As winter weather brings freezing temperatures, snow, and high winds to regions across the country, Virginia Tech Transportation Institute expert Thomas Dingus says that driving when both visibility and traction are impaired by the weather increases the risk of a crash by 70-80 percent.

Researchers at the Virginia Tech Transportation Institute (VTTI) are able test wintry driving conditions by simulating fog, rain, snow, and ice on the Virginia Smart Roads, which is a state-of-the-art, full-scale, closed test-bed research facility located in Blacksburg, Va.

As noted in his book, Survive the Drive: A Guide to Keeping Everyone on the Road Alive, Dingus says that “bad weather is clearly a time when you need to adapt appropriately to the conditions as the risk of a fatal or injurious crash is much higher during bad weather. Some of this risk is due to traction and momentum, but a large component of this increased risk is also visibility. Stay engaged in the driving task, keep your eyes on the road, and slow down when traction or visibility is limited.”

Safety Tips for Driving on Wintry Roads:

Based on VTTI research findings, Dingus offers the following tips for drivers in a very low visibility situation.

1.     Slow down, thinking about how far you can really see and how long it takes your car to stop. You don’t want to drive faster than you can see to stop. This means going slower than you probably think is necessary.

2.     Focus on the road. Actively search for any signs of cars ahead, even though it is not particularly pleasant to stare into a uniform scene of fog or snow. Don’t get distracted and don’t look away from the road.

3.     Turn on your lights, typically on low beam. This helps you see a bit better, but it also makes you more conspicuous to drivers behind you.

4.     Don’t become a target that others can’t see. In general, stay out of the left lane. If you are going really slow or need to stop, turn on your emergency hazards to increase conspicuity for those traveling behind you. Consider moving over to the shoulder if you can, at least until traffic backs up well behind you.

“When traction is low, you have to think a lot about momentum. Momentum is the quantity of motion of a moving object, all mathematically defined as mass (weight) times speed,” says Dingus. “If you are driving in a straight line on very slick roads, your vehicle will tend to keep going straight and remain at the same speed. Steering and braking are much less effective in such a scenario because the traction is so low that the tires don’t grip to exert much force, even if you have a four-wheel-drive truck.”

Dingus offers the following tips for drivers when traction is low.

1.     Control momentum by driving much slower, particularly if the roads are icy.

2.     Planning ahead will also help you. Begin braking gently much farther in advance than you normally would to avoid skidding.

3.     If you are going downhill, drive even slower and begin to slow down even farther in advance because gravity is working to literally pull you down the hill.

4.     The same is true with making a turn. Brake gently way ahead of the turn and slow way down before you have to turn. If you wait too long and brake or steer in the curve at too high of a speed in bad weather, you will go straight, no matter what you do with the steering wheel.


About Dingus

Thomas Dingus is director of the Virginia Tech Transportation Institute (VTTI), an endowed professor of Virginia Tech, and is the president of VTT, LLC. He has performed transportation safety and human factors research for more than 35 years, focusing on crash risk, automated and connected vehicles, driver distraction and attention, the safety and usability of advanced in-vehicle devices, crash avoidance countermeasures, and fatigue.

Interview
To secure an interview with Dingus, please contact Shannon Andrea in the media relations office at sandrea@vt.edu or 703-399-9494 and Anne Deekens at VTTI at adeekens@vtti.vt.edu or 540-231-1548. Virginia Tech's television and radio studio can broadcast live HD audio and video to networks, news agencies, and affiliates.