Citation

Koornstra MJ. IATSS Res. 1992; 16(2): 129-148.

Copyright

(Copyright © 1992, International Association of Traffic and Safety Sciences, Publisher Elsevier Publishing)

DOI

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PMID

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Abstract

It is shown that long-term developments in mobility and safety can be related by an evolutionary model of growth and risk adaptation. The model is applied to historical data of several countries over long periods of time. Growth of mobility can be described by sigmoid curves with a saturation level (taken from biology or economics) and risk in road traffic as the fatality rate follows a decreasing adaptation curve. A single peaked curve for road fatality's per year is necessary from the saturating growth and steadily decreasing risk adaptation. Such growth and risk adaptation curbs are related. Deviations from these of monotonic macro developments in mobility and risk are also time-dependent and related. Deviations from sigmoid mobility growth tend to be cyclic and seemed to be reflected in delayed and reduced cycles of deviations from the steadily decreasing fatality curves as a growth-dependent safety adaptation. Relatively less increases in mobility seem to be followed by a stagnated decrease or even an increase of fatality rate, as if the system becomes less well adapted. On the basis of these time related evolutionary cycles and trends, long-term predictions are given. It is argued that the momentary stagnation and safety improvements in some countries are temporary cyclical effects of the recent larger increase in motorized mobility and stagnated decrease of the fatality rate. In the long run the increase of mobility levels off to a saturation level for motorization. As a consequence of the model and its bit to data, the fatality rate seems to decrease to virtually zero as time proceeds to infinity, but the injury rates seems to stabilize on a nonzero level. The impact of these new findings and of the underlying theory of evolution and adaptation of discussed. The relationship between mobility growth and risk adaptation is seen as a result of the technological evolution of traffic in a self organizing socioeconomic system. The utility of voter mobility leads to an increase of vehicle co-authors, which in turn asks for more time-consuming plans, investments and realizations of road network enlargements and improvements. Safety benefits from such enlarged and improved infrastructures, as well as from the renewal of the national car fleet by safer cars, from revisions of traffic rules, from improved practices of enforcement, from driver education, and from the ever increasing collective driver experience. These sequences of replacements of subsystems enable the traffic system to grow and are also the cause of the lag in safety improvement. The mathematics of the theory leads to process descriptions and predictions which are only a function of time. The validity of the theory and its predictions may only hold for motorization in democratic countries, since that Democratic control seems to determine the socioeconomic self organization of the transport system and its lawful developments of growth and safety. Moreover, these predictions may only hold for our own traffic system, but could be bypassed by a yet unknown evolution of a new and safer transport technology.