Head-on collisions between passenger cars and heavy goods vehicles: Injury risk functions and benefits of autonomous emergency braking

This study focuses on frontal crashes between passenger cars and heavy goods vehicles (HGV) in Sweden. The objectives are to estimate how risk for moderate and severe injuries (MAIS2+) for passenger car occupants correlates with change of velocity (delta v) in this type of crashes and to estimate the potential benefits of Autonomous Emergency Braking (AEB) on HGV and passenger cars in reducing injury risk. First risk curves were derived from Crash Pulse Recorder data from 85 real-world frontal collisions between passenger cars and HGV including 133 front seat occupants with AIS-coded injuries. Secondly, a case-by-case analysis was performed using 70 in-depth studies of fatal crashes collected by the Swedish Transport Administration. The possible additional braking time and impact speed reduction with AEB was calculated. Finally, the calculated speed reduction with AEB was applied on the derived risk functions in order to estimate the injury reduction. Results showed that with a given delta v the injury risk for car occupants was higher in frontal collisions with HGV than in similar collisions with another passenger car. AEB activated on HGV and passenger cars in frontal collisions could possibly reduce the closing velocity by approximately 30 km/h on average, which would result in a 73% reduction of MAIS2+ injuries on the passenger car occupants.