How should the road surface of a bridge be treated?

The correct choice emphasizes that even when air temperatures have risen, the road surface of a bridge can still retain ice. This phenomenon occurs because bridges typically have less insulation than roadways that are surrounded by ground. Consequently, they cool down and warm up more quickly, meaning that when temperatures hover around freezing, moisture can freeze on the bridge surface, creating hazardous conditions for drivers.

It's important for drivers to be aware that a bridge may have ice even if the surrounding area appears clear. This situation may not be immediately obvious, which is why maintaining cautious driving behavior on bridges is crucial during cold weather, especially when temperatures fluctuate around the freezing point. This understanding helps prevent accidents by encouraging drivers to be extra vigilant on bridge surfaces.