When car experts, engineers and mechanics talk about car accidents and collisions, they often mention the crumple zone of a vehicle. Although the car crumple zone is one of the essential parts of car design, many drivers are not aware of its existence or role, or they often do not realise how important it is for driving safety. 

This article explains what car crumple zones are, why they matter, how they work and why they can be a real life saviour in the case of an accident. 

What is a crumple zone of a car? 

The crumple zone, also known as crush zone or crash zone is a special structural area in the front and sometimes in the rear of a car. As the names imply, it is designed to crumple in the case of an accident

car with crashed frontAn example of a crumple zone keeping the passenger cell safe in a collision.

More specifically, it is fairer to say that it is the car that is meant to be crumpled in a controlled way as the crumple zone absorbs the impact energy of the collision. This prevents the force from immediately and directly affecting people inside the vehicle. Thanks to crumple zones, the overall safety of the driver and passengers is greatly improved.

The beginnings of crumple zones

The very first crumple zone was designed in 1959 as a result of the idea of Béla Barényi, an Austrian-Hungarian engineer employed by Daimler-Benz, now known as Mercedes-Benz or Mercedes. 

As far as vehicles are concerned, one of the earliest car models to include a crush zone as a safety feature of the design was the 1953 Mercedes Ponton or W120. The patent itself, however, was granted in 1952, and the first car to feature this specific design was the Mercedes W111 in 1959.

How do crumple zones work?

While the design of a car crumple zone and implementation techniques have changed over the years, the concept behind Béla Barényi initial idea has not. Barényi wanted to see if certain parts of the vehicle - specifically, the front and rear, could be built in a way which would enable it to absorb kinetic energy.

Consequently, the midsection of the car is often referred to as the passenger cell or safety cell. This is the area that the crumple zones physics serve to protect.

Test car hitting tree

Why is this so important during a crash? Any sudden act of braking or stopping typically causes a wave of kinetic energy. In the case of collisions, this wave of energy may push parts of a car and objects, such as walls and other vehicles, into your car, risking harm to you and your passengers. The crushzone serves to absorb this energy, preventing harm to the passenger cell as much as possible.

The construction of a crush zone 

Originally, crumple zone design was based on longitudinal components. The construction of the front and rear ends of the vehicle included supports that were curved to encourage a certain kind of physical deformation, instead of transferring the full kinetic energy of a collision into the safety cell.

Further designs also included additional ribs, installed both horizontally and vertically, to help create a shock-absorbing ‘cage’ around the passenger cell. In this way, chances are that any potentially remaining energy that does not get absorbed can be redistributed, preventing significant energy build-ups.

Currently, the most commonly used crumple zone materials are especially-engineered metals, plastics and plastic composites. These help to keep the car lightweight while providing the right amount of impact resistance so that the crumple zone can work properly.

How do crumple zones affect the car?

Knowing how crumple zones work, you are surely aware that they take on a lot of damage. In many cases, this damage is unrepairable. Obviously, though, it is better to replace your car then suffer extensive injuries during a collision. 

Front view of crashed carDepending on the force of the impact, the damage can sometimes be repaired.

In many ways, you could consider the crumple zone to be similar to the suspension system. Naturally, the major similarity is that it absorbs forces that could affect other car parts and you don’t want to disturb the rest of the vehicle. 

Remember, however, that there is a crucial difference between how the suspension system and crash zones influence the car. While enough shocks and potholes can damage your suspension, a crumple zone isn’t designed to resist impact after impact.

Naturally, many drivers are concerned about their engine, which is typically placed in the front of the vehicle. However, the crumple zone is based around a mixture of parts that do and do not resist the force of the impact, using the latter as a final layer of protection. Engines fall into this category as their hard, durable design does not bend easily, making them very resistant and useful absorbers. Since they are not actively involved, in most cases, your car wheels and tyres will also remain unaffected.

After a collision, the chances to get the car repaired depends on both the force of the impact and the design of the safety system. Large steel or aluminium parts, such as the engine and framework, are designed to withhold any damage, while other parts are designed to crumple and these will typically need to be replaced. As a result, while the crumple zone may very well keep you safe from harm, it does not guarantee the car will remain in a drivable state.

Cars on road after accident

In extreme cases, when the bodywork is severely damaged and even the engine and framework have been unable to resist the complete impact, the car might be impossible to repair.

Crumple zones in motorsports

Needless to say, crumple zones are particularly important in motorsports. This well thought-out and carefully manufactured design of such a system has saved numerous drivers’ lives. Crumple zones are vital as high impact collisions with great kinetic forces are very frequent in motorsports due to the competitive nature of racing and higher speeds.

Similarly, throughout racing history, there have been attempts to decrease the impact from the track itself. While car-to-car collisions can’t be affected, tracks have different forms of extra protection such as foam padding or old tyres around walls and corners of the track. The idea here is that these softer materials will help to further lessen the blow, acting like a cushion and passing less energy onto the crumple zone in the first place.

Formula 1Motorsports, such as Formula 1, actively use softer border materials and open spaces to help lessen the impact.

This is also why, wherever possible, corners usually have large open expanses of rough terrain before the barrier. In the case of steering out or something else going wrong, this terrain, unlike smooth tarmac, will offer rolling resistance, helping to slow the vehicle down before the impact force hits. 

Improved road safety

Basically, the crumple zone is a built-in safety feature in all modern car designs and is not something you can choose or change. It may differ across various car models but all crash zones strongly rely on driving physics. That means time and speed are involved - and they can be used to improve the functionality and effectiveness of the crumple zone.

Specifically, Newton’s Second Law of Motion defines force as mass times acceleration. As such, faster speeds have more force and less acceleration will result in less force. In fact, a crumple zone works to absorb the force, but at the same it also actively seeks to decelerate the vehicle to lessen the forces exerted on the vehicle as a whole.

Car tyre close-upA good car tyre, with a thick tread will help improve braking and deceleration.

Since deceleration is important in car accidents, quick and reactive braking times will also provide more safety. Today, many vehicles feature automatic braking systems for this purpose. Of course, there are situations where braking ahead of time simply isn’t possible. Yet, even here, high quality car tyres can still help improve the efficiency.

Specifically, a strong grip will help keep the car connected with the road surface. It goes without saying that this will also depend on the weather conditions at the time. In wet weather a layer between the tyres and road can be formed causing aquaplaning and impeding crumple zones’ usefulness. Likewise, in more severe weather, winter tyres ensure good grip, which certainly proves valuable in these circumstances.