Airbag seats, a revolution in continuous evolution
We look at the reasons why child restraint systems (CRS) do not have airbags
Since the 1990s, airbags (one of the most important passive safety elements in a car) have revolutionized occupant safety. The decline in the number of road accident fatalities is due, in part, to the massive use of this device in vehicles.
The purpose of airbags is to cushion the impact of the occupants against various rigid elements inside the car, such as the steering wheel, dashboard or windshield. This protection is also really effective if the occupant is also wearing their seat belt. Since 2006, two front airbags have been mandatory in all vehicles.
As is well known, the concept behind the airbag is based on reducing the speed of the head and chest by means of a cushion that inflates rapidly in front of the occupant and gradually deflates as the head and chest come into contact with it. Part of the secret of the invention lies in the deflation of the system. The image that appears in countless movies, where the airbag remains inflated, is totally false. If that were to happen, the occupant would bounce off the airbag, with uncontrollable consequences.
The fact of being able to control the braking speed of the head and chest led engineers to work with the seat belt, making its restraint less aggressive and allowing them to limit, in a controlled way, the loads received by the chest and pelvis. Today, as a result, the seat belt and airbag are a complete and complementary system that protects life in the event of a collision or sudden stop.
Following the development of the front airbag, the side airbag was introduced. It uses the same principle but protects the head in the event of a side collision.
None of this would have been possible without a reliable method of detecting the impact, in sufficient time for the airbag to deploy fully before it comes into contact with the occupant.
And this has certainly been the first major obstacle when applying an airbag system to a child seat: the signal that triggers the airbags when a collision is detected is part of an internal system within the car. The child seat is external to this and therefore would have to detect the collision itself.
This makes it very complex to set the right moment for the airbag to deploy, taking into account an infinite number of collision scenarios. This is not possible with a child seat.
The second issue is that it is physically challenging to deploy an airbag in front of the child, as a protective shield, since there is no supporting surface such as a steering wheel.
It should be remembered that for an airbag to function effectively, it must not be in the occupant’s space, instead it is the occupant who moves into the space of the deployed airbag. The consequences of the former situation, as we mentioned earlier, involve unknown variables, as there is no precedent for an airbag designed to occupy a space that already has a person in it. It would be like moving the driver’s seat closer to the steering wheel and then activating the airbag.
Thirdly, a child is a constantly growing being and making an airbag that will adapt to the entire range of their height and weight is complicated.
Fourthly, an airbag is an active element, providing a force in a specific direction. It is therefore, capable of inflicting injuries. The tests required to check their function must include many factors, far beyond those required in a type approval, as is the case when adjusting airbags in cars. However, the costs involved in carrying out all this testing would be prohibitive for most child seat manufacturers. The airbag must not contribute any additional forces to the child. This means, for example, that if the system did not deflate properly it would increase occupant bounce, making it unacceptable in terms of CRS occupant safety.
Last but not least, the benefits of this would have to be be very evident. As we have always said, children should travel in a rear-facing position until they are at least 4 years old, because this has been proven to provide them with the highest degree of safety. Using an airbag only makes sense in forward-facing seats and, therefore, the safety of an airbag system must be equal or superior to that of a rear-facing seat in order to be considered a valid option.
All these challenges, no doubt being considered by potential airbag seat manufacturers, will undoubtedly lead to further improvements in the safety offered to young children.