Error analysis and in-depth accident studies

After the first two years of data collection, four research specialists involved in the In-Depth Accident Study (IDAS) which was carried out in Salon-de-Provence (France), analysed 72 accidents (115 road users). The aim was to improve methodology, and to gather aggregated data which could be used to start exploratory research on specific topics. One of these was called 'task and error analysis', because an attempt was made to find out which mechanisms led to failures in the function event sequence, and link these failures with the activities being carried out by the road user at that time. Different aspects were considered, mainly task competition, attention distribution, and time pressure. The results were expressed in a typology of accident mechanisms, with a description of 15 main categories which fitted the data adequately. It is hoped that the similarities in accident causation which are shown up in each category will lead to similarities in preventive or remedial measures.