In September 1999 the Dutch Accident Research Team (DART) within TNO Automotive started with the in-depth investigation of traffic accidents. In this paper, the methodology, working procedures and experiences of the team are described and explained in detail. Furthermore, an elaborate description of a European study of Powered Two- Wheeler (PTW) accidents is given: MAIDS (Motorcycle Accident In-Depth Study). Some preliminary analysis results of the Dutch part are shown. Results on accident configurations, accident causes, injuries, collision speeds and helmet damages are presented. The results were also compared with former foreign studies. The preliminary results give interesting insight in some aspects of PTW accidents. Therefore, it can be expected that highly valuable insights can be gained from the project when finalised.