2.3.1 - Secondary Vehicle Safety: Steady Progress

Version 3


    Innovation in every area


    Ever since the obligation to wear seat belts came into widespread application - the first sweeping measure to curb bodily injuries from accidents - secondary vehicle safety has developed rapidly and in a variety of directions. Today it encompasses a large number of systems.

    The following are some of the main measures adopted:

    • Seat belts: with 2, 3 or 4.5 anchorage points (for children), fitted with a pretensioner and load limiter, safety harness, etc.
    • Child restraint systems (CRS): carrycot and safety net, rear-facing child seat, seat with harness restraint, booster seat, etc.
    • Airbags: frontal, side, curtain, seat cushion, airbags for the driver and the passengers (front and rear), belt bags, pedestrian airbags, etc.
    • Head rests and specific anti-whiplash systems
    • Crumple zones (bodywork, chassis, hood, bumpers, etc.) These zones fold and buckle on impact, absorbing a maximum of kinetic energy, protecting the passenger compartment (designed in far more rigid materials) and limiting deceleration for the occupants. Deceleration force is what causes serious internal injuries.
    • Side impact protection beams, to increase the resistance of the passenger cell and dissipate impact energy
    • Passenger compartment made of a reinforced, crush-resistant structure that protects passengers' survival space
    • Engine mount designed in such a way as to prevent the engine block being rammed into the passenger compartment during a frontal collision
    • Rack-and-pinion steering or collapsible or telescopic steering column, to prevent the column entering the passenger compartment in the event of a collision
    • Laminated windshield, which, because it does not splinter into jagged pieces in an accident, reduces the risk of injury (and especially eye injuries)
    • Impact-resistant fuel tanks, which minimize the risk of explosion or leakage in the event of an accident
    • Fire-resistant materials, and fabrics and plastics that do not give off toxic vapors in the event of fire
    • Substantial progress achieved through accident research

    The continuous improvement in passive safety has been made possible by the development of accident research, a discipline that draws on science and statistics to analyze, among other things, the injuries caused by different types of accident, along with their severity and their repercussions on road mortality.

    As we find out more about the injuries caused by vehicle deceleration and the many mechanical and physical phenomena involved in accidents, depending mainly on vehicle speed at the time of the accident (energy transfer to within the human body, impact of the brain on the skull, submarining, cervical whiplash, etc.), we can improve seat belt design, for example by increasing the number of anchorage points, or adding the pretensioner and the load limiter.

    The latest advances in accident research have led to the invention of seat belt airbags for the rear seats of vehicles, which help dissipate deceleration forces and reduce their impact on passengers.

    The work of accident research laboratories is therefore vital for advances in passive safety. In France, for example, automakers Renault and PSA joined forces to create the LAB (Laboratory of Accident Research, Biomechanics and the Study of Human Behavior) in Nanterre. Today the laboratory has a database of around 15,000 accidents involving 27,000 people and describing over 70,000 injuries.


    The pressure of crash tests

    The significant advances in secondary automobile safety are also the fruit of the widespread use of crash tests and the dissemination of their results. By simulating different accident types and configurations, crash tests help us understand their effects on the human body, and devise more effective technological and industrial solutions. But crash tests have another important outcome: by comparing and rating the performances of the various automakers, they have a significant influence on what motoring consumers buy, and are a major differentiator for the manufacturers involved.

    In the countries with the most advanced active safety, the organizations that run crash tests play a major role in the process of continuously improving passive automobile safety.

    In Europe, for example, the majority of crash tests are performed by the six laboratories in the Euro NCAP association, which assesses vehicle safety against four main criteria: adult protection, child protection, pedestrian protection and safety assist.

    Regularly publishing and disseminating the tests performed by this body shines a spotlight on primary and secondary automobile safety, encourages manufacturers to invest heavily in this sector and removes any temptation to cut corners with safety. In 2008, for example, Euro NCAP brought out a series of crash tests that showed that 80% of car seats did not protect occupants from whiplash. The result was swift improvements in the design and manufacture of the seats in question.

    Similarly, Euro NCAP's decision in 2009 to include pedestrian safety in the overall score it awards prompted a string of innovations, including the external airbag.