ROCHESTER, NY (WROC) — Icing accidents can be especially dangerous when wet roads suddenly become pure ice. It happens when temperatures drop rapidly in a hurry, such as after a cold front passes through the area or when the sun goes down.
Wet roadways should be treated with extra caution if temperatures are near freezing, but it's important to remember that even surfaced roads that aren't treated can still form dangerous ice patches. These often appear on bridges, overpasses, lightly traveled or untreated roadway surfaces, and areas shaded by trees or hills.
While it might seem counterintuitive, bridges and overpasses freeze before roads. There are a few reasons for this.
Bridges are usually made of steel and concrete, which conduct heat very well. This means that any heat trapped within a bridge will rise to the surface and be exposed to frigid air from above and below. Roads, on the other hand, are built upon the ground, which acts as an insulator and keeps warmth underneath the surface.
A bridge also has nothing above it to trap heat, so it will lose its warmth faster than a road. And as the temperature drops, this rapid loss of heat causes bridges to ice up very quickly. Roads, however, retain their heat for longer, allowing them to slow down the ice formation process.
