VEHICLE PROPERTIES DETERMINING AGGRESSIVITY
The objective of this study was to attempt to emp irically quantify the effect various measurable physical vehicle properties have on aggressivity. Expert opinion and literature review was used to select for measurement the vehicle characteristics most likely to affect aggressivity. They included, amongst others, such characteristics as vehicle mass and frontal stiffness, dimensional properties such as bonnet height and length and the placement of key mechanical components relative to the external surfaces of the vehicle. Data on physical vehicle properties by field measurement were collected for 73 distinct makes and models of vehicles for which a vehicle aggressivity index had been estimated.
As a preliminary analysis, multiple regression analysis was applied to identify those measured physically vehicle properties that were associated with the estimated vehicle aggressivity index. Marketing grouping of vehicles (small, medium, large, luxury and 4WDs) allowed the comparative analysis with 4WDs included and excluded from the sample data.
The results showed a high association between vehicle wheelbase, bonnet leading edge height and bonnet length and the vehicle aggressivity index for the whole fleet. Repeating the analysis with 4WDs excluded from the sample data revealed vehicle wheelbase was the only factor showing the high level of association with the vehicle aggressivity index.