Presentation from Mr Davidsson on behalf of EEVC (GTR7-06-09).

Progress update on a study to investigate the correlation between rear impact seat test results and Folksam insurance data for a range of vehicle models. Insurance data from 1995 to 2008 were used. Two risk measures were assessed:

• - symptoms > 1 month, and
• - risk of permanent medical impairment (it takes up to three years to establish this, so no data more recent than 2008 in the study).

Seat test data were from existing databases using BioRID II e and g, with two different H-point tools.

Results were reported for groups of seats from different vehicles in which the seat design was about the same. NIC, upper neck shear force (Fx, head rearward), and head-to-T1 angle gave the best correlation with risk of permanent injury in these preliminary results. It was noted that some seats show an opposite trend for some individual criteria, even for seats with markedly reduced risk. This was taken to show the need for multiple criteria.

It was noted that the analysis will be repeated later this year, when it is expected that there will be three times as many data available. Occupant gender will be controlled in the updated study( there should be enough data to do this). This study looks at the ability of a test with BioRID to discriminate between seats with different risk in the field [where drivers are of different size, gender, seating position, posture etc.]. Action Mr Davidsson to complete the study by the end of 2011, and to compare the results with the recommendations on criteria coming from biomechanical studies. Also to contact Dr Ono and discuss collaboration.

It was noted that R2 would not be expected to equal 1, as noted in the slide, but a low R2 still indicates that the parameter is a poor predictor of permanent injury. Also it is not clear that using several parameters with poor R2 will give a better overall prediction. Mr Frost noted that these issues will have to be discussed in future meetings.

It was noted that Nkm was recommended, in preference to the individual forces and moments because the individual forces and moments gave very low correlations. It was hypothesised that the variations in these individual parameters is masked when they are combined in the Nkm calculation.