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How The Car You Drive Affects Your Safety

Your and other drivers’ behaviour is the most important factor in your safety on the road, with the majority of fatal car accidents in Australia caused by avoidable driving behaviours like speedingdriver fatiguemobile phone distraction, drunk driving and reckless cornering.

However, once a collision is inevitable, the safety features in your car become the most important factor in either limiting or amplifying the severity of the accident. Awareness of the importance of car safety features when buying a car is therefore a critical component of road safety.

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The impact of car safety features on the Australian road toll

Road fatalities per 100,000 population in Australia have decreased by around 80% since 1975. This is partly a result of efforts by public authorities to raise awareness of dangerous driving behaviours and pass legislation that is effective in preventing these behaviours.

However, the influence improved car safety features have had on the Australian road toll over the last several decades is apparent in the fact that the number of people per 100,000 population that are being hospitalized after car crashes is increasing steadily. More people are being hospitalised for, and surviving, accidents that would previously have been fatal.

The car safety features that matter

No single car safety feature affects accident outcomes. Instead driver safety is most effectively enhanced when safety features work in combination to limit the risk of collision, the impact speed at the point of collision and finally the extent to which impact forces are transferred to car occupants.

Car safety features are divided into two categories:

  • Safety features which act to prevent an collision happening in the first place, which are described as active safety features.
  • Car features designed to protect occupants once a collision takes place, which are known as passive safety features.

In the following section we consider optional active and passive car features that can considerably improve your safety on the road. Note that we do not include features such as anti-lock braking systems (ABS) or standard electronic stability control (ESC) systems, which are now standard features in new cars.

Active safety features

The majority of advances in car safety over the last couple of decades have taken place in the field of active safety features. This has been driven by technological advances which have made it possible for vehicle systems to independently respond to a variety of potentially hazardous situations. These systems are intended to prevent an accident taking place, or to reduce the severity of the accident if it is inevitable.

Brake assist systems

Brake assist is designed to ensure optimal performance of the antilock braking systems (ABS) that are standard in modern cars. The effectiveness of ABS systems is highly dependent on driver behaviour at the moment of impact, and ABS can actually deter drivers from applying brakes with full force due to the unusual pulsing feedback the brake pedal may generate when fully engaged.

Brake assist systems are able to detect panic braking and automatically brake with maximum force, taking subsequent driver response out the equation. When combined with ABS brakes this prevents the wheels from locking up while ensuring the shortest possible stopping distance on dry and wet roads (stopping distances will actually increase on gravel roads when ABS brakes are engaged).

Autonomous braking systems

Autonomous braking systems are designed to take driver error out of braking entirely. If your car is equipped with one of these systems it will be able to detect imminent collisions and independently activate your braking system to prevent these. While this new technology is not cheap, it can substantially reduce the risk of collision in a wide variety of hazardous situations.

Tyre pressure monitors

Tyre pressure monitors are probably the most inexpensive and effective optional safety feature you can add to your car. These monitor tyre pressure and alert drivers as soon as tyres are either over- or under-inflated. This in turn allows drivers to maintain the correct tyre pressure and promptly address punctures. This in turn improves tyre performance while cornering or braking.

Passive safety features

Advances in passive safety features are progressing more slowly than active safety features. Many critical passive safety features may also not be advertised by car manufacturers, and their presence or effectiveness is instead implied in their ANCAP ratings. Because some accidents are unavoidable, these features should not be underestimated, and can make the difference between life and death.

Car body shell

The strength of the shell surrounding car occupants plays a major role in accident outcomes. Flimsy cars will typically experience partial or total collapse of the cabin area during collisions, and it is not unusual for the engine block to be forced into the interior of the vehicle during frontal impacts. This means that some cars become deadly in even low speed collisions, while well-built vehicles can provide car occupants with significant protection even in severe accidents.

The best way to gauge the quality of your car’s build is to review its ANCAP safety ratings and any crash test videos available online.

Crumple zones

While a car’s car cabin shell must provide structural strength to prevent it from crumpling inward on car occupants, other parts of the chassis play a critical role in absorbing the force of collisions. Crumple zones are areas of a car designed to crumple in response to impact forces. The deformation of these areas soaks up energy and force that would otherwise be applied to car occupants.

A safe car will combine with a very strong body shell with carefully engineered crumple zones. This ensures that collision forces are reduced before they are transferred to the passenger cabin, and that this cabin is also structurally able to resist the residual forces applied to it during an accident.

