i see this sign everytime i go over the bridge and i was just curious.
2007-04-27 16:10:33 · 11 answers · asked by mrdaleg 1 in Cars & Transportation ➔ Safety
because the road has the insulation of the earth below it, the bridge just has the insulation of the bridge, so it gets cold faster than the road
2007-04-27 16:12:54 · answer #1 · answered by Anonymous · 1⤊ 0⤋
The road is paved on top of a flat surface where there is no air flow and the earths surface acts as insulation, so the road stays warmer than a bridge that has no insulation under it. The condensation from the warming and cooling cycle settles on the roads and bridges. Since the road is warmer it takes longer to freeze. And some bridges are higher than the road which again freezes faster.
Although there are days that are so cold and the weather changes so fast both will freeze almost simultaneously.
Think of it like this if you had two pipes filled with water and one pipe is insulated and the other is not which will freeze first.
2007-04-27 18:45:16 · answer #2 · answered by Anonymous · 0⤊ 0⤋
You have cold air going over the bridge and under the bridge in the winter time. Bridges are the first to freeze and the last to thaw because of this.
2007-04-28 16:37:01 · answer #3 · answered by ? 6 · 0⤊ 0⤋
The ground retains heat. A bridge is exposed to the wind and has no natural insulation from the cols and will ice over before the road will.
2007-04-28 10:01:32 · answer #4 · answered by Anonymous · 0⤊ 0⤋
The bridge ices because it has air flowing under it, as opposed to the ground under the road. The air flow reduces the temperature of the bridge more than the temperature of the road.
2007-04-27 16:13:08 · answer #5 · answered by InsaneAeroMan 2 · 0⤊ 0⤋
Cold air passing under the bridge deck will allow ice to form before the solid ground under a roadbed reaches the freezing point.
2007-04-27 16:15:28 · answer #6 · answered by mr wizard 3 · 0⤊ 0⤋
the wind under the bridge cools the ground from underneath as well as above, whereas solid ground will retain heat from the sun and all, also, if there is a bridge it is likely over water, a ravine, or both, where the wind is likely to be stronger and colder.
2007-04-27 16:19:39 · answer #7 · answered by montgomery 2 · 0⤊ 0⤋
Dirt's a good insulator. Now under the bridge, what is there? Nothing to insulate it from the cold air so the cold air freezes it from all sides.
2007-04-27 16:13:35 · answer #8 · answered by Anonymous · 0⤊ 0⤋
Because the bridge road surface is suspended in air and subject to wind chill.
The road is built on solid ground and is black to absorb sunlight and hold heat
2007-04-27 16:50:58 · answer #9 · answered by Sal D 1 · 0⤊ 0⤋
Dirt under the road holds heat but
A bridge has air underneath and cools to air temp rapidly .
2007-04-27 16:20:30 · answer #10 · answered by kate 7 · 0⤊ 0⤋