Summary Workers who received compensation for a work-related traffic accident (WRTA) accounted for about 2% of all workers compensated by the Commission de la santé et de la sécurité du travail du Québec (CSST). However, traffic accidents accounted for 25% to 30% of all work-related accidental deaths. Traffic accidents are the leading cause of work-related accidental deaths. As a result, the IRSST sponsored a study of WRTAs in Québec. The study had two parts, and a separate report has been published for each part. The first part of the study was a review of the literature on WRTA risk factors (IRSST report R-791). The second part was an innovative statistical data analysis, the subject of this report. Through the combined effort of the CSST and the Société de l’assurance automobile du Québec (SAAQ), a unique database covering over 8000 workers compensated by the CSST following a traffic accident that took place between 2000 and 2008 was created.Most workers involved in a WRTA were driving a vehicle (83%), but some were passengers (11%) or pedestrians (6%). Close to one-quarter of WRTAs involved truck drivers or delivery drivers, 10% involved police officers or detectives, 6% labourers or material handlers, 5% bus drivers and just under 3% people in the nursing, therapy and related assisting occupations. Together, these occupations accounted for close to half of the workers involved in WRTAs. The sectors of activity where the most WRTAs occurred were public administration (22%), transportation and warehousing (20%), trade (14%), other commercial/personal services (12%) and health and welfare services (10%). Close to four of every five victims of WRTAs were from these sectors. Using multiple correspondence analysis and cluster analysis, seven clusters (types) of WRTAs were identified. The largest cluster (in terms of number of workers compensated) included mainly collisions between two or more vehicles where the speed limit was 60 km/h or less; one-quarter of all WRTAs were in this cluster. The second largest cluster (23%) also included victims of collisions between two or more vehicles, but the accidents occurred where the speed limit was higher. The percentage of serious or fatal accidents in this cluster was double the average, 31%. A third cluster (18%) included workers injured mainly in accidents involving only one vehicle—a single-vehicle off-road accident, for example, or a collision with a stationary object. The fourth cluster (16%) included mainly workers who had no apparent injuries at the time of the accident according to the police report. A fifth cluster (10%) covered mainly accidents involving emergency vehicles such as police cars, ambulances or fire trucks. The sixth cluster (6% comprised accidents involving pedestrians, one out of four of whom were seriously or fatally injured. A last cluster (2%) was formed basically of workers injured in a forest environment; though few in number, these accidents had the highest percentage of serious or fatal injuries (one in three accidents). Characteristics that differentiate these seven clusters include type of vehicle, speed limit, environment, nature and severity of injury, probable cause of the accident, type of accident, condition of the driving surface, time of the accident and worker’s sex. There were also significant differences between the clusters with respect to number of days of compensation and total benefits paid.The prevention of work-related traffic accidents is a challenge for the workplace and the CSST. The results of this study contribute to a better understanding of the problem and provide information that can help in developing prevention programs specifically adapted to each of the work-related traffic accident clusters identified.