Driving in Bad Weather

by Tony Scotti

Most of the driving public can opt out of driving in bad weather – but CEO’s didn’t get to be CEO’s because they stayed home when it snowed. So there is a part of the driving population that has no choice but to drive in weather that sane people would avoid. Part of that population is Security/Executive Drivers. When the weather goes bad consideration has to be given to what you drive and how you drive it.

HOW YOU DRIVE
Changes in the weather conditions can challenge the most experienced driver. As an example:  Driving from dry conditions to ice decreases the capability of the vehicle by 65%, driving from snow to ice decreases the vehicles capability by 49%. This decrease is the laws of physics at work.  When moving from one surface to another; you are suddenly driving a car with much less capability. And to make life more exciting this change in capability all happens in tenths of seconds. This quick change in vehicle capability would be difficult for the most experience driver to control. 

WHAT YOU DRIVE - 4WD/AWD
There are so many options to choose from that it is easy to get confused by all the different drive systems offered by the car manufactures.  There are 3 basic systems - Part-time 4WD - Full-time 4WD, and AWD. We could spend a lot time talking about the differences between them all but AWD is best for bad weather, and 4WD is close behind.
But - No 4WD or AWD system will make driving safer, especially in snow and ice. If there is less adhesion between the tire and the road, the vehicles capability is greatly diminished. The problem is that most 4WD/AWD drivers think they have a vehicle that can defy the laws of physics. However, once the vehicle is moving the laws of physics for all vehicles are equal.

Here is the issue with AWD or 4WD – they can accelerate in snow almost as quickly as on dry roads, but that does not mean they stop or corner any better than a 2WD system can, in fact 4WD and AWD do very little to help while turning,  and offer no additional braking capability on wet, snowy roads. Once moving, the physics of 2WD, 4WD, and AWD systems are pretty much the same.
Here are some of the general bits of advice.

Changes in the weather conditions can challenge the most experienced driver.

Clean your windshield, back window and side mirrors.

The problem is that most 4WD/AWD drivers think they have a vehicle that can defy the laws of physics. However, once the vehicle is moving the laws of physics for all vehicles are equal.

A 4WD vehicle will do a better job of getting the vehicle moving than a 2WD vehicle. But once the brakes are applied a 4WD is like all other vehicles, the driver is at the mercy of the tire road adhesion.

If you are on a steep hill and in packed snow 4WD is a big help, but if you are on the same hill and the driving up the same hill on ice it’s of very little help.

Only tire chains increase traction of rubber tires on snow and ice significantly.

Although this has been said many times and many ways, stopping on snow and ice may require up to 10 times the distance as stopping in normal conditions.

When you turn the steering wheel to drive around a corner or avoid a problem it makes no difference what drive system you have under you – you are at the mercy of the tire road adhesion – if it is icy and that adhesion is low you could be in for an exciting ride.

This is another one of those warnings that everyone seems to know but most everyone pays no attention to. Be careful on bridges, overpasses and infrequently traveled roads, which will freeze first.

When driving in bad weather the best advice is slow down.