Fatal car to moose collisions : Real-world in-depth data, crash tests and potential of different countermeasures

• Vehicle collisions with large animals constitute a high risk of serious or fatal injuries, for example in northern America, Europe and Japan. In Sweden approximately 5,000 car collisions with moose occur annually. The change of velocity and acceleration is in general very low, but the car structure is not designed for collision with large animals at high speed. The objectives were to evaluate occupant response and vehicle structure in crash tests; to investigate the factors involved in real-world fatal crashes in Sweden; and to evaluate the potential of Autonomous Emergency Braking (AEB) to increase moose car collision avoidance and survivability. Five crash tests were conducted with cars with different size and characteristics, such as glass and sun roof. A moose crash dummy was impacted at 70 km/h. The Swedish Transport Administration (STA) national database of fatal collisions was used to study fatalities (n=47) in collisions with moose during the period 2005-2016. The analysis focused on collisions where the primary cause of fatality was the collision with a moose. The crash tests showed that a moose collision could be survivable at 70 km/h with an acceptable distance to the header structure. None of the tested cars had an intrusion by the moose into the occupant compartment. The results of the in-depth data analysis showed that a critical factor for a fatal injury was whether the roof was partly or completely ripped off. Downward deformation of the front header structure was also critical together with Apillar deformation. In 24% of the accidents the moose was partly or completely trapped inside the occupant compartment. In 90% of the fatal collisions it was darkness or twilight. In more than 85% of the collisions, no evidence of braking could be detected prior to collision. All of the collisions occurred on rural roads and 83% of the fatalities occurred on roads with speed limits of 90 km/h or above. In eight accident scenes there were moose fences to prevent the moose to access the road. In those accidents, however, the fence was either damaged or had open sections. The analysis of road-side area showed that in many of the moose accidents the side view was enough to allow detection of the moose by an AEB sensor. A critical issue is the ability of the sensors to detect the moose in darkness. The study of the potential for AEB with moose detection was conducted under the assumption that night vision sensors are available, such as infrared sensors or light amplifying technique. With a threshold of 70 km/h for car-moose collision survivability, the results of the analysis showed that AEB had a potential to save (~40%) 18 out of 47 lives. It is suggested that road fencing is preferable on roads with speed limits above 90 km/h, and below 100 km/h, moose AEB has a potential to avoid fatal moose crashes.

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