather, and watch for any signs of icy conditions that may not be present on the rest of the road.