Fatal impact of reckless cornering

The Fatal Impact of Reckless Cornering

What is reckless cornering?

The forces experienced by a vehicle while cornering will to some extent depend on the type of vehicle being driven, and what is dangerous will vary slightly between motorcycles, cars, vehicles towing trailers and larger vehicles like trucks. For the purposes of this discussion we’ll therefore consider dangerous cornering from the perspective of car drivers.

Reckless cornering in a car can involve one or more of:

  • cornering without considering potential obstacles or hazards hidden by the bend
  • accelerating or braking while cornering
  • changing gear manually while in a corner (thereby removing a hand from the steering wheel)
  • maintaining inappropriate speed through a corner
  • crossing lane markers while cornering
  • sharp cornering – making a substantial sudden or late change in a car’s direction using the car’s steering.

Typically these dangerous cornering habits will take place in combination. For example, drivers maintaining high speed into a corner are usually required to make sudden changes to car direction when encountering sharp bends.

Why reckless cornering is dangerous

Cornering can potentially challenge a car’s stability and safety systems, as well as driver ability, more than any other driving activity. This is because a number of factors and physical forces impact a car while cornering, and combine to determine whether or not the car will navigate the corner safely.

Reduced visibility

You don’t need a good grasp of physics to understand the primary risk associated with corners. Unless you’re driving on a flat, featureless landscape, any corner poses an obvious and immediate problem – you can’t see around it. Therefore any behaviour that reduces your response time while cornering leaves you exposed to a virtually endless variety of sudden, unexpected road hazards that might be lurking out of sight around the bend. For example, a car that has stalled in your lane.

Centrifugal forces

As soon as a car goes into a bend, centrifugal force starts to act on it. You can picture this force as one that resists the car’s turning motion by pushing the car sideways towards the edge of the curve it is taking. This force is rapidly strengthened by increases in a vehicle’s speed and mass, as well as by decreases in the radius of the corner (i.e. tighter turns).

The primary parts of your car counteracting centrifugal forces while cornering are your tyres, which produce what is known as centripetal force, or ‘cornering force’. When the centrifugal force exceeds the cornering force of your car’s tyres, your vehicle will lose traction with the road and you will typically lose control of it as it departs the curve.

Inertia

Centrifugal forces don’t act alone. When your vehicle takes a corner it also experiences a force of inertia – physical resistance to a change in direction.

Like centrifugal force, inertia will push your car towards the edge of the curve.  However, unlike centrifugal force, which is applied to your tyres at ground level, inertia acts on your vehicle’s center of mass, which is usually higher off the ground. The effect of these forces in combination is to tilt your car in the direction of the curve, a movement which is called a vehicle’s ‘roll’.

Two things counteract these combined forces – gravity and your car’s suspension. Your suspension is designed to generate equal and opposite force to the rolling force, effectively redirecting the force of the roll back onto the tyres on the opposite side of your car. In addition, gravity takes your side by providing an anchoring force on your inside tyres.

As long as your suspension and gravity are able to balance inertia and centrifugal force your car will not roll over. However, the faster and harder you corner, the more these forces increase. At some point they will meet and exceed your car’s ability to counteract them and it will roll over.

Traction

Friction between tyres and the road surface is required to accelerate, stop or turn a car. You probably understand this intuitively already, and realize the importance of reducing your car’s speed in any conditions that reduce road friction, such as muddy, wet or icy roads.

Every set of tyres has a maximum amount of friction it can generate with a road surface, and turning, accelerating and stopping all push a tyre towards this friction limit.

The moment you drive your car into a corner you immediately take a step towards your tyres friction limit. Once in the corner any additional work the tyres do reduces their capacity to supply the friction required to navigate the corner safely.

Once the friction limit is reached on a tyre it will lose traction with the road and the driver will partially or completely lose control of the vehicle’s steering, acceleration and braking systems.

The deadly effects of reckless cornering

Accidents involving reckless cornering will typically involve one or more of the following scenarios:

  1. loss of control of the vehicle
  2. departure from the road
  3. rolling the vehicle.

The danger here is, of course, that a road is by default a surface cleared of fixed obstacles. In contrast, the side of the road is packed with obstacles ranging from trees to traffic lights, lampposts, walls and pedestrians. Therefore once a car departs a curve there is an extremely high probability it will collide with an obstacle of some kind.

