Many of us recognize the dread that comes when the icy weather hits. Driving to work just got a lot more challenging, for you and the drivers around you. Luckily, people have come up with many fixes for icy roads, such as putting down road salt. But what is road salt? How does it work? Is it safe to drive on? If you’ve ever wondered why salt, of all things, helps make it safer to drive in winter weather, this is the article for you. We’ll explain what road salt is, how it is used, if it is safe for your car, and the entire process of how it is used.
Road salt is a variation of basic table salt. It comes in much larger granules and it’s not safe to eat, but it is the same basic thing. Road salt has been used to help drivers handle icy roads since the 1930s, and the science behind it is pretty simple once you know what’s going on.
When water gets very cold, it freezes into ice. Our tires can’t grip on ice, so it becomes hazardous for us to drive. The freezing process is the process of a liquid (water) turning into a solid (ice). During this process, the molecules of water are being rearranged into an orderly solid structure.
Salt actually slows down the process of the molecules being re-arranged. The reason for this is that in order to re-arrange into a solid structure, the water molecules have to be able to “find” each other. Salt is an impurity that gets into the water molecules and slows them down from finding each other. They can’t organize in the way they need to to form a solid, so ice isn’t able to form.
To put it in very simple terms: Water needs to be pure to freeze. When we add something to it to “dirty it up,” it can’t freeze. Pretty simple!
How exactly does road salt “dirty up” the water? Those giant granules aren’t breaking up tiny molecules, after all. Well, to understand that, you have to know what happens to salt when it comes into contact with water: it dissolves! So when we put these large granules of road salt down, the contact with the water makes the salt melt, and then the sodium and chloride molecules are able to prevent the water from forming ice.
Another way that you may hear this explained is that road salt makes it harder for water to freeze at the typical freezing point. So, if it is 32 degrees outside, pure water can freeze. “Dirty” water with salt in it cannot. If the weather were to drop to 20 degrees, though, the water molecules may be able to freeze even with the road salt in the picture. This is important to know as a driver – if road salt gets put down and then the temperature drops even more, chances are the roads will still be very slick.
To prevent ice from forming on the road. When ice forms on the road, our tires have nothing to grip, so they slide. By preventing ice from forming, salt ensures that the road is still coming into contact with the tires, so they can grip. The salt itself is not adding texture to the road to help you grip better – the salt is in the process of dissolving. Rather, it just makes it so that you are able to drive on the road itself.
Keep in mind that the salt is not getting rid of the water at all – just the ice. So, even though you are driving on the road instead of ice, it’s still a wet road, and caution should still be taken as you are driving.
It is true that extensive exposure to road salt can cause corrosion on cars. If you live in an area with a long winter season and you frequently drive over ice, the underside of your car could be getting rusty without you realizing it. The best thing that you can do is to take your car to a car wash that has an under-spray. Be sure to do this periodically through the winter to prevent your car from getting rusty, and you’ll be just fine.
If you live in an area where salted roads are only an occasional thing, you likely won’t notice any damage to your car. One thing to know about road salt is that it can be detrimental to local wildlife and water sources. As the ice melts and the salt-filled water runs off into ditches or streams nearby, it can contaminate the plant life. Be sure that you aren’t letting your dog or cat drink water that has run off a recently salted road during the winter.
In addition to this environmental concern, road salt is also corrosive on bridges, railroads, and other traffic infrastructure. The U.S. actually spends somewhere around seven billion dollars every year repairing the damage done by road salt across the highway and automotive industries.
That’s an interesting process, so let’s dive into it more.
First, did you know that every year, the U.S. puts about 60 million tons of salt on the roads during the icy season? That huge number would be impossible without special trucks used to spread salt over the road. These look a lot like a snow plow, with a mouth on the rear of the truck that spreads salt as the truck drives. The truck is driven over the road and salt is sprayed out the back, leaving behind a trail of melting ice.
This is typically done as soon as it can be when precipitation starts to fall in the winter. The key with salting the road is to get it done before the water freezes, so most cities and towns will have crews doing this in the snow, rain, or hail before the freezing can occur. They may also have salt put down pre-emptively if freezing rain is predicted in the forecast.
As you can see, using road salt is a bit of a controversial topic. While it can be corrosive and dangerous for the environment, it also helps to prevent thousands of traffic accidents on icy roads every year. In fact, the American Highway Users Alliance did a study that showed that using salt reduces 93% of winter-time traffic accidents. In other words, road salt prevents almost every accident that would have occurred without it.
That’s a hard statistic to ignore, and it’s why so many states still use road salt despite the many concerns that come with it. It’s also a cheap alternative to other de-icing materials, which is great news for taxpayers.
Overall, road salt is not going anywhere. It’s simply too effective and too affordable to be replaced, despite the concerns. It’s a good idea to get into the habit of cleaning the underside of your car in the winter if you drive over road salt. You should also be sure to update your insurance policy to prevent winter accidents from draining your savings account. Check out our affordable insurance plans at Freedom National, or get a fast and free quote right here.