Why do bridges freeze before roads?
You always see the warning signs, but why exactly do bridges freeze before roads?
Have you ever heard that bridges freeze before roads? If you live in a cold climate, then you have become accustomed to watching for black ice and other icy patches when you cross a bridge or overpass. However, why is it that these areas are more susceptible to ice than other roads?
Photo by Aaron Burden
Three reasons bridges freeze fast
There are three reasons bridges freeze fast. The main reason bridges freeze faster than roads all comes down to basic science. You can become a better driver when you are aware of the dangers of bridges when you’re dealing with icy weather.
Photo by Andre Benz
1- Exposure to the elements
There are three basic reasons bridges freeze before roads. The first, and most common reason, is because they have nothing underneath them, shielding them from the frigid temperatures. Since a bridge is open on the underside, it has no protection from the wind and extreme weather. A roadway is built upon the ground, which acts as an insulator during inclement weather. While it may be cold outside, there is warmth deep within the ground that acts as padding. Since bridges are open on all sites, they will ice over quickly.
Photo by Christopher Lee
2- Location matters
One of the other reasons a bridge is so quick to freeze is because of its location. Yes, they are exposed on all sides, but it’s what’s underneath that counts. Bridges cover rivers, creeks, and bodies of water in many cases. Water freezes quickly, creating cold spots. These cold spots make the bridge more prone to freeze than a roadway that doesn’t have these cold areas underneath them.
Photo by Zachary Keimig
3- Construction Means Everything
The last reason a bridge freezes before a roadway is because of its construction. These structures are made of metal, and metal is known as a heat conductor. There is heat within the bridge, but it’s quickly transferred to the surface where it meets the cold temperatures. If the temperature outside is 32 degrees Fahrenheit or below, then the air temperature will cause the warm air to freeze quickly, which makes ice spots on the structure. Roadways are made of asphalt and concrete, and they don’t conduct heat well. Any warmth within the ground stays below as the materials don’t allow it to pass through the blacktop. Too many people think because the roads are clear that they have no worries as they cross a bridge. However, icy patches can exist on these massive structures when the roads are without issue.
Photo by Graeme Cross
Driving on bridges in icy weather
When you are driving on the roads during icy weather, you may not see any ice as you come upon a bridge. Ice can easily mix with snow or dirt and create frozen patches that a driver cannot detect. If you are going full speed, then you can lose control of your automobile when you hit one of these patches. This is commonly known as black ice If your area doesn’t plow, salt, or sand the roads regularly, then ice can accumulate on the bridges, and it becomes a hazardous situation. You should pay particular attention at night, especially when seeing black ice is almost impossible. When the ambient temperature is below freezing, then you should make sure that you use caution. Additionally, you must always assume that there is ice on any bridges.
During the winter months, using snow chains or tires is helpful, especially if you live in an area that receives an abundance of snow. If you should encounter snow and ice, you want to make sure that your tires have enough tread to handle the elements. Having bald or worn-out tires on snowy roads is dangerous, and it can cause you to lose control of your vehicle. If you should start to slide, never hit your brakes. Instead, remove your foot from the accelerator and try to steer the car out of the slide. Making sudden movements can cause your vehicle to fishtail or even flip.
Watch your local weather
You can avoid a lot of mayhem by checking our local forecast. Meteorologists track storms and road conditions, and they will let you know when things are unsafe for travel. Keep your eye on the sky, and don’t try to be a hero in inclement weather. If the roads are too bad to leave your home, then take a snow day. There is nothing worth your life or the life of another person for things that can be put off till the roads clear. Remember, if the temperature drops below freezing, you should always assume bridges may be frozen. Just because the roads seem clear, bridges could be a different story.
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