Slush – a sloppy mixture of snow, ice crystals, water, dirt and, on most of our roads, salt or some other de-icing agent makes for some of the most dangerous winter driving conditions we encounter in Canada.
It's particularly prevalent when the temperature hovers around freezing and snowfalls are heavy and wet but because of the road salt often involved it can also exist at much lower temperatures. It also has a tendency to build up between driving lanes and between the wheel tracks within a lane, creating a barrier against lane changes.
There are two challenges when driving in slush
- Slush typically has the friction characteristics of wet ice – which is to say not much at all – and that means tires have very limited traction for accelerating braking or turning.
- Because it tends to build up in mounds and winrows it acts as an obstruction against the sides of the tires when turning, as well as creating a slippery surface for the tire treads.
It's that side-force that often catches drivers out, especially when changing lanes with slush banks between them. If the driver turns too sharply into the built-up slush it provides a sudden and significant resistance – like applying the brakes on just the front wheels. With limited traction at the rear wheels, a braking force applied at the front and the vehicle beginning to turn, its natural tendency is to keep on turning.
Often, the driver's reaction in those circumstances is to lift off on the accelerator, which applies an additional engine braking force on the front wheels of front-wheel-drive vehicles, further amplifying the problem. This frequently results in a spin-out.
Here are some tips to avoid spinning out when driving in slush
- Don't change lanes through slush rows unless you have to.
- Plan your lane change and choose a spot where the slush is the least dense.
- Turn the steering wheel slowly and gradually so you approach the slush at a shallow angle, minimizing the force against the side of the tires.
- Maintain a loose but firm grip on the steering wheel so it won't change position when the tires hit the slush and keep steering in the direction you want to go.
- Maintain a steady pressure on the accelerator pedal so as not to induce either a braking or accelerating force at the tires. Bring the steering wheel slowly and smoothly back to straight ahead when the lane change is complete.
If you absolutely have to change lanes in slushy conditions, smooth and steady is the key to doing so safely.