Report numberRA-2006-104
TitleRelation between vehicle type and accident severity.
SubtitleInternational literature study on accident severity in relation to the type of vehicles involved.
AuthorsTobias Denys
Published byPolicy Research Centre for Traffic Safety 2002-2006
Number of pages49
Document languageDutch
Partner(s)Vlaamse Instelling voor Technologisch Onderzoek
Work packageOther: Vehicle technology

The number of large and robust passenger cars (SUV’s, minivans, …) on the road is increasing, not only in the United States but also in Europe. Following this increase, international research into the outcome of accidents involving these vehicles has started. The evolution in weight of vehicles as well as crash compatibility plays an important role in this sort of research. This report provides an overview of the international state of the art regarding this subject. 


From this international literature study it appears that large and robust passenger cars like Sport Utility Vehicles (SUV’s) and to a lesser extent minivans, pose a problem to road safety. This is proven by European as well as North-American studies, and is confirmed by research from automobile manufacturers. When a normal passenger car is involved in an accident with an SUV or minivan, its occupants are more likely to suffer serious or lethal injury compared to an accident between two normal passenger cars. This is the case for both frontal and side collisions. The most dangerous accident type appears to be a collision where an SUV or minivan strikes a normal passenger car in the side.


Almost all cited studies found a relation between the difference in weight of two cars involved in an accident and the injury severity of the occupants of the lightest car. Since SUV’s and minivans are heavy cars, it is clear that when they collide with a lighter passenger car, they pose a greater threat to its occupants. In a few studies, this higher aggressiveness of SUV’s and minivans disappears when the data is corrected for weight. However, a number of studies prove the opposite. According to these studies, the higher aggressiveness of SUV’s and minivans is not only due to their higher weight.


The two main characteristics of SUV’s and minivans that were said to have a substantial influence on their higher aggressiveness are design differences and a higher frontal stiffness. The height of the frame rails in the bumpers of these large and robust passenger cars does not match the height of the frame rails in the bumpers and the sill in the door of normal passenger cars. To ensure the safety of car occupants, the frontal stiffness is designed dependant on its mass (the heavier the stiffer). This difference in frontal stiffness causes the occupants of lighter cars to be less protected when colliding with a heavier car.


In this report a recommendation is formulated regarding a revision of the crash tests that are performed in the European programmes. A modification or extension of the crash test programme is required due to the changes in the vehicle fleet and the consequences of crash incompatibility. A second recommendation concerns an improved design of the structural parts of cars. Mainly the frame rails in the bumpers of large and robust passenger cars should be designed to interact with those of smaller cars. A general introduction of so called side or curtain airbags is recommended as well. These restraint systems reduce the risk posed to occupants when their vehicle is struck in the side.


Additional research needs to be conducted into the Belgian situation regarding the relation between vehicle type and accident severity. Previous research pointed out that the required data to carry out such a study is present. American research proved that SUV’s do not only pose a greater threat to occupants of the collision partner, but also to their own occupants in single vehicle crashes. Investigating the Belgian and to a larger extent the European situation regarding single vehicle crashes involving SUV’s, is necessary.

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The Policy Research Centre for Traffic Safety carries out policy relevant scientific research under the authority of the Flemish Government. The Centre is the result of a

cooperation between Hasselt University, KU Leuven and VITO, the Flemish Institute for Technological Research.


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