CR 175: Benefits of a Hybrid Side Impact Regulation (1998)

There are two fundamentally different dynamic side impact regulations in existence currently, namely FMVSS 214 in the USA and ECE Reg 95 in Europe. An earlier benefit study (Fildes, Digges, Carr, Dyte and Vulcan (1995) showed that both these regulations would be cost-beneficial if applied in Australia. Subsequently, Australia mandated a new Australian Design Rule ADR72 that calls for all new passenger cars to comply with one of two existing dynamic side impact regulations by 1999.

There is general agreement around the world that it is undesirable to have two different regulations for side impact protection and that they need to be harmonised. A proposal for a hybrid side impact regulation was developed in Australia recently (Seyer & Fildes, 1996) and a series of crash tests were performed which demonstrated superior crash performance outcomes over the two existing regulations.

To demonstrate the likely cost effectiveness of the proposed hybrid side impact standard, a Harm benefit analysis was undertaken using the Harm Reduction method previously used in other side impact benefit analyses (see Fildes, Digges, Carr, Dyte & Vulcan, 1995; Fildes, Dyte, Carr, Digges & Seyer, 1996).

Hybrid Standard Proposal

The current FORS proposal was outlined in Seyer & Fildes (1996) and contains features of the two existing side impact standards in Europe and the United States of America, including the FMVSS 214 crabbed movable barrier, the ECE R95 deformable barrier face, impact geometry as in FMVSS 214, BioSID dummies in the front and rear outboard seating positions, and ECE R95 injury criteria to the degree to which BioSID is capable of measuring.

The ATSB Road Safety have been working towards developing a hybrid side impact standard proposal, based on a crash test program undertaken at a crash test facility in Melbourne, Australia.

Data Sources Available

An Australia-wide database was necessary to assess the likely injury reductions for these standards. A detailed database was constructed in 1991 of national injury patterns by body regions, restraint conditions and contact sources, along with a series of resultant Harm matrices using BTCE human capital cost estimates (Monash University Accident Research Centre 1992). This comprehensive trauma analysis, based on over 500 real-world crashes examined in the Crash Vehicle File by the Monash University Accident Research Centre, offered a baseline trauma pattern upon which estimates of Harm reductions could be made.

Injury Reductions

As in the previous side impact benefit analysis in Fildes et al (1996), there was again very little published data available that reported on injury reductions associated with a hybrid standard, apart from the test results reported earlier in this study and some figures published by Dalmotas, Newman and Gibson (1994). Thus, it was deemed necessary again to assemble a panel of international experts to establish the likely injury benefits that would accrue to Australia for the hybrid standard.

A one-day workshop was organised in May 1997 in Washington DC comprising representatives from the car industry, government researchers, representatives of consumer groups and the study team. The workshop provided an up-to-date account of recent side impact regulation developments as well as the likely injury benefits to Australia by adopting the hybrid standard.

It was clear from the discussion at the meeting that many of the assumptions made in the earlier side impact benefit study (Fildes et al 1995) had not been substantiated by more recent published data and experience. This, it was decided that part of the task of assessing hybrid benefits should also involve adjusting the earlier figures for FMVSS 214 and ECE 95 in line with more recent expectations.

Relevant Assumptions

A number of revised assumptions were agreed to for determining the likely benefits of a hybrid side impact regulation for Australia, as well as more recent expectations for the existing two dynamic side impact standards FMVSS 214 and ECE 95 and these are outlined below.

1. Each of the standards require a test at a crash severity of around 27km/h which will provide benefits at crash speeds up to 64km/h. No benefits are assumed above this speed.
2. The benefits will apply equally to both car-to-car and car-to fixed-objects in side impact collisions.
3. The benefits will apply equally to occupants involved in both non-compartment and compartment struck side impacts.
4. Near-side occupants who sustain AIS 5 or 6 fatal head injuries are excluded from any benefit from the standards. Reductions in chest injuries to occupants who sustain a non-fatal head injury are included
5. All head injuries (to survivors) in side impacts from contact with the door panel are reduced by 2 AIS and face injuries by 1 AIS over the crash severity range of 0-64km/h. For EuroSID (and BioSID), an additional benefit of 2 AIS applies for head contacts with the side rails.
6. Benefits will apply to the chest, pelvis, femur, shoulder, upper extremity, head and face injuries caused by contact with the door panel, hardware or armrest. Internal organ benefits will vary depending on the test dummy used.
7. An incremental reduction in TTI or V*C on injuries to the chest from door contacts for near-side occupants can be expressed as a crash severity change.
8. The injury risk curves for TTI and V*C apply to the range of impact speeds for side crashes at severities less than 64km/h for injuries of AIS 3 or greater.
9. Forty-five percent of AIS 3-6 and 90% of AIS 1-2 chest injuries over the crash severity range of 0 to 64km/h are expected to be affected by a side impact standard, based on NHTSA pre-standard crash tests.
10. A reduction of AIS 2 in chest injuries is expected by the use of SID and TTI over the crash severity range and an AIS 3 reduction is expected by the use of EuroSID and V*C measures.
11. It was assumed that there is some heart benefits approximating 25% of that relevant to the hard thorax for SID and EuroSID but 50% for BioSID given its superior injury criteria and test performance.
12. New Australian test data show that V*C is a more critical parameter than TTI and this should lead to additional countermeasures to protect the abdomen. Thus, an overall injury reduction for abdominal injuries of AIS 3 for V*C from EuroSID across the relevant crash severity range is expected (no benefit was claimed for FMVSS214 as SID does not measure abdominal injury).
13. Only upper extremity injuries from contact with the door panel or hardware at or below the crash severity range are relevant. As no test data were available on the likely reductions in contacts, a modest AIS 1 injury reduction is assumed.
14. A dynamic side impact standard will result in the elimination of all injuries with exterior contacts for far-side occupants, ejected through the far-side door over the severity range of 0-40km/h.
15. As the European test procedure does not include a rear seat dummy, no rear seat benefit should be awarded to the ECE Reg 95 standard and similar benefits would apply to front and rear seat occupants in both FMVSS 214 and the proposed Hybrid test.

