Black ice warning

It’s that time of year when alpine enthusiasts are heading off on their annual snow holidays, relishing the thoughts of a few remote, high-altitude weeks away from civilization.

As it’s an annual thing for many, proper car preparation for a below-freezing alpine experience is a given: Not just the car itself, but the snow-road assistance systems such as tyre chains that are mandatory in most places as well as a good knowledge of how to handle a vehicle safely in ice and snow.

But winter driving is not exclusive to just the alpine regions. Everyday drivers can get to experience it too – the big difference being that the experience can often be an unexpected one.

And that makes it not only challenging, but often downright dangerous as road conditions deteriorate from being merely wet and slippery to slick and icy, offering virtually no traction whosoever.

This means a disconnection not only from the car’s wheels in terms of accelerating or braking, but also from the steering.

In such circumstances, the vehicle becomes a projectile completely uncontrollable by the driver. Even at lower speeds, the car will go where its forward momentum takes it. If it’s on a corner, it will tend to go straight forward off the road or into the path of oncoming traffic. If it’s on a slope, it will want to simply head downhill.

It’s not unlike aquaplaning on a sheet of water that is covering the road surface, except it’s even less forgiving and there’s often little or no warning allowing the driver to take preventative or corrective measures.

In northern Europe and in the USA, slick winter roads are a familiar hazard and people tend to be generally ready for them. Drivers get to regularly experience driving on ice or snow and usually prepare themselves (driving practices), and their vehicles (type and condition of tyres), accordingly.

But that’s not the case in most parts of Australia. Blocky-tread winter tyres (not blocky-tread 4WD tyres) for regular cars are no longer common, tyre chains are only used in alpine areas and steel-studded tyres, which are often used in extreme winter conditions elsewhere around the globe, are unknown.

As for driver awareness, that’s pretty limited too. Particularly in areas where road ice doesn’t occur frequently, drivers rarely have the potential hazards in their consciousness. That is behind the vehicles often spotted in roadside ditches on especially cold mornings or, more distressingly, the seemingly inexplicable vehicle-to-vehicle collisions on curving roads in similar circumstances.

A sheet of ice covering the road drastically reduces friction, and the ability of the driver to steer or stop the car. The stopping distance from speed on an icy surface, for example, has been measured at about four times that required on normal, dry pavement. Manoeuvrability is affected similarly.

Most insidious of all is the phenomenon of black ice, in which the road surface is covered invisibly by a thin patina of transparent – not opaque – ice. Because it doesn’t trigger alarm signals in the same way as a visibly icy white surface, it is able to catch-out the most wary driver.

According to statistics from Sweden, car accidents are five times greater on roads covered with black ice than on dry roads. They are four times higher than on wet roads and twice as high as on roads covered with packed snow.

Black ice forms similarly to visible ice, except that the layer could be described as more “pure” because it doesn’t contain disturbances such as tiny bubbles, particles or other imperfections. It forms in a number of ways, but generally comes about as a thin layer of water freezes overnight to form an invisible skating rink. It is prevalent in the early morning and, later, in shady patches of road under trees or bridges that are delayed in receiving the benefits of the sun’s warming rays.

So what can the average driver, who is neither familiar with, nor is equipped with ways of dealing with what can be a seriously dangerous phenomenon?

There are two basic rules. One is that, where possible, a driver planning an early morning excursion on a freezing morning should be acquainted with exactly what conditions are prevailing. In some parts, warning signs and lights are installed to warn of ice danger (many new cars also have an ice warning that flashes on the instrument panel at low temperatures to alert the driver of possible risk). The second is that, if you can’t avoid being out there on a super-cold morning, you should adjust your driving accordingly.

The message is: Drive slowly, and be aware of other traffic around you – especially of the idiot approaching at speed from behind. If the road feels so slippery that even slow speeds don’t give full control, simply abort the effort and only resume when full traction is available. And, even when it is apparent that the sun has melted the ice and rendered the road surface safe, beware those shady patches where it may still be in its frozen state. As well as the trees and under-bridge locations mentioned earlier, older-style bridges with wooden surfaces are known for their lack of traction in icy – or simply wet – conditions too.

If you do hit black ice unexpectedly, there are a number of things to remember: One is that you should keep the steering wheel straight and, second, you should avoid hitting the brakes. Lift your foot off the accelerator to slow down.

Typically black ice covers a limited area – say around six metres – so if you can keep your vehicle travelling in its initial direction you stand a chance of regaining traction on the non-icy surface relatively quickly. Even then you should steer and brake with caution.

And SUV drivers can’t necessarily take solace in the extra traction provided by their all-wheel drive systems. Stopping distances and cornering abilities will not be a lot different to those of a two wheel drive vehicle, although the ability to power off from standing start might benefit a little from the fact all wheels, not just two, are providing the motivation. “Powering off” might be a slight exaggeration however.

While we are on the subject of cold mornings, it’s probably timely to give a little comfort to those who don’t have the benefit of an overnight garage and are confronted on the odd cold morning with a large chunk of ice that only resembles the profile of a car.

The problem is not centred on how you are going to heat the thing up enough to make it habitable, but how you are going to see what is around you through the ice-encrusted glass.

There are a number of methods that can be employed, from the dousing of the windscreen, side and rear windows with water to dragging a credit card out of your wallet and setting it to work as a glass scraper.

Our preferred method is the credit card but, whichever you use, you are advised to leave the demisting system at full bore until the engine has warmed sufficiently  to clear away the internal misting that renders the outside world virtually invisible from the driver’s seat.

For safety’s sake it is best to be patient and let this process occur until 360 degree vision is restored. At the very least, even if the windscreen is clear and enables you to proceed safely, it is a good idea to brave the freeze and lower the front side windows to allow unimpaired side vision as you approach intersections.

Admittedly icy road hazards are experienced more commonly in the southern parts of the country, but higher altitudes further north can induce the odd unexpected cold snap with the accompanying safety risks.

Black ice is out there. Don’t be lured into a false sense of security on cold mornings even when the road surface looks perfectly harmless. It may be just the opposite.