Winter driving is an important part of a professional truck driver’s life in Canada. Nothing prepares you for the nerve wrecking moment when a passing truck’s blowing snow completely obscures your view of the road, or when you’re driving through a whiteout and all sense of direction; right or left, up or down vanishes.
We are not attempting to frighten anyone, but this is what can happen in winter. You can prepare for it, but it’s not just the snow drifts and blackouts to be concerned about. Perils lurk in the shadows, even on bright sunny days, and in places that appear to be low-risk, such as parking lots and loading docks.
Visibility and traction are your two main concerns when driving in the winter. There will be times when you are desperately short of one or the other. You should try to avoid situations like that. You certainly do not want to put yourself in such a situation, but if it does occur, the key is to react properly and not to panic.
You can’t react to something you can’t see. Resist the urge to pull over if your forward vision is suddenly obscured by blizzard conditions. You could be the first vehicle involved in a dangerous chain reaction crash. A responsible professional truck driver, has already slowed down to account for the changing conditions.
In a whiteout, you will not be able to see traffic in front of you. In such situations, you must maintain awareness to know what’s ahead, even if it’s temporarily obscured from view.
Whiteouts are caused by passing trucks kicking up loose snow from the road, or by windy conditions causing streamers of snow to blow across open landscapes. Maintain your course and steer with caution. To help maintain your lane position, take a look at the road’s shoulder and gauge its position. Since everyone has a tendency to steer in the direction they’re looking, staring at the shoulder for an extended period of time can cause the truck to drift in that direction. As a lane position guide, glance rather than stare at the road’s edge.
A different approach is required for consistent blizzard conditions. Due to prolonged poor visibility, you must drive at a speed where your forward vision is at least equal to your stopping distance. Maintain your speed and course, and resist the urge to brake. You have no idea how the driver in front of you is reacting to the situation.
Staring into oncoming snowflakes can induce a state of hypnosis in which it is easy to fixate on the movement of the snow. Be aware that this is a possibility. Keep your eyes moving through your field of vision rather than staring straight ahead to avoid it.
If the poor visibility lasts more than a few seconds, gradually slow the truck down with a gentle brake application, just enough to turn on the brake lights. If the conditions are bad enough, any sudden changes in speed could result in a rear-end collision or a loss of traction.
Many truck drivers overestimate their traction in the winter, or they don’t realize what little traction they have. In most cases, deep snow isn’t an issue.
A tire tread that is too shallow, or low-rolling-resistance tires with naturally tight tread patterns and fairly shallow treads, is a threat to many off-road trucks. Tires work well on dry pavement, but they struggle on cold, hard, slippery surfaces like packed snow and ice. In most cases, getting the truck moving on slippery surfaces with such tires isn’t the biggest problem; the problem is maintaining traction during braking and directional control when steering.
Hard-packed snow is found on highways where tires repeatedly run over loose snow, compacting it into a hard, slippery surface. When the pavement is covered in hard-packed snow, the coefficient of friction changes dramatically. This normally rough surface texture of the pavement has been replaced by a smooth, slippery coating of what amounts to ice. There’s not much friction between the pavement and the tire tread.
If your tires are in poor condition, you are more likely to experience a lack of traction. On an icy surface, the worst-case scenario is an over-inflated tire with shallow tread.
The misbelief that anti-lock brakes (ABS) and electronic stability control (ESC) will save you a hard-braking scenario may elevate the problem. It is reckless to drive in a way that exceeds the capabilities of those systems.
The Jackknife Crash
Most trucks will have ABS and ESC as well. So, what makes them jackknife? The incident’s dynamics simply outweighed the systems’ ability to intervene. Are you willing to put your trust in those systems as a driver in those circumstances? You’d be much better off adjusting speed and following distances so that you never have to put it to the test.
The dynamics of a jackknife are simple to understand but may be difficult to grasp.
A free-rolling wheel will continue to move in the same direction. A non-rolling (skidding) wheel will respond to the crown of the pavement or any directional momentum in a curve. When a trailer skids, it is likely to begin sliding down the crown of the pavement or succumb to centrifugal force in the curve.
When a tractor skids, the situation changes. If the drive wheels locks up, the trailer’s momentum literally pushes the tractor out of the way. Because of its short wheelbase, the tractor quickly reverses until the side of the cab collides with the trailer, and the whole twisted mess careens forward until something stops it, such as another truck or a car.
There is little that can be done to correct the situation once the wheels lock up and begin to skid. The issue with ABS in these situations is that it frequently fails to react quickly enough. This is particularly true when a trailer is only lightly loaded. Alternatively, cold temperatures can cause the grease in the brake actuators at the wheels to become clogged. The brakes do not respond quickly enough to allow the wheels to regain traction. That is frequently a maintenance issue, not an ABS problem.
Appropriate Driver Actions
While understanding how jackknives occur is useful, the far more important lesson is to avoid situations where jackknives may occur. To put it another way, slow down and keep a safe following distance.
In this case, safe is a moving target. On clean and dry pavement, five to six seconds of following distance may be acceptable. On snowy roads, double the following distance you would use on dry and clean surfaces. This can sometimes become difficult because of other drivers cutting in and out. All you can do is step back and re-establish that safe distance.