At this point the loss of vehicle control comes into play, as a panicked driver will usually be unable to effectively brake the car – or steer it away from a collision with an obstacle. In a best case scenario all four wheels will make contact with a high friction roadside surface and bring the car to a halt. In a worst case scenario the driver will impact an obstacle without being able to slow the vehicle.

And the higher the speed at point of impact the greater the risk of serious injury or death, with the lethality of impacts at 50km/h hour or above increasing rapidly for every 5 km/h increase in speed.

Rollovers

If centrifugal and inertia forces overpower the car’s suspension system while cornering, this will result in an ‘untripped’ rolling accident. Alternatively, while departing the curb the curb side of a car may strike the curb or hit softer ground. This will cause a sudden increase in horizontal force which will overpower the car’s ability to resist these forces, causing a ‘tripped’ rollover accident.

Whether tripped or untripped, rolling accidents are the most dangerous of all accident types.

This is because most cars are not equipped with roll cages or rollover bars. In simple terms this means that the car provides little, if any, structural resistance to the roof crumpling into the vehicle’s cabin on impact with the ground. Therefore car occupants will usually sustain severe head injuries from contact with the collapsing roof or road surface.

Reckless cornering fatality statistics in Australia

Australian states don’t record reckless cornering as a behavioural cause of accidents. However, New South Wales, Western Australia and Victoria all record and report data on accidents that occur on or around corners or curves.

The following table presents the number of fatalities recorded for these accidents as a percentage of road fatalities for the relevant year, where data is available.

 20122013201420152016Avg
NSW122%27%22%25%22%24%
VIC28%11%9%10%14%11%
WA328%24%27%28%27%

1NSW fatalities recorded as “Off path or out of control on curb”. 2VIC fatalities recorded under “Run off road on a curb”. 3WA fatalities recorded as “Accidents on curves”.

While there are minor inter-state differences in how this type of accident is categorised, this data provides the clearest available picture of fatalities caused by cornering in Australia. When the fatalities caused by cornering accidents is considered in terms of the combined road toll for these states, these account for 20% of road fatalities.

This figure is in the same range as some of the heavyweights of the ‘fatal five’, including speedingdriver fatigue, and driver inattention

Once you are aware of the risks associated with cornering, the next step towards safer driving is to improve your driving and observation skills when navigating corners. You’ll also need to ensure that your car’s suspension and tyres are in good condition at all times.

You can improve your safety when cornering by taking the following steps:

Give yourself enough space to brake

When taking a corner you need to be aware of how far ahead into the corner you can see, and consider the possibility that a stationary object may be just outside your field of vision.

You should then assess whether or not you’re maintaining a speed low enough to come to a stop before you reach the point where the corner bends out of sight without having to slam on the brakes. If you feel like you’d be unable to stop your car completely without emergency braking before reaching that point, then you’re going too fast.

Brake before you hit the curve

As explained in the section on traction, you want to avoid asking your tyres to do extra work when cornering, since they are already working hard to stop your car being pushed off the curve by centrifugal force.

What this means in practice is that you want to avoid any braking once in a corner, with the exception of braking your car to prevent a collision. Instead you want to reduce your speed to the appropriate level before turning into the corner.

Don’t accelerate out of a bend

Accelerate only once your tyres have been straightened and your car is travelling a straight path. This will also help you to avoid changing gear while you are taking the corner.

This recommendation excludes turns into corners from a stop, such as at four way stops, where accelerating your vehicle is unavoidable. In these situations accelerate gently, and only make substantial increases to your car’s speed once your steering and wheels have been straightened.

Use lanes appropriately

Assuming you’re driving on the left hand side of the road, you want to:

  1. Be closer to the lane dividing line while taking a left turn. This requires less steering correction while taking the bend and generates less centrifugal force. However, be aware that driving too close to the lane divider puts you at risk of colliding with oncoming drivers who are taking a right turn inappropriately and crossing into your lane. So allow sufficient space to compensate for oncoming drivers wandering into your lane.
  2. Drive closer to the outside lane when taking a right turn. This requires less steering correction into right turns and reduces the relevant centrifugal forces. It also prevents you from coming into close proximity with oncoming drivers who might cross the lane dividing line. However, be aware of your proximity to the curb and allow for some space between your curb-side tyres and the edge of the road, as you are also narrowing the margin for your car coming off the road if other behaviours or conditions put you at risk of losing control of your vehicle.

