Ontario Bus Driver Knowledge Practice Test

As temperatures drop below freezing, overpasses will freeze first because they are more exposed to the cold air and do not have the heat from the ground to help keep them warm. Underpasses, on the other hand, are protected from the cold air and can retain some heat from the ground. Main roads may also have some heat retained from passing cars, while sidewalks may have some warmth from buildings or from foot traffic. However, overpasses are most likely to freeze first due to their exposure to the elements.