What happens to your body in a crash?

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Road crashes are uncompromising affairs, which is why they kill such large numbers of people each year.

What really happens when you crash your car? Why do some people get badly injured – or worse – in a seemingly simple prang? David Washington takes a close look at the ugly anatomy of a road crash.

The hard truth: People are soft and cars are hard

Take a look around when you’re next in the driver’s seat. Think about your steering wheel, windscreen, windows, the dashboard and the pillar between the two side windows.

While 30 or 40 km/h seems slow in your car, that’s about the same speed that you travel when you’re going flat out on a bicycle.

Imagine a thick sheet of glass whacking you in the head at that speed.

Road crashes are uncompromising affairs, which is why they kill such large numbers of people each year.

What happens to you in a crash?

Crashes are all different and there are many different factors that can affect the severity of the injury – the kind of crash (rollover, head-on etc), the speed you’re driving at, whether you’ve got air bags, whether you’re wearing a seatbelt, whether you’re the passenger or driver, whether you hit a solid object or a car and much more.

Researchers at Monash University’s Accident Research Centre in Melbourne have been working with government departments, major car companies, insurers and others to collect masses of info about road crashes in Australia that have caused serious injuries to drivers and passengers.

They’ve looked at over 390 road crashes in fine detail and, while they’ve still got a lot more work to do, they have come up with some interesting facts and figures.

They have collected info on what parts of people’s bodies are injured in the different types of crashes and how the injury happened, right down to which bit of the car smacked into which bit of the body. Below is a summary of some of their work.

All crashes

Just under half of all crashes involved a vehicle hitting another vehicle, with the next biggest category being crashes into hard, immovable, narrow objects (poles and the like).

The severity of injuries was rated and the results are pretty scary. To put it in perspective, hospitals rate ‘major trauma’ as a score of 15 or above and the average score for these crashes was 14.6. Males tended to be more severely injured than females.

Head injuries were suffered by 39 per cent of people in the study, with severe injuries suffered by almost half of these. Two thirds of people suffered chest injuries and just under half of these were severe.

On average, the most severe injuries occurred in multiple-impact crashes where the car also rolled, and in side impact crashes.

The five bitter flavours of crashes

Stats show us exactly how people are crashing on the road. The top five crashes are listed below. Some are common in fatal crashes and some in minor crashes.

  1. The rear-ender

    The most common crash in Australia – it’s why tailgating is such a problem

  2. The side-on crash

    Otherwise known as getting “T-boned”

  3. The head-on

    Two cars whacking into each other – head to head

  4. Running off the road on a straight stretch

    This happens when people are speeding. Tiredness and distraction are also problems and this type of crash can also often occur when drivers swerve to miss something on the road. One third of all P plate crashes happen when there’s nobody else involved in the crash – just you, your car and something to hit

  5. Running off the road on a curve

    This is usually caused by going too fast, although being tired or getting distracted can also be factors. Unfortunately, you can encounter a range of immovable objects in this kind of crash – trees, electricity poles and more. And this is a big problem (see 'What happens to you in a crash' below).

Front-on crashes

The damage: Belted drivers and passengers typically suffered chest and lower limb injuries. Those not wearing seatbelts often had severe head and facial injuries and more severe damage to their chest and lower extremities (this includes the pelvis, legs and feet).

How does it happen? The severely injured crash victim typically hits the steering wheel and instrument panel. The study shows that injuries are far worse for those not wearing seatbelts.

Side-on crashes

The damage: Side-on crashes can cause serious injuries at relatively low speeds (an impact at 30 km/h can cause severe injuries). For people on the struck side of the vehicle, severe injuries were most commonly inflicted to the person’s chest, followed by the lower extremities, head and abdomen/pelvis (this means the contents of the pelvis – your insides). For people on the non-struck side, severe injuries were most commonly suffered to the head, followed by the chest.

How does it happen? On the struck side, severely injured people are most commonly hit by the door panel. For non-struck side occupants, severely injured people most commonly hit the driver or person next to them and then the “B pillar” on the rebound – the upright pillar immediately behind the front door, where the seatbelt is anchored.

Rear crashes

The damage: Severe injuries were most commonly suffered to the chest, head, neck and spine.

How does it happen? People are severely injured by the whiplash effect – whiplash is thought to result from the movement of the head forwards and then backwards very quickly.

Multiple impacts and rollovers

The damage: When a vehicle hits more than one other vehicle or object, or when it rolls over, the damage can be severe. The highest proportion of these crashes in the study involved a vehicle rolling over and then hitting a tree, or hitting a tree and then rolling over.

Rollovers most commonly caused severe injuries to the upper extremities followed by the chest. Head and face injuries were also common. In multiple-impact crashes, the most severely injured people commonly had upper (hands, arms and shoulders) and lower extremity injuries, followed by chest, abdomen/pelvis, and head and face injuries.

How does it happen? In straight forward rollovers (not hitting anything else), people are most commonly injured by hitting the doors and the roof. People are also hurt when their body is ejected from the vehicle. In rollovers where the car hits something, people are commonly injured by the door, the floor, an object other than their car and the steering wheel. You get the picture that if you’re not wearing a seatbelt you would be tossed around helplessly inside the car. For multiple-impact crashes, severe injuries are most commonly caused by the person hitting the instrument panel, followed by the door.

Bottom line

People injured in road crashes often end up in hospital, with a lengthy rehabilitation ahead of them and some people never fully recover. Of course, many people don’t survive.

Wearing a seatbelt is the simplest and most effective way to reduce the risk of injury in front-on crashes and many other types of crashes. There are other safety devices, such as airbags, that can also reduce the severity of injuries in a crash, while others, such as electronic stability control – or ‘ESC’ – can actually reduce the possibility of a crash occurring.

The truth is that most crashes can be avoided altogether through safe driving.

More info

The research in this article is from the Australian National Crash In-depth Study (ANCIS). The study aims to establish the causes and mechanisms of injuries in real-world crashes through in-depth crash investigations. The ultimate aim is the design of safer vehicles for Australian roads. For more information go to the Monash University Accident Research Centre website.