Adhere to speed limits where possible

If you’re unsure at what speed to take a corner, observe any speed limit posted near the entrance to the corner. Where corners are indicated by road signage, or where the corner clearly has a small radius, lower your speed in proportion to the sharpness of the bend.

Maintain your cars tyres and suspension

Your tyres and suspension are the two main systems your car requires to generate traction and push back against centrifugal and inertia forces. Therefore anything that impacts their performance will also impact your car’s ability to safely navigate turns, and lower the threshold at which things can go wrong. Ensure your tyres are inflated to the correct pressure and have sufficient tread. Also have your suspension checked and serviced at the recommended intervals.

Install UbiCar on your phone

It’s tough to know how well you are cornering, even if you are trying to do the right thing. Telematics apps like UbiCar can be a great help in assisting you find out how well you corner, as well as when and where you are making mistakes.

Download UbiCar now to find out how well you corner, and we’ll also show you how we reward smart drivers.

Get fairer car insurance. Based on how you drive

1. Crossover trim

Don’t have the money to buy yourself a 4×4? Don’t worry, auto manufacturers can help you dress up your car so that the average person won’t be able to tell the difference. You can elevate your suspension, get faux roof racks fitted, put mud guards over your tyres and do all sorts of other things that will do little to compensate for the fact that your car is, in fact, a front wheel drive with a one litre engine. If you’re offered this kind of trim, turn it down. It costs money, accomplishes nothing and adds little, if any, resale value to your car.

2. Racing trim

Racing trim can include anything from rear spoilers to custom sports rims on your car. While this kind of trim can make your car look like a mean machine, it’s once again about style rather than substance. And to make matters worse, the more of this stuff you add the more the pool of potential buyers dwindles. When it comes to racing trim remember that less is more, and that whatever you invest in it won’t be returned when you sell the car.

3. Tinted windows

Nothing says ‘I’m definitely not trying to sell crystal meth’ to the local constabulary like heavily tinted windows. Unless you have some practical, pressing need to make yourself invisible while behind the wheel, and don’t mind being pulled over more frequently than more transparent drivers, skip the dark tints. Dark tints not only don’t add value to your car, they can actually make it difficult to sell for its book value in future.

4. Enhanced audio systems

If you feel the need to share your favourite track with everyone in a five block radius, then chances are you’ll want to get your car a supercharged sound system. The problem with these systems is they can cost a fortune but have little impact on your car’s value. However, if you do want to jack up your sound system, go with the manufacturer options. Highly customized sound systems can interfere with your car’s factory systems and settings and lower its resale value.

5. Keyless entry and ignition

Keyless systems are finding their way into an ever-increasing number of cars, and are typically offered as an optional add-on when buyers are customizing new cars prior to purchase. This type of convenience says ‘premium’ but will save you about five calories of effort every day. And when the time comes to sell your car, the person you’re thinking of selling it to probably won’t see freedom from the tyranny of keys as any sort of meaningful benefit and is unlikely to pay extra for it.

6. Special paint jobs

Many auto manufacturers charge extra for cars in certain colours and finishes. Typically the colours involved here are the type that make your car stand out more. Which means they’re the same type of colours that will put off the majority of second hand car buyers. Special paint jobs and finishes can add as much as 10% onto the sales price of your car without increasing its value whatsoever. So stick with the standard factory colours and finishes. And don’t be tempted to add racing decals or custom spray-paint jobs to your cars unless you have no intention of selling it at book value.

7. Out-of-league trim

There’s a certain logic to buying an entry level, cheap vehicle and then attempting to convert it into a luxury vehicle by adding leather seats, electric windows, a sunroof and larger wheels. This can provide you with a more pleasurable driving experience, but the only effect it’s likely to have on the car’s book value is to decrease it. That’s because the greater the deviation from the factory standard, the less likely someone is to buy your car, even if it has plush finishes. Conversely, and unfairly, if you buy a luxury car without many of these features, it’s likely to lose resale value.

8. Telematics tracking devices

You may decide to install a telematics tracking device in your car to ensure it can be tracked in the event of vehicle theft, or used to generate lower insurance premiums. While these are good reasons to use tracking technology, just bear in mind that you’ll absorb the costs associated with this, as telematics devices add no value to your car in the resale market.

Instead consider that there are also solutions on the market that turn your smartphone into a powerful telematics device for free.

UbiCar is a smartphone-based telematics car tracking solution that rewards smarter drivers. Download UbiCar now to find out how it can reward you for good driving.

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