At what locations do bridges typically freeze compared to roadways?

Bridges typically freeze before other parts of the roadway due to several factors related to their design and exposure. Unlike regular road surfaces, bridges are exposed to air both above and below, allowing cold temperatures to affect them more directly and rapidly. As a result, when temperatures drop, the air cools the upper and lower surfaces of a bridge simultaneously, leading to quicker formation of ice.

In contrast, roadways are often insulated by the ground beneath them, which retains heat and can keep the surface temperature slightly warmer for a longer time. This difference in exposure and insulation means that a bridge will ice over more quickly than the surrounding roads, posing a significant hazard for drivers who may not expect icy conditions on a bridge that may seem otherwise safe. Understanding this phenomenon is critical for safe driving, especially during winter weather.