Pre-crash motion and conditions of bicyclist-to-car crashes in Sweden

The aim of this study was to study the pre-accident crash conditions of car-to-bicyclist crashes. Two datasets were used. The Swedish Transport Administration fatal database was queried 2005-2014 for fatal car-to-bicyclist crashes. The STRADA database was queried 2010-2014 for AIS2+ car-to-bicyclist crashes. The focus of the study was on the bicyclist and car motion preceding the accident, but parameters included were also traffic environment, light and weather conditions, victim age etc. To understand the pre-crash kinematics, each crash was studied in detail. The query resulted in 104 fatal and 435 AIS2+ car-to-bicyclist crashes. It was found that the two most common injurious car-to-bicyclist accident scenarios in Sweden was the bicyclist crossing a road (from left or right) where the car was driving straight. This was most common in urban areas. For fatal accidents it was followed by a scenario where the car was passing a bicyclist on a straight rural road and the bicyclist turned in front of the car. For injured bicyclists it was followed by a scenario where the car was turning left and the bicyclist was crossing the road that the car was turning into from right side, a typical urban junction scenario. In all four scenarios daylight and dry conditions were dominating. These four scenarios represented around 70% of all accident scenarios for both AIS2+ and fatally injured bicyclists in Sweden. When developing active safety systems for passenger cars, it is important that they are based on the most common accident types in real traffic regarding car and bike motion, lighting and weather conditions and size of the bicyclist. The information in this study, in conjunction with studies from other databases, could be used to develop test scenarios to evaluate and develop these systems.