Factors contributing to road fatalities: Analysis of in-depth investigation data from passenger car intersection crashes and from collisions between bicycles and motorized vehicles

In-depth studies were made of intersection crashes involving a passenger car, and of collisions between bicycle and motorized vehicle. Most intersection crashes were collisions between left-turning car and oncoming motorcycle or heavy vehicle. The most frequent contributing factor for the turning driver was failure to observe the oncoming vehicle, because of attention being focused on other aspects of traffic. In most bicycle crashes the driver reported failure to observe the bicyclist. This was found to be a result of inattention and/or poor visibility. Low expectation of seeing bicyclists in traffic was a likely contributing factor to inattention. Poor visibility was partly due to the road design or environment, and partly to the vehicle. Especially for heavy vehicles the blind zones make it difficult to observe bicyclists close to the vehicle. The analyses give rise to recommendations for improvement regarding data collection in in-depth analyses of road crashes.