The seatbelt

While seatbelts are a non-optional feature of any car, older car models may be equipped with outdated seatbelt systems missing important seatbelt safety advances, including:

  • pre-tensioners that reduce seatbelt slack at the moment of frontal impacts
  • load limiters which allow a slight stretch in the seatbelt during collision to prevent the seatbelt from causing pressure injuries to occupants’ torsos
  • adjustable upper anchors, which allow car occupants to move belts away from their necks and onto their shoulders.

While preferable to wearing no seatbelt, outdated seatbelts increase the risk of injury or death in an accident compared to modern seatbelts. Before purchasing a vehicle it’s therefore worth checking if your vehicle is equipped with all three of the modern seatbelt safety features listed above.

Head restraints

Head restraints are probably the last thing that most people worry about when choosing a car. However, these are a critical safety feature in the event of collisions from the rear. A car’s head restraint should be fully adjustable, allowing the driver to raise it to match the level of their head, and to tilt it inward so that the head is not located more than an inch away it. You can easily check how effective your car’s head restraints are by checking how the car performed in this department during ANCAP testing.

Side airbags

Airbags can substantially reduce the risk of serious injury in car accidents – if they are properly maintained and used in conjunction with seatbelts and appropriate positioning of child seats.

Front airbags are now standard on most vehicles. However, curtain and side airbags are not standard on many vehicle, particularly in the passenger compartment. This is problematic because of the high number of T-bone, intersection and rollover accidents that take place every year, which can easily result in severe injuries to the heads and sides of car occupants at low speeds.

It is advisable to have both side and curtain airbags in your car. Side airbags should extend along the length of the entire cabin, protecting occupants’ torsos during side collisions. Curtain airbags will provide head protection during side and rollover accidents. Both can protect car occupants from airborne debris generated during the collision.

Roll cages and roll bars

Rollover accidents  are known to be particularly lethal. This is because many cars provide little structural resistance to forces applied to the roof or its support columns. Which means car roofs tend to collapse into the cabin during rolling accidents, resulting in serious head injuries.

Roll cages are designed to provide vertical structural support during rollover accidents, but are rarely available in mass production vehicles. Roll bars are a simpler solution that are commonly seen on utes and convertibles– these provide basic rollover protection in the event of a rollover accident. Some models of vehicle are equipped with active rollover hoops which extend and lock into place once the system detects the a car is tipping over.

The importance and effectiveness of these systems is demonstrated in professional car racing, where the majority of vehicles are fitted with rollover bars or cages to improve driver safety.

Low centre of gravity

Your car’s centre of gravity has a major influence on how it will handle cornering, or respond to side impacts. The higher the centre of gravity the lower the force required to tip a car over when it corners recklessly or experiences a side impact.

The centre of gravity will roughly correlate with your vehicles ground clearance and total height. The higher off the ground your chassis is, the higher its centre of gravity is likely to be. This is problematic because a lower centre of gravity is not advertised as a safety feature, whereas increased ground clearance and vehicle size are both actively marketed as being attractive.

When buying a taller, more narrow vehicle, be aware that the risk of rolling is increased. Auto-manufacturers are aware of this risk, which means this type of vehicle may be equipped with additional safety features that are designed to stabilize the vehicle – such as active rollover systems and tyres that offer less traction to avoid the build-up of centrifugal forces while cornering.

A cheaper and more effective way to lower a car’s risk of rolling and its centre of gravity simultaneously, is to simply buy a car that is shorter and has less ground clearance. Many sports car models and hot hatches are designed with lower centres of gravity, leaving you to worry about the less hazardous risks of scraping your bumper on the pavement while parking.

If you insist on buying a car with ground clearance, it’s worth doing some research on how it shapes up in rollover statistics. Not all SUVs have the same roll-prevention features, and some have a greater tendency to become involved in rollover accidents.

ANCAP ratings

ANCAP ratings offer a summary of the effectiveness of many of the passive safety features we have discussed. While the overall ANCAP rating is a useful indicator of how safe a car is, it is worth digging deeper into the ratings a vehicle achieved on each part of the test to get a true idea of how it will handle typical collision scenarios.

These include:

  • frontal offset collisions
  • side impacts
  • side pole collisions.

The following systems are also considered in the rating:

  • whiplash protection
  • airbag systems

Buying a vehicle with a 5 star ANCAP rating is not a frivolous expense. It the single biggest investment you can make in your safety in the event of an accident.

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