The main injury mechanism in nearside impacts is normally linked to the relative impact velocity of a bullet vehicle or an object. The change of velocity of the target vehicle has been considered to have a minor role, at least for a nearside occupant. It has, however, been complicated to distinguish between impact velocity and change of velocity in real life accident analysis.
In the present study, the aim was to analyse real life side impacts to isolate the roles of impact velocity and change of velocity in relation to injury risk. The analysis method used was matched pairs used in a modified way, where different combinations of vehicles of varying mass ratios were studied according to relative injury risks to the driver. The data set used for the analysis was crashes in Victoria, Australia.
The results show, that while impact velocity is of major importance for the risk of injury, change of velocity also plays a major role in nearside impacts. In far side impacts, impact velocity is of minor importance compared to change of velocity. In reality, it must be stressed that they are highly correlated.
The result of the study, if validated further, has implications for crash test configurations and validation of side impact safety design. One outcome might be that cars of different masses should be tested at different speeds, or that movable barriers should be varied in mass and speed depending on the mass of the target vehicle.