Road safety in bits and pieces : for a better understanding of the development of the number of road fatalities. Proefschrift Technische Universiteit Delft TUD.

This thesis describes a method in order to get a better understanding of the development of traffic safety. The unsafety of traffic, expressed as the annual number of road fatalities, has shown a remarkable development in the Netherlands over the past years. In about 1950 there were approximately a thousand fatalities annually. Between 1950 and about 1972 this number increased approximately exponentially to almost 3500. Afterward, a decrease followed to about 650 fatalities in 2012. This means that the annual number of fatalities decreased during most of the years, but not always and not at the same pace. In some years there was even an increase (as in 1976 and 1977, when there was an increase of more than 100 fatalities). And also in 2011 and 2012 the number of fatalities increased in comparison to the previous year. In many other high income countries a similar development was seen: an increasing number of fatalities until 1972 and a decrease thereafter, with irregular jumps up and down in the annual number of fatalities. The goal of this thesis is to research how these developments can be related to factors such as the amount of traffic, road safety measures implemented by the government, etcetera. The thesis is a search for the way to define how these factors determine road safety. The emphasis is on fatalities, because the data for those are the most reliable ones, both in the Netherlands as in many other countries. Here we focus on the analysis of Dutch data. However, the final goal is to develop a general method which can also be used to analyse road crash data for other countries