1. Hur leder kritiska händelser till allvarliga olyckor? Johan Engström, Volvo Technology Transportforum, Linköping 2011-01-13

2. Accidents and incidents p

9. A general accident model Normal driving Critical event Crash Schema Situation Conflict ? Successful bottom-up selection? No Near crash time Reactive barrier Proactive barrier Yes No Yes

10. Real world example 1: Car-bicycle crashes at intersections and roundabouts (Summala and Räsänen, 2000)

11. Interpretation – Summala study Driver’s schema: Look for cars to the left Bottom-up selection: None since the bicyclist appears outside the field of view Actual situation Bicyclist approaching from the right Normal driving Critical event Crash Conflict ? No Reactive barrier Proactive barrier Yes

12. Real-world example 2: Rear-end crash in the 100-car study Narrative (by VTTI analyst): Subject driver is approaching a right turn at an intersection. The lead vehicle briefly stops at stop sign, then moves forward as if completing the turn. As the subject driver looks out his left window to check traffic, the lead vehicle stops again. The subject vehicle hits the lead vehicle in the rear. Inopportune glance. Event 8633 Brake Gaze Speed Impact Acceleration

13. Interpretation – 100 car rear end crash (event 8633) Driver’s schema: Lead vehicle will continue to turn -> OK to look left to check traffic Actual situation Lead vehicle stops again Bottom-up selection: None since the lead vehicle braking occurs outside the field of view Normal driving Critical event Crash Conflict ? No Reactive barrier Proactive barrier Yes

14. Aggregate analysis, 8 rear-and crashes Homogenous mechanisms!

15. Aggregate analysis, 8 near crashes More heterogenous mechanisms!

16. Lee et al. (2007) quantitative analysis of 100-car study rear end events (same data) Eyes-off-road is what distinguishes the crashes TTC similar between crashes and near crashes