Predicting the development of traffic fatalities in Latin-American and Carribean countries. Paper presented at the OECD conference on road safety in Latin-American and Carribean countries, Sao Paulo, Brazil, December 1995.

Long-term developments in traffic growth and fatality rate can be rather well described by non-linear functions of time. The basics are an S-shaped function for saturating traffic growth (measured by annual motor vehicle kilometres or motorised vehicle volumes) and an exponentially decreasing function for fatality rate. Each function may be simultaneously modulated by cyclic or auto-regressive functions for deviations from these basic functions. By definition the product of traffic growth and corresponding fatality rate determines the road fatalities. Therefore, reducing road fatalities only can be observed if the fatality rate proportionally decreases more than the traffic grows. The general validity of the mathematical analysis for traffic growth and fatality risk development are first illustrated by the remarkable fit for the data analyses of long time-series on kilometrage, fatality rate and fatalities in the USA. The analyses for the USA and many other highly motorised countries have shown that the slope of the exponential decreasing fatality rate generally is dependent on the slope of the S-shaped trend in traffic growth. This relation between the underlying main trends of growth and risk as well as the dependence between their deviation patterns from the main trends are theoretically understood as evolutionary growth and delayed risk adaptation of technological systems under deterring and accelerating socioeconomic influences. This interpretation as a socioeconomic technological evolution of road transport and its evolutionary risk adaptation implies inherently interdependent developments as in biological evolutions where growth also implies adaptation. Also for Latin-American and Caribbean countries the growth of motorised traffic is made possible by socioeconomic changes, while the cyclic modulations of S-shaped traffic growth may express economic upsurges and depressions with delayed effects on risk adaptation. Quantitative data analyses are only shown for Brazil and Chile, because for other Latin-American and Caribbean countries no consistent long time-series of fatalities are available. If traffic growth is not accompanied by a more than compensating risk reduction the result is disastrous for road safety, as is shown by the analyses and prognoses of Brazil and Chile as well as by the estimation for the total 35 Latin-American and Caribbean countries. In order to prevent a worsening safety outcome of traffic growth, such as the tentatively predicted annual 120 thousand road fatalities in the total of the 35 Latin-American and Caribbean countries around the year 2015, the investments in road safety must be given an as high priority as the investments for traffic growth. If the also briefly summarised road safety policies are not established, the total of road fatalities will amount to nearly two million between 1995 and 2015 in the 35 Latin-American and Caribbean countries. By the most effective road safety policies a total of one million lives and the waste of about 400 billion US-dollar macro-economic costs could be saved. It justifies road safety investments of 20 billion US-dollar per year in the total of the Latin-American and Caribbean countries over the next 20 years