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Tips and Tricks for Winter Driving
If you have read the “All About Me” section, you know that I drive a very large, sometimes hard-to-control vehicle all over the country in all different kinds of weather conditions. All too often, as evidenced by the dozens of spun-out cars and jackknifed trucks I see in ditches and medians in every snowstorm, people fail to bear in mind some of the most basic rules of winter driving when they encounter such conditions, and accidents (or worse) can result. There are a few tricks I have learned that the average motorist is never taught in driver education classes, and I’m going to share those with anybody who cares to read and learn.
The most obvious, most basic rule is, of course, to slow down when you travel in wintry weather conditions. Don’t be fooled into thinking you can zip along at normal speeds just because you have anti-lock brakes, four-wheel drive, or traction-control systems; these things, while they are great additions to modern vehicles, still aren’t perfect and won’t keep you out of every possible adverse situation. Excessive speed for the road and weather conditions WILL get you into trouble.
Additionally, don’t be fooled into thinking that just because you drive a pickup truck or SUV, you are automatically any better off in winter driving conditions. There are certain winter-related road conditions in which pickups and SUVs offer fantastic performance compared to smaller passenger vehicles, such as on rural side roads that receive little or no wintertime maintenance (i.e., no plowing) or in other deep-snow conditions either on or off road, but in the vast majority of cases on highways, (sub-)urban arterial routes, and/or city or suburban streets, pickups and SUVs are not necessarily any more sure-footed than any other vehicle.
Beyond this, though, there are other things to consider. One thing that a lot of average motorists are never taught is how to accurately read the condition of the roadway itself, and without that knowledge, you truly don’t know what kind of traction you have. Sometimes a road that appears to be merely wet is, in fact, an ice rink on which you can go skating right into a major accident.
On a road that appears to be wet (i.e., it is not covered in snow), pay careful attention to the area immediately behind the tires of other vehicles, especially trucks. If other vehicles’ tires are kicking up a fine, misty liquid spray (which may look like a fog cloud), that tells you that the road is not frozen and you can safely treat it with the same caution with which you would treat any wet road. This could be the case for two reasons: (1) the road surface has not yet begun to freeze over in falling temperatures, or (2) salt trucks have been out and have salted the roads, chemically melting snow that was on the road earlier.
(Depending on the salt concentration, a laboratory mixture of salt and water can remain liquid as low as –6°F (–21°C); salt is used to de-ice roads because it changes the freezing-point property of water in this way. However, sodium-chloride (NaCl) salt, the most cheaply and readily available de-icing salt, loses 80% of its ice-melting power by the time the temperature drops to 20°F (–7°C), so you best not be counting on the roads having been salted in colder temperatures.)
On the other hand, if you cannot see any liquid spray coming up from a road that appears wet, the road is frozen and likely very slick and dangerous. Reduce your speed by coasting (letting off the throttle) and downshifting at low RPMs if you have a manual transmission; STAY OFF YOUR BRAKES as much as humanly possible, and look into getting off the road at the earliest chance. In such conditions, even 20 mph (32 km/h) may be a dangerously high speed, and you would be better off to get a motel room if you can, or even sleep in your car for the night if you must.
Often times, however, the road surface will not offer uniform traction from lane to lane, or even within the width of your vehicle. Being able to read road conditions is a very important skill in this case, and I’m going to go over as many different possible weather scenarios as I can think of. One very important consideration is the quality of the snow or other frozen material on the pavement: what does it look like?
Freshly fallen, or “powdery” snow, does not pose as great a hazard to traction as other types of winter precipitation when it sits in a thin layer on the road. Powdery snow is compressible, and the weight of your vehicle compressing it down into the pavement will give you a wee bit more “bite” into the pavement. You can pick out powdery snow by its more uniform appearance and a very slight “glistening” visual effect that is most noticeable at night, when you are driving with your headlights turned on. You won’t be able to safely keep up normal highway speeds on powdery snow, but with good visibility, light traffic, and at least two lanes in your direction, you may be able to safely keep up as much as 50 mph (80 km/h).
