Misuse of Booster Seats. A laboratory observation study on children’s performance during buckling up on an integrated booster cushion and an aftermarket booster cushion.
Rapport, 2007

Motor vehicle crashes are among the leading causes of morbidity and mortality among children in the age group of 4 to 8 years. It is of utmost importance that the child is using correct restraints when seated in the car, taking into consideration age, length and weight. Booster cushions are important and effective tools in the effort to protect young children from injuries in car crashes. Injuries to abdomen and spine are nearly completely eliminated in accidents with children seated correctly on booster cushions compared to only seat-belts. Though, despite all benefits, there still remains a high amount of non-use and misuse of booster cushions. Therefore it is a need for continuous improvement of the safety for rear seated children. Studies of integrated booster cushions in the rear seat have shown benefits compared to aftermarket booster cushions, both in increasing the use rate and minimising the problems of misuse of the belt during buckling up, as well as better protection of the children in car crashes. The purpose of this study was to create a deeper knowledge about how children in the age between 4-12 years perform when they are buckling up on booster cushions in the rear seat. Two concepts of booster cushions were included; an integrated booster cushion (IBC) and an aftermarket booster cushion (BC). In addition, buckling up with seat belt only was also studied for the older children. The aim of the study was to obtain information of potential misuse; i.e. type and frequency of misuse, belt slack, and time to buckle up. Furthermore, the aim was to identify if age of the children and wearing a winter jacket had an effect. In total, 130 children in the age of 4-12 years participated in the study. The distribution between boys and girls was equal, as well as between children wearing or not wearing a winter jacket. The children were from the region of Göteborg and surroundings, where traffic safety aspects often are highlighted, due to large car manufactures in the area. Only children with some experience from booster cushions/seats were used as test subjects. During the tests session, each child buckled up on an integrated booster cushion (IBC) and an aftermarket booster cushion. The older children (8-12 years) also buckled up with seat belt only. Interviews, observations and measurements of height, time to buckle up and amount of belt slack were made. Photographs were also taken to document belt fit. The results showed that 77% of the children failed to perform correct belt routing under when buckling up on BC. Nearly all cases were severe misuse. Although the majority of the children were familiar with an aftermarket booster cushion with guiding loops for the belt, this high misuse rate occurred. The misuse rate for IBC was only 4% (5 cases of 128 children). For seat belt only no misuse was shown. According to the traffic regulation, children shorter than 1350 mm should use additional protective equipment than the seat belt when travelling in cars, which is equal to 54% of the children included in the study. However, only 26 % stated that they used a booster cushion/seat, which is alarming from a safety point of view. To conclude; the integrated booster cushion concept has many advantages compared to an aftermarket cushion with guiding loops, both from a safety and comfort point of view. It is easy and quick to handle; has few possibilities to misuse, has an intuitive design, the buckling up sequence is equal to buckling up with the ordinary seat belt, and younger children can buckle up correctly. The majority of children 6 years and older buckle up themselves today, and travel in cars several days a week. They need a restraint system that is comfortable and intuitive in design, easy and quick to handle, to achieve a high usage rate and maximum protection during a crash. The integrated booster cushion concept fulfils most of these demands to a high extent.


belt slack

integrated booster cushion

buckling up



Anna-Lisa Osvalder

Chalmers, Produkt- och produktionsutveckling, Design

Katarina Bohman

Maria Eriksson

Chalmers, Produkt- och produktionsutveckling, Design


Produktionsteknik, arbetsvetenskap och ergonomi


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