The road surface of a bridge may be dangerous in winter because it may remain icy after the rest of the roadway is clear.
Answers
True
False
The Correct Answer and Explanation is :
True.
The road surface of a bridge may indeed be dangerous in winter because it can remain icy after the rest of the roadway has cleared. This is due to several factors:
- Air Circulation: Bridges are structures that are exposed on all sides to the air. Unlike roadways that are surrounded by earth or have more insulating materials beneath them, bridges have open air underneath and on top, which allows for faster cooling of the surface. This can cause the temperature of the bridge to drop more quickly than the surrounding roadway. As a result, ice can form on the bridge surface even when the rest of the road is clear.
- Temperature Variation: The temperature of a bridge’s surface is more likely to fluctuate rapidly. This is especially true on cold nights or during early mornings when the temperature drops. Ice can form even if the air temperature is slightly above freezing due to the heat exchange between the bridge’s exposed surface and the cold air beneath it. The ground under the bridge doesn’t provide the same warming effect as the rest of the roadway, which is why the surface can remain icy longer.
- Black Ice Formation: Bridges are particularly prone to black ice formation. Black ice is a thin, transparent layer of ice that forms when the moisture from rain, fog, or melting snow freezes quickly. It is particularly dangerous because it is almost invisible to drivers. On bridges, the formation of black ice can be more common due to the rapid cooling of the surface.
- Early Frost and Snowmelt: Even if the roadways are clear due to sun exposure or salt application, bridges can still retain patches of ice or snow, as the temperature near the bridge surface can remain below freezing while the surrounding areas have thawed. The absence of insulating ground beneath the bridge means that it is the first to freeze and the last to thaw.
For these reasons, drivers should exercise extra caution when driving over bridges in winter conditions.