On the other hand, snow that has a rougher, more irregular appearance has been sitting on the road surface for some time, and has been fully compressed by the hundreds of vehicles that have run over it. On heavily traveled highways such as Interstates and other freeways, you stand a far greater chance of encountering this quality of snow — the thousands of vehicles that pass by every hour will have run over the snow long before the salt trucks can catch up with every inch of road. You will have some traction — driving on this irregular-appearing snow is not as dangerous as driving on ice — but you will need to slow down and avoid sudden maneuvers. (That is to say, you must drive as smoothly as you possibly can — no quick changes in speed, either up or down, and no jerkiness in steering. Be as gradual as you possibly can be when changing lanes, passing, etc..) If visibility is good, you may be able to safely and reasonably go 35-40 mph (56-64 km/h) on this rougher snow, although again, every situation is different and I cannot make any blanket guarantees.
Blizzard or blowing-snow conditions are not necessarily any more hazardous in the traction sense than a garden-variety snowfall, but they cause huge problems with visibility. It doesn’t matter how quickly you can steer or stop without spinning out, if you can’t see down the road at least the distance you will cover in the next 10 seconds. In some blizzard conditions, you may be lucky to be able to keep up a speed of 25 mph (40 km/h), if not even less than that in total “white-out” snow bands. A heavy snowfall of two feet (60 cm) over 15-20 hours often won’t close roads in places with competent state D.O.T. snow crews; but even a small amount of actual snow, if it is whipped up by enough of a wind, can cause enough problems to prompt state highway patrols to shut down roads. (There is a reason why places near the Great Lakes that get a ton of lake-effect snow rarely, if ever, close roads in snowstorms, but places in the Plains that get much less total snowfall have to close their roads much more often — it has everything to do with the higher winds usually found in the Plains.) The key in a blizzard is to maintain a slow enough speed to be able to see the road, so you can stay on it and not end up in the ditch.
Taking a good look at the shoulders will also tell you a lot about the condition of the pavement. If there is still snow on the shoulders, while the travel lanes are wet or slushy, that is an indication that salt trucks have been working on the road and you can (cautiously) treat it more like a wet surface. (Obviously, bear in mind the rule about liquid spray from other vehicles’ tires, as mentioned above.) The shoulders are usually among the last parts of the highway that state D.O.T. crews will get around to during salting operations. On the other hand, if both the shoulders and the travel lanes have the same “wet” appearance, but you cannot see liquid spray being kicked up by other vehicles, you’re looking at freezing rain, and the road is an ice rink.
It is often helpful to have some way of immediately knowing the outdoor temperature. Some vehicles come with this capability built-in; if your vehicle lacks this, however, you can purchase a small LCD-readout thermometer that attaches to your windshield via suction-cups for about $20 at auto parts stores and truck stops. The most dangerous winter weather conditions tend to occur when the temperature is a few degrees below freezing, typically around 28 or 29°F (-2°C); road surfaces almost always tend to stay about 2°F/1°C warmer than the air temperature because of the friction between tires and pavement that keeps you rolling. When the air temperature is roughly 29°F (-2°C), the road surface temperature will likely be around 31°F (-1°C), a point at which anything that has fallen on the road in liquid form will begin to freeze into a thin but extremely slick sheet of ice.
There are some other rules that you need to keep in mind when driving in winter weather conditions. Avoid changing lanes if it is at all practical; unnecessary maneuvers can cause you to lose traction. If you must change lanes, do so very gradually; avoid “whipping out” into the adjacent lane. Additionally, do not attempt to change lanes if you are working your way across an overpass or elevated viaduct; as signs posted everywhere tell you, bridges and overpasses are the first sections of road to freeze, and the most difficult to de-ice, because of their total exposure to cold air with no ground beneath them for insulation. You will by default have less traction on a bridge, and if you try to change lanes, you leave yourself with that much less traction to keep rolling forward.
