Transportation of people and goods has increased gradually over the years with the consequence of injuries and fatalities to people in the transport system. To describe the injury problem in the transport system, and to understand the mechanisms why accidents and injuries occur, require an extensive collection and analysis of field data. Field data has over the past fifty years served as a very important base for the development of safe vehicles and has strongly contributed to correct priorities, an improved understanding of the complex mechanisms, and provided the opportunity to evaluate the impact of measures taken. This article aims at providing a short overview of how field data is used as the basis for the development of safe vehicles. A few examples are highlighted to illustrate the development, although without claiming to provide a comprehensive picture.