The paper shows that long-term developments in mobility and safety can be related by an evolutionary growth and risk adaptation model. This model can be applied to historical data from Japan, USA, United Kingdom, and Germany, over long periods of time. Growth of mobility can be described by sigmoid curves which describe the road traffic saturation level and risk. The fatality rate follows a decreasing adaptation curve. A single peaked curve for the road fatalities per year, is a necessary result from saturating growth and steadily decreasing risk adaptation. Long-term predictions are given, based on time-related evolutionary trends and cycles. It is argued that the present stagnation in safety improvements in some countries are temporary cyclical effects of the recent larger increase in motorized mobility and stagnated decrease of the fatality rate. The relation between mobility growth and risk adaptation is seen as a result of the technological evolution of traffic in a self-organizing socio-economic system. The given model predictions may only hold for democratic countries and only as long as the predictions are not by-passed by a yet unknown evolution of a safer and more efficient transport system.
Abstract