Opportunities and limitations for intersection collision intervention-A study of real world 'left turn across path' accidents.

Turning across the path of oncoming vehicle accidents are frequent and dangerous. To date not many car manufacturers have introduced Automated Emergency Braking (AEB) systems addressing this type of conflict situation, but it is foreseeable that these scenarios will be part of the Euro NCAP 2020 rating. Nine out of ten collisions are caused by the driver of the turning vehicle. An AEB system evaluating the ego and conflict vehicle driver's possibilities to avoid a pending crash by either braking or steering was specified for application in various constellations of vehicle collisions. In virtual simulation, AEB system parameters were varied, covering parameters that are relevant for driver comfort such as longitudinal and lateral acceleration (to define avoidance possibilities), expected steering maneuvers to avoid conflict, and intervention response characteristics (brake delay and ramp up) to assess the safety benefit. The reference simulation showed a potential of the AEB system in the turning vehicle to avoid approximately half of the collisions. An AEB system of the straight going vehicle was less effective. The effectiveness of the turning vehicle's AEB system increases if spatial limitations for the collision-avoidance steering maneuver are known. Such information could be provided by sensors detecting free space in or around the road environment or geographical information shared via vehicle to cloud communication. AEB interventions rarely result in collision avoidance for turning vehicles with speeds above 40km/h or for straight going vehicles with speeds above 60km/h. State of the art field-of-views of forward looking sensing systems designed for AEB rear-end interventions are capable of addressing turning across path situations.