The same thing is true of braking — you only have a limited amount of traction on a snow-covered road, and braking requires traction to slow you down. You would be far better served to do as much slowing as possible by simply coasting (removing your foot from the accelerator); this means you will have to allow yourself a LARGE following distance. (On dry pavement in good conditions, my rule of thumb is that you are following too closely if you can read the license plate number of the vehicle ahead of you; on snow, I recommend tripling that distance, or at least 400 feet (122 m).)
If you have means of slowing your vehicle other than your brakes, it would be wise to use them. That is, if you drive a car with a manual transmission, you can use downshifting and the natural engine-braking effect to slow your car down — although you will want to keep your engine RPMs low when you do this; you want to avoid the high-torque part of your engine’s RPM range, which is from the mid-range upward, generally speaking. If you are driving a tractor-trailer, highway motorcoach, motor home/RV, or other heavy diesel-engine vehicle equipped with some sort of an engine or exhaust brake, such as the “Jake brakes” typically found on truck tractors, use those as much as you can — the farther you can keep the origin of the vehicle-slowing force away from the wheels, the better. Obviously, you also need to exercise caution in the use of such engine-braking devices; for example, in a tractor-trailer, it would be a bad idea to flip on the Jake and let ’er rip at 2,200 RPM — having an engine brake gives you a little help, but it certainly is no panacea.
While snow is actually falling, it can be difficult to keep your windshield clear enough to adequately see the road, especially in larger vehicles like trucks. Most car windshields are raked back at an angle that is closer to horizontal than vertical; because of this, car windshields are not as directly exposed as truck, bus, and RV windshields are to head-on winds and so-called “ram air” (the airflow past a vehicle that results from the vehicle’s forward motion). Car drivers therefore may not have to worry as much as drivers of larger vehicles about ice buildup on their wiper blades; but that said, there is a way to keep larger windshields clear that I have found surprisingly effective in my experience.
It seems counter-intuitive, but you do NOT want to run your defroster on a warm or hot temperature setting when you’re moving at highway speeds during a snowfall. By using a warm or hot temperature, you’re actually contributing to the ice buildup on your wipers that will eventually render you completely unable to see. What happens is that your windshield becomes warm enough to melt whatever hits it, but as that liquid is picked up by your wipers, it almost instantly re-freezes into ice on the wiper blades. Eventually, you’re left with ice chunks moving across your windshield, and you get a semi-permanent wet streak through which you cannot see at all.
What you want to do is either avoid running your defroster entirely, to the extent that the insides of your windows don’t fog up, or run it at the coldest temperature setting you can stand if you must de-fog your inside glass surfaces. By doing this, you keep your windshield cold enough to ensure that everything that hits it remains frozen; therefore, it can’t re-freeze on your wiper blades and ice them up all to hell. This won’t work perfectly, and its effectiveness is dependent on a number of factors, but it should at least allow you to avoid having to stop every 30 miles (50 km) to get out and remove ice from your wiper blades by hand.
Finally, make sure that you are carrying plenty of windshield washer fluid if you take any kind of long trip through winter weather. Especially in vehicles with more vertical windshields, you will encounter all kinds of salt spray once the salt trucks have been out, and this will quickly coat your windows with a dull grayish-white film that will destroy your ability to see. You will need to use your windshield washer system frequently in such conditions, and the last thing you want to do is run out of fluid just when you need it most. Be careful, though, in certain models of commercial vehicles; some windshield-washer systems on large vehicles are poorly designed, and have a tendency to over-spray fluid onto the vehicle’s exterior rear-view mirrors. The fluid can freeze on unheated exterior mirrors, rendering them useless; and it has a tendency to form a spotty, salt-like film on heated mirrors, which isn’t all that much better.
This guide is by no means exhaustive, but I hope it will help you cope with driving in winter weather. Remember: slow down, pay attention, give yourself more space around your vehicle, and drive cautiously and safely.
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