IE 11 is not supported. For an optimal experience visit our site on another browser.

How can you drive safely in fog?

When fog obscures your view from behind the wheel of a car, it can turn an ordinary drive into a nightmare. An expert offers advice to keep drivers safe.
/ Source: Dateline NBC

Fog is the mystical paint from nature's palette; it adds a dreamlike beauty to any scenic view. But when fog obscures your view from behind the wheel of a car, it can turn an ordinary drive into a nightmare.

On the Georgia-Tennessee border two years ago, fog caused what looked like a deadly game of dominoes. A 125 car pile up killed four people and injured 40 more. In Salt Lake City last year, a chain reaction crash in fogclaimed one life and sent 30 people to the hospital. And in California in November 2002, Felicia Izzo and her friend Maria Jacobs were on their way to an airport when suddenly fog appeared out of a clear blue sky. Their car crashed into another vehicle, it was broadsided by an SUV, then hit again by a truck. Hurt, but alive, the women scrambled out of the shattered back window.

It turned out to be the largest accident in California history. Nearly 200 vehicles collided that day, 100 people were injured – though, miraculously, everyone survived.

Nationwide, the number of pile-ups caused by fog is staggering. In the last two years, more than 1000 cars and trucks stacked up on the nation's highways.

Fog is essentially a cloud caught on the ground. It's created when warm moist air mixes with cold air and it can cause visibility to drop to less than 50 feet in a matter of minutes. But we'll show you how to get out alive if you're ever caught on a foggy road.

Ron Gibbons: “If you follow a few simple rules you can go through fog safely.”

Ron Gibbons is a visibility expert. He leads a team of engineers at Virginia Tech's Transportation Institute which conducts studies for the auto industry and the federal government on car safety, and on products designed to improve visibility on the road.

At the Institute, Gibbons doesn't need a meteorologist to predict the weather. Like a wizard he can create his own. An obstacle course on a two mile test track is called the smart road. It's the only one of its kind in North America. With the push of a button, machines cover this high-tech highway with rain, snow, or on this morning, fog.

We got a first-hand lesson from Gibbons on how to drive safely in fog. Would you know what to do and what not to do?

Rule #1: Use wipers, defroster and low beam head lights

Rob Stafford: “That is a scary looking fog bank. What is the first thing I should do?”

Gibbons: “Put on your windshield wipers and your defroster. You should also turn on your lights.”

Stafford: “Common sense tells a lot of people you're going to get more visibility with high beams. I'm going to put those on.”

But putting on the high beams was my first mistake. A member of Gibbons' team plays a pedestrian and astonishingly in the bright lights, he disappears.

Stafford: “I would have hit him.”

Gibbons: “Yeah. That's with high beams. If we cut down to low beams.”

As I switch to low beams, the situation changes. 

Stafford: “Now I see him right here.”

Fog reflects the light you shine into it, Gibbons explains. so if you use your high beams, all that light is reflected right back into your eyes, reducing visibility.

But about those fog lamps some cars are equipped with? Well, Gibbons says in his opinion, you're better off using your low beams because fog lamps can also emit too much light.    

Rule #2: No sudden moves

Next, your instincts might tell you to slam on the brakes, after all you can't see where you're going.But gibbon's says that's wrong.

Stafford: “You drive around a corner and suddenly you hit a fog bank like this. Right now, I want to hit the brakes.  What should I do?”

Gibbons: “You can ease off the accelerator. Slow down slowly. Don't do anything rapid or sudden.  Because that's totally unpredictable to the people behind you.”

Slamming on your brakes could initiate a pile-up, especially on a crowded expressway. Gibbons says in heavy traffic cars tend to pull closer together. This reduces the space between your car and the one in front of it, so when traffic slows down suddenly, you have less time to react.

Gibbons advises reducing your speed gradually, while tapping on your brakes. The intermittent brake lights will warn drivers behind you that you're only slowing down, not coming to a complete stop. So he warns, don't ride your brakes. Uninterrupted brake lights signal you're going to stop when your intention is to keep moving along slowly in traffic. This is the best way to prevent a chain reaction crash.

Rule #3: Keep your distance

And here's some more advice, focus your attention on the car in front of you.

Stafford: ”Having a car in front of me is a huge comfort factor cause now I can see something.”

Gibbons: “But your natural reaction is to actually pull closer to that vehicle -- which is exactly what you don't want to do. You want to back off as far as you're comfortable to give yourself as much of a time to react to the situation as possible.

Stafford: “So how close can I be to this car?”

Gibbons: “Well, you can judge that based on if you can see skip marks.”

Skip marks are the broken lines in the center of the road. They're usually spaced 40 feet apart. Gibbons says at a speed of 25 miles-per-hour you should have at least three skip marks between you and the car you're following. 

Gibbons: “And if you can see three skip marks, that's 120 feet. It takes about 120 feet to stop a car at 25 miles-an-hour.”

If there are no skip marks or you can't see them, try to increase the distance between you and the vehicle in front - but not too much or you'll lose sight of it. Leave just enough space between the cars, so that you'll have time to react if the car in front makes any unpredictable moves. Gibbons says if everyone followed this rule there would be fewer cars involved in pile-ups.

Rule #4: Pull over and get out of the car

But what if the fog thickens so you can barely see?

Stafford: “What is our visibility right now?”

Gibbons: “About zero.”

Stafford: “I have no cars in front of me I can't see either way, what should I do?”

Gibbons: “Pull over to the side of the road, as far as you can get off to the side of the road. Stop and put on your hazards. If you can safely get out of the car, get out of the car, get away from the car climb up a bank and wait for the fog to clear.”

Which brings us to the fifth and what may be the most obvious rule.

Rule #5: Don’t drive

If fog is forecast, don't drive. 

Gibbons: “If you don't have to drive, don't drive. That's the safest way.”

You can't always predict fog but Gibbons says you can control your reaction to it. And following a few simple rules should lead you through even the foggiest of roads alive.