Results of the Analysis

A detailed system of spreadsheets was assembled for calculating the benefits of both the existing and hybrid standards. Relevance figures were assigned by body region and seating position (near- or far-side of the vehicle) and the subsequent Harm units removed were computed. The savings by body region and seating position were then summed to arrive at the total estimate of savings for both standards. Annual Harm saved was converted into Unit Harm benefits using both a 5% and a 7% discount rates with fleet life estimates of 15 and 25 years. The results of the analysis are shown in Table 1 below and discussed below for each of the three regulations.

Revised FMVSS 214.

The revised benefit estimate for the US standard, FMVSS 214, assuming that all vehicles in the Australian fleet were to comply instantaneously was A$116.2 million. This is 84.5% of the original figure previously published (A$136 million) essentially due to reductions in expected savings in abdominal, chest and head injuries because of revised performance criteria. This still yields a 3.7% reduction in vehicle occupant trauma annually if FMVSS 214 were to apply in Australia. The unit benefit per car would be between $116 and $145.60 per car, depending on the discount rate and fleet life figures used in the calculation. At $100 expected installation cost per vehicle, adopting this standard would still be cost-beneficial.

Revised ECE 95.

The equivalent revised figure for the European standard is A$121.6 million each year if all vehicles in the Australia fleet instantly complied. This is also only 83% of the figure originally estimated based on more recent evidence of performance expectations. It should be noted that most of the reduced Harm for the European standard comes from exclusion of any rear seat benefit because of the lack of a rear seat dummy (this was not anticipated at the original workshop held in Munich in 1994). On this basis, the unit Harm benefit would be somewhere between $121.40 and $152.40 per car, would still be cost-beneficial, and would yield a slightly higher reduction in occupant trauma annually of 3.9%.

Hybrid Proposal.

Finally, the hybrid proposal is expected to save A$141.7 million annually, based on the assumptions listed by the expert panel. This is 16.5% greater than ECE 95 and 22% greater than FMVSS 214 because of the expected more stringent test procedure, the inclusion of a rear seat dummy and the likely improvements from the use of BioSID test dummies. This would amount to an improved 4.5% reduction in vehicle trauma annually and with a unit Harm benefit of between $141.40 and $177.50 per car, would yield a Benefit-Cost-Ratio of 1.5 or greater. The hybrid proposal is clearly superior to either of the two existing standards and would overcome the difficulty of having different side impact standards in different continents.

Table 1: Summary Table of Harm Benefits for FMVSS 214 and ECE Reg 95.

Harmonised ECE 95

An alternative to the hybrid standard proposal outlined in this paper that might be a first step towards implementing the full hybrid proposal would be a modified ECE 95 regulation that included a rear seat EuroSID dummy. While not providing all the benefits expected with the hybrid standard, it would be a compromise over the two existing standards that might be acceptable to both regulation authorities.

It is difficult to know what additional benefits would accrue to the modified ECE 95 standard as limited current test results would suggest that most current cars would meet this requirement (see Ohmae, Sakurai, Harigae & Watanabe, 1989). Nevertheless, with a rear seat dummy installed in a ECE 95 test, some global improvement in rear seat protection might be expected as manufacturers respond to this requirement. Assuming a 15% improvement was achieved by this global improvement, the annual benefits in Australia would be A$129 million with a unit Harm saving of between $128.60 and $161.40 per car.

Recommendations

It is recommended, therefore, that the ATSB Road Safety take a lead in promoting the introduction of an international hybrid standard similar to that outlined by Seyer and Fildes (1996) by:

1. continuing to participate in international harmonisation and European Working Party meetings to gain international agreement for a single side impact regulation;
2. seeking to become involved in future research and discussions aimed at developing and improving further the proposed hybrid side impact standard;
3. examining the feasibility of Australia, Canada and possibly Japan working towards introducing the hybrid standard in these countries as a model for others to follow;
4. holding discussions with consumers groups such as the Australian New Car Assessment Program to investigate the possibility of the hybrid standard becoming the accepted side impact performance test in their evaluations; and
5. actively participate in other research effort aimed at reducing injuries in side impact crashes beyond regulation levels by developing injury reduction as a design criterion for new passenger cars manufactured and sold in this country.

Type: Research and Analysis Report

Sub Type: Consultant Report

Author(s): B Fildes, K Digges, D Dyte & K Seyer

ISBN: 0 642 25507 5

ISSN: 0810-770X

Topics: Economic, Occ protection, Vehicle design

Publication Date: 01/06/98