Driving on Snowy and Icy Road Surfaces
My truck’s weight enables it to track more steadily than personal vehicles through rain water but not necessarily over snow or ice. Thick-treaded snow or all weather tires are commonly mounted on the truck’s drive wheels. They provide some extra traction in mud, snow and ice, but are not as effective as you might imagine–on mountain passes and some other grades in snowy and/or icy conditions, chains on at least some drive tires and trailer tires are often required. My truck can plow through loose snow until it gets too deep, maybe over a foot, then the drag causes it to falter. Using the drive splitter (splitting drive power more evenly between rear and forward drive wheels) can help, but the truck and/or trailer can still get stuck and possibly high centered in deeper snow. Driving in mud, especially from a standing start, can also be difficult.
On hard pack and ice a truck’s tracking can get so dicey that the truck can spin out, with the trailer jackknifing (sliding around the tractor so far that its tail and the front of the tractor face close to the same direction). On a slick surface the heavier weight of a trailer relative to its tractor can cause the trailer’s momentum to carry it past the tractor. Frictional heat from the truck’s tires contribute to this hazard by melting hard pack and ice and making tire-to-road contact more slippery. In fact before its tires cool, a truck can still slide after being parked on an icy or hard packed surface. Obviously truck drivers turn off cruise control and slow down in bad weather conditions. Truck skids of any degree feel very unnerving and we take extra care to avoid them. You definitely don’t want to be near a skidding or jackknifing truck.
When “dead heading” (towing an empty trailer) or towing a lightly loaded trailer, my truck and most others are not very stable on slick surfaces and are susceptible to skidding and jackknifing.
Factors affecting road surface conditions and chances of vehicle skids and spinouts include air temperature, wind, types of snow and ice and presence of or lack of sunshine. Temperatures at freezing (32 degrees Fahrenheit) or slightly above, combined with frictional heat from truck and personal vehicle tires, partially melt hard pack and ice and make highway surfaces slick. Sunshine heating increases the melting, making highway surfaces easy to spin out on. In sunshine on a highway drying out following a snowstorm, drivers sometimes get overconfident on remaining patches of hard ice (“boiler plate”).
Falling snow or frost in freezing or slightly warmer temperatures turns road surfaces very slippery. Trucks and personal vehicles generally handle better in very cold temperatures. Snow varies from very large watery flakes to small dry powdery flakes. Snow with high moisture content tends to form slicker road surfaces. Loose untracked or partially tracked wet snow drags on vehicles and hampers traction and stability, whereas dry powdery snow is easier to blow through.
In the winter, wetter snow generally falls on the west coast, on the plains and in the east. I’ve seen more traction problems and spinouts in these regions than on the dry cold snow (“champagne powder”) in the Rocky Mountains. Freezing rain, the dreaded “icy wintry mix” of weather forecasts, more frequently shuts down highways and streets on the plains and in the east. One of the most accident-strewn stretches of highway I’ve driven was on I-90 in the Syracuse-Rochester, New York area, where a storm had left a unique heavy blanket of icy/liquid slurry, too cold for slush but very slippery, with a consistency resembling a Slurpee. Rain on top of snow, then frozen overnight can turn the snow into something resembling slick Styrofoam that is hard to walk on as well as drive on.
Rocky Mountain driving is complicated by high traffic volumes. Slow-and-go skier traffic in the mountains can still warm up drier colder snow into slick surfaces that cause fender benders. Spring squalls in the Rockies produce wetter snow and slippery road surfaces.
Wind can blow isolated drifts onto otherwise dry highways, where traffic packs the snow down into slick patches. High winds blowing against a big box trailer’s large side surface areas can deflect tracking so the rear of the trailer crowds the lane next to it or a shoulder. Very high winds blowing against the side of a trailer can topple a truck, especially a lightly loaded one.
De-icer sprayed by highway maintenance trucks before storms arrive is effective in making road surfaces tackier in icy fog and lighter storms, but gets overwhelmed by large intense snow and ice storms.
Loose snow on the shoulders of interstates or major highways with two lanes in each direction present another challenge. Personal vehicles and trucks tend to pack the middle of the road, staying away from the shoulders. This is because driving with one steer wheel in loose untracked snow and the other on the packed surface can pull a vehicle, even a truck, completely off the highway. Snow or hard pack or ice can hide the center line and drivers tend to crowd or even encroach over it to stay out of the loose snow on the edges. Reduced clearances make passing difficult.
Personal vehicles are just as susceptible, if not more so than trucks, to spinning out on snowy, icy, wet and/or muddy road surfaces. Some drivers don’t check their speeds enough, as evidenced by wrecks along highways and even surface streets. Some probably don’t turn off their vehicle’s cruise control. Everyone should know to turn off cruise control in bad conditions to prevent skidding. And everyone should know to stay off the brake and steer in the direction of a skid until you regain control. If you’re not going too fast for the road conditions you have a chance to recover from a skid safely. The best deterrent to skids and spinouts is always to slow down.
