Cars In The Future : Passive Safety
Return to Cars In The FutureIn the field of passive safety there are still large injury prevention gains to be made, and RoSPA believes that it should not be discounted as a tool to further reduce road casualties. The improvements in passive safety over the last 10 years has been shown to reduce casualty numbers and it would be error to assume that there is little more that can be done in this field, or that the evolution of passive safety has reached a plateau.
Despite advances in active safety, a good plan to prevent accident and injury prevention plan does not stop at the first level of countermeasures on the assumption that they will work. It is important that all occupants in the vehicle are offered a high degree of protection in addition to any prevention technology.
Much of the technology and theory for improving the safety of car occupants in a crash is understood, although the further development and refining of both will improve tests and protocols. Evaluation of databases like CCIS will identify new injury trends and highlight issues that crash safety will need to address in future.
There is also great potential for passive safety measures to be combined with active safety measures that gather information about the vehicle’s surroundings.
In terms of crashworthiness, vehicles are designed to perform well in series of specific front, side, and pedestrian crash tests. A good performance in these tests will result in a safer car in the real world, although every crash is different, and the passive safety systems on a vehicle would not be optimised for most of the circumstances in which a crash occurs.
Studies have shown that there is a relatively long period between a collision becoming unavoidable, and actually occurring. This time period could be used gather information to prime the vehicles restraint systems, and for an on board computer to decide how to best protect an occupant. In a way, the vehicle will ‘react’ to the collision.
Examples of this area of ‘pre impact’ protection may be a vehicle deciding which airbags to fire and how rapidly to fire them, or even adjusting it’s suspension and height to achieve a better geometric compatibility with a vehicle that it is striking.
The Future of Passive Safety
Passive safety is a relatively mature field although as in all sciences, today’s state of the art model is tomorrows sweeping assumption.
A better understanding of the mechanisms of how human injury occurs can be used to improve and crash testing program and passive safety systems, and also to further review and quantify their effectiveness. This understanding can also be used to refine and develop the injury criterion, which are used to set the experimentally measurable targets that dummies pass or fail in tests.
Improved dummy bio-fidelity will also help testing become more comparable to the real world.
A report was conducted by Loughborough University entitled ‘Review of Secondary Safety Priorities - Looking at where best to direct future resources’. This looked at not only the injuries that occurred most frequently, but also how costly they were. By focussing on these two areas, key areas for action that would bring the most benefit could be determined.
More work is also needed to protect older car occupants, who are more prone to injury in crashes. The reason behind this is that as people get older, the structure of the bone changes and the trabeculae that give it strength start to thin out, and the bone becomes less resistant to impact.
Not only is this a concern when an elderly occupant would be unfortunate enough to hit the inside of a car, but the magnitude and way that the forces from a restraint system (such as a seatbelt or airbag) are distributed over an occupant.
In future we may see vehicles designed and marketed for elderly drivers, with the restraint systems optimised for the elderly consumer.
Adaptive restraints will also have a role to play here, and occupant vulnerability and brittleness of the bones are variables that can be taken into account before deciding how to best to restrain an occupant. Early efforts have been made towards designing techniques that measure occupants bone strength.
Most legislative and crash test procedures test vehicles with a 50th percentile male dummy; in future legislative or consumer tests could deal with the 5th percentile female dummy and 95th percentile male dummy so that restraint systems are optimised for a range of occupants.
Computerised simulations and virtual testing may be a cost effective way of seeing how a restraint system would protect a range of occupants, although it would be almost impossible to use computerised simulations as a basis for legislation.
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