Twenty years ago a text on traffic safety and the need for improvement typically started with a sentence claiming that the economical impact of crashes，injuries and fatalities was large and problematic.It was sometimes followed by a sentence that injuries and fatalities also caused suffering for the individuals and families.This is of course no sign of that those who wrote the texts were cold-hearted，but rather a mainstream expression of that the society was suffering from the individual's behavior in economical terms.This was also the background for the rational thinking that while mobility is the main functionality of the road transport system and the relative lack of safety was a given factor.Safety improvements that might reduce mobility or otherwise put an economic burden on the society had to be balanced with the economical benefits of the safety improvement.A safety investment was only defendable if the benefit to cost ratio was over 1，that is，the society's benefits were larger than the collective burden.Safety could thus be seen as a function of mobility.There have been several motives to improve traffic safety over the one hundred year history of mass motorization.In the very beginning，traffic safety was seen as a legal issue，but more and more the economical motives became the main driver for improved safety.What we see now is a very sharp change in the policies across the globe to see the lack of traffic safety as something that turn the individual citizen to a victim of a man made system that we can change of we wish and if we use scientifically sound methods.It is no longer the economical motives that are the main reason for improvement，even if they play a role.This leads to an approach where mobility is a function of safety and where safety is a framework to mobility that cannot be neglected or compromised.In the very beginning，the individuals were protected from cars through the red flag act where a person with a red flag walked in front of a car.The next step was to protect the society through a legal framework making each driver ultimately responsible for all consequences.Now we are rather talking about how we protect the individual from fellow road users and potentially even the society.The modern history of a scientifically based traffic safety work starts with William Haddon Jr，an epidemiologist that formed many of the frameworks we still use.His view on the individual suffering was in no way different to the current view，and his ground braking formulations of injury prevention and strategies for improvement are still perfectly valid.His background from the medical field might be the reason for the overall lack of moral condemnation of the victims of road crash trauma.In his work “On the Escape of Tigers：An Ecologic Note ”he described ten different strategies for road traffic injury prevention that we are using today，although in a much more sophisticated way.He also defined the expressions “passive” and “active” safety solutions in a way that we today have twisted nowadays that he probably would have argued strongly against.His definition was in fact very useful，as “passive” means a solution that is always working irrespective of the road user behavior，while “active” is a countermeasure that needs an action from the road user.A manual seat belt or a child restraint is therefore active safety countermeasures，while roundabouts or electronic stability controls on a vehicle are passive countermeasures.In any case，Haddon claimed with several examples that passive countermeasures are far more effective than active solutions.To rely on the individual's behavior to take the right critical decision in is in most cases not a stable and effective and he suggested that education or information alone were not only ineffective but could also potentially lead to inequities in the society.These are views that are still important when we make informed choices of safety strategies.We have a better understanding of that most safety improvements are combinations of attitudes and norms，regulations，technologies and system design.What we seem to understand better than in the days of Haddon is the role of management，how things get done in a complex society with many stakeholders，both public and private.This is one thing Vision Zero offers；a policy for management of safety，a guideline for the professional society in its relation to the individual society.Haddon also was firm in that kinetic energy needs to be in control to save lives.His first and foremost general strategies for prevention were elimination，limitation or mitigation of kinetic energy，followed by cushioning of energy.Later in his listing of ten strategies came strategies like warnings，education or enforcement.His view on barriers to hazardous energy is still valid and used extensively.This is also why mobility，as expressed by the amount of transport and time consumed is the balancing factor for safety.Both modern safety management as well as Haddon have reduction of kinetic energy trough speed as a key factor to improve safety if other strategies to improve safety are not accessible or effective. <<