Documents (Latest posted on 4 Mar 2021)
Related Meetings : Whiplash Criteria Workshop | Session 2
Documentation Discussion/Report

The draft agenda was approved with additions (see WCWID-2-01):
- Presentation from Johan Davidsson (JD) on a new approach how to derive injury criteria from insurance data (WCWID-2-05)
- Presentation from BL on seat performance/injury criteria for regulatory purposes (WCWID-1-04)

5.b. Proposal from Japan
Dr. Koshiro Ono gave two presentations (WCWID-2-02, WCWID-2-03) explaining the background research and the justification for the limits proposed by Japan.

Injury CriteriaWAD2+
82.9% value
NIC Max23
Upper NeckFX (backward)640
MY (Flx/Ext)34
Lower NeckFX (backward)640
MY (Flx/Ext)34
Units: Force (N); Moment (Nm).

IV-NIC=1.1 is correlated with AIS1+=50% and WAD2+=82.9%. This is how the proposed limits for NIC, upper and lower neck forces and moments were derived.

BL raised a concern with regard to the 82.9% risk of WAD2+ neck injuries. If the group shall bring the proposal to GRSP, one of the contracting parties may ask why we accept a risk of approx 83% for an injury. For someone who is not familiar with the group’s discussion this risk might sound very high. This could lead to the question how the proposed criteria would correlate with a 50% WAD2+ risk or even lower. He said that the group needs to be prepared for such type of discussion within GRSP or even WP.29.

It might be better to relate the proposed limits for the criteria to something where the risk “sounds” lower (e.g. PMI or something else). This could avoid discussion.

However, Japan showed data (from Anders Kulgren) which showed that there is a reduction of claims about 63% for “Whiplash Seats” (mainly Volvo WHIPS). He also showed that from JNCAP data that there is no good correlation between backset and score (rating). This is not surprising as this is highly depending on seat design. However, it might be of importance for discussions about having a dynamic test as an option if the geometric requirements are passed (as it is in the current GTR).

It was also shown that HIII is not an acceptable tool for whiplash testing (e.g. inverse flexion).

KO was also presenting JNCAP data from the 17.6 kph and 20 kph pulse. The results have improved over time even when the seats are exposed to higher energy. This is also an experience from Euro NCAP.

5.c. New Approach by Chalmers
Dr. Johan Davidsson showed a new approach (WCWID-2-05) on how to develop injury criteria risk functions based on the data he presented in former meetings. The risk functions will be generated in following way:

a) Generate risk functions for the 17 groups included in the Davidsson and Kullgren IRCOBI 2013 paper will be generated. Data will be turned into binomial data by groping the data into better or worse than a state of the art.
b) Each accident that is included in the Folksam data base and for which there is accident reconstruction data available will be included in a large volume regression analysis. The main disadvantage is that the crash severity is unknown (a generic pulse and seating position is used in the reconstructions) and risk curves will be to some degree influenced by the generic pulse used in the accident reconstructions.

This approach can be used not only for NIC but also for Forces and Moments.

JD is aiming to provide this data for the London meeting.

5.d. On Candidate Seat Performance / Injury Criteria for Regulatory Purposes
BL showed a summary of experience from Euro NCAP tests from the last years (WCWID-2-04). Most of the European (standard) seats have no problems with the proposed criteria. Out of 152 models tested between 2011 and 2014, only 4 vehicles had a whiplash pulse score capped (mainly due to rebound velocity). No capping was applied for one of the candidate injury criteria NIC and Upper Neck Fx. The other candidate criteria like My are measured but not assessed.

However, it should be noted that only the seats of the best selling version are tested at Euro NCAP. In general, no special sports seats or high sophisticated luxury seats are tested within the Euro NCAP programme.

Euro NCAP whiplash tests are currently performed in 7 European labs which received “Euro NCAP accreditation”. Different BioRIDs are used which are certified according to the “old” procedure.

Based on the data and by a comparison of the different proposals BL recommends the following limits for further discussion within the GTR 7 group:

  • NIC 23
  • Upper and Lower Neck Fx 360 N
  • Upper and Lower Neck My 30 Nm.

BL said that a status was reached where the group could also define something as “good practice” or based on the experience of JNCAP and Euro NCAP (may be IIWPG) set limits for some criteria to set a minimum standard and to sort out very cheap and bad seats (which could have a good geometry).