On very slick highway surfaces I slow down to as low as 1/3rd normal speed or even less, 15 to 20 mph (miles per hour). In those conditions most personal vehicle drivers travel at about the same speed, so there’s less passing.
One point that doesn’t seem to get much attention is the fact that so many personal vehicles, and more recently tractors, have automatic transmissions. In a skid the transmissions in the later models of some personal vehicles at least, adjust to help control the vehicles. But I suspect that the older automatics, by continuing to power the vehicles, make it more difficult to steer out of a skid. The effect should be similar to staying in cruise control. And I do wonder whether the new artificial intelligence systems can brake vehicles into a skid in certain inopportune conditions.
I have found the manual transmissions in my cars and tractors to be valuable for the option to take the vehicles out of gear by depressing the clutch pedal and coasting to regain control in a skid. Late model trucks that I have driven with automatic transmission set to “eco” (green or economy) mode have freewheeled (coasted out of drive) when power was not needed, such as going downhill.
Another serious effect of bad weather is poor visibility such as in dense fog. I have had drivers draft me in fog in the apparent belief that I can see better than they and that I can “run interference” for them. In ground fog my angle of vision might be better than yours, but I make no guarantees. Especially in impaired vision conditions I advise hanging back and closely monitoring my truck to avoid rear ending it, should I have to slow down and/or stop suddenly.
Worse than “warm” fog is icy fog with an icy road surface. Obviously vehicle speeds have to be cut way down, and this condition may require a highway shutdown. In a large front of such weather I may park in a rest stop or truck stop to wait for clearing.
The worst driving is in a blizzard with snowy or icy road surface. In addition to treacherous traction, visibility can be reduced not only by the blowing snow but by ice buildup on my truck’s windshield in spite of its defroster. Visibility is also reduced by snow thrown up from other vehicles passing me or driving in front of me. I can sometimes drive through a localized stretch of such conditions before a highway gets shut down. However in an extensive storm front the highway is commonly shut down, sometimes for days if necessary to let the storm clear and get the highway plowed and de-iced and/or sanded.
I’m usually able to pierce a severe thunderstorm with wind (not tornadoes) and small hail stones at a faster speed than many personal vehicles. This is partly because my truck is heavier and less apt to hydroplane (though still vulnerable through large puddles). Also, from my higher vantage point I can usually see the road through the splash more clearly than personal vehicle drivers. Wind-blown dust and dust storms are other visibility hazards.
Passing Me in Bad Conditions
In all the bad weather and/or bad road conditions just described, it is wise to be aware of and allow for vision and performance limitations when deciding to pass my truck. In some cases you may elect not to pass or to wait until conditions improve. Passing on my left rather than my right is generally safer. When passing you will want to feel confident that given the road surface, you can maintain your stability and speed through any splash or blowback from my trailer and tractor wheels and not get trapped in one of the risk zones alongside me (see the Risk Zones chapter). Also be sure to allow more following distance behind my truck and increase the lead threshold beyond which you return to my lane (see the Passing Me Basics tip).
In very bad conditions on interstates or major highways with two or more lanes in one direction drivers of both trucks and personal vehicles tend to stay in line in the right lane with much less passing. Speeds may be reduced to 30 mph (miles per hour) or less. Understandably, drivers are even more reluctant to pass on two-lane highways. However some drivers, especially those in all-wheel drive vehicles, are evidently confident enough to pass anyway. If you do swing alongside my truck to pass, I will work to give you as much clearance as safely possible, even slowing down to let you by if necessary. In any bad weather I will have my truck lights on to be as visible as possible.
In winter there is one other reason to increase following distance, even in good weather and road conditions. Stay back when you see snow or ice on the top of a trailer in front of you. Chunks of snow or ice blowing off the top of a trailer can hit and damage your vehicle’s windshield or body if you are driving too close.
Trucks’ weight enables them to track more steadily than personal vehicles through rain water but not necessarily over snow or ice.
Be aware of factors affecting road surface conditions and chances of vehicle skids and spinouts, including air temperature, wind, types of snow and ice and presence of or lack of sunshine.
The best deterrent to skids and spinouts is always to slow down.
To recover from a skid, stay off the brake and steer in the direction of the skid until you regain control.
Increase your following distance behind a truck in bad weather and/or bad road conditions or if you see snow or ice on top of its trailer.
In bad weather and/or bad road conditions, allow for vision and performance limitations when deciding to pass a truck and be open to holding off until conditions improve.
When passing a truck in bad weather and/or bad road conditions, make sure you can maintain your stability and speed through any splash or blowback from the trailer and tractor wheels and not get trapped in one of the risk zones alongside it.