CR 165: Benefits of a Frontal Offset Regulation (1996)
Australian vehicles are currently required to meet Australian Design Rule ADR 69 which specifies head, chest and femur dummy criteria in a dynamic full frontal crash test at 48km/h. This is based on the US regulation FMVSS 208 with the added allowance for the test dummies to be restrained by seat belts.
The European road safety community has been working towards developing a dynamic frontal offset standard to be mandated for all European vehicles towards the end of 1998. The ATSB Road Safety is participating in this work with a view to adopting this new regulation if warranted. The question arises whether there would be sufficient additional benefits to Australian motorists in addition to ADR 69 and whether they would be cost-effective.
This study was commissioned by FORS to address this question. The tasks included an examination of the pattern of injuries sustained in offset compared with full frontals as well as a Harm analysis to calculate the likely benefits of the proposed EEVC offset requirement.
Proposed European Offset Standard
The proposed EEVC offset requirement specifies a range of head, neck, chest, femur and lower leg criteria for two Hybrid III test dummies situated in the front seat of a passenger car impacting a deformable face fixed barrier offset 40% on the driver's side.
The injury criteria specified for the dummies are more comprehensive than those currently applying in ADR 69 or FMVSS 208 and importantly includes lower leg injury criteria. This is really a first and an important break through for occupant protection. A number of studies have reported lower leg injuries are frequent in frontal crashes and while not necessarily life threatening, nevertheless, are often disabling and extremely painful requiring considerable rehabilitation and very costly to the community in general.
In addition to lower limb criteria, the proposed EEVC offset requirement also includes neck injury criteria and more comprehensive head and chest requirements. Moreover, the standard is likely to lead to structural improvements in cabin integrity which will benefit car occupants.
Injuries In Offset Crashes
The first task undertaken was an analysis of the Crashed Vehicle File at MUARC, a database containing details of over 500 crashes and 600 hospitalised passenger car occupants. Of these, 215 were frontal crashes where the driver sustained a lower leg injury, roughly equally divided between full frontal and offset configurations.
The analysis revealed that the outcome for drivers involved in near-side offset collisions was considerably worse than for equivalent full frontal drivers. They sustained more severe injuries, especially to the lower torso and the legs than their counterparts in full frontal crashes and, on average, at lower impact speeds. This was not a function of differences in seat belt wearing,rates but did appear to be influenced slightly by the type of car they were travelling in.
Lower limb injuries and severe injuries to the upper limbs seem to be areas requiring particular attention in near-side offset collisions (that is, when the offset crash was on the same side of the vehicle as the driver). Reduced intrusion inside the passenger compartment by the steering column, instrument panel, A-pillar and floor and toepan need greater emphasis in near-side offset frontal crashes for drivers.
Estimating Injury Reductions
As there were no injury data available and very few test results, an expert panel was formed comprising international specialists from vehicle manufacturing, research organisations, and government agencies responsible for vehicle safety.
From a one-day workshop held in Washington DC in December 1995, a number of assumptions were developed on which to calculate the likely injury reductions of the offset standard by body region. The expert panel were unanimous in their view that the benefits would be derived from three sources, namely from a general improvement in structural integrity (the so-called universal benefit), from a greater use of driver side airbags, and from specific countermeasures to address particular injuries such as those to the lower legs.
It was especially noteworthy that there was a high degree of consensus among the expert panel of the need for such a standard and likely injury reductions that would accrue. There was also a strong call from many of these organisations for a single worldwide offset standard to ensure the best possible outcome for vehicle occupants.
The Harm Redcuation Method
A Harm analysis was then performed using these assumptions as a basis for calculating the likely Harm saved by the EEVC proposed offset standard. The Harm Reduction method developed by the Monash University Accident Research Centre in conjunction with Dr. Kennerly Digges for previous benefit studies was again used here.
The national Harm database developed previously (e.g. Monash University Accident Research Centre, 1992; Fildes, Digges, Carr, Dyte & Vulcan 1995) was the basis for calculating the benefits of the proposed EEVC offset standard. Allowances were made for subsequent vehicle safety improvements such as ADR 69 in arriving at these benefits.
Analysis by body region was undertaken using a 3-step cascading model. Harm saved from the universal benefit was first deducted, followed by increase in airbag usage (up to 100%) and finally specific countermeasure benefits. Given that the likely usage rate of driver airbags in 1998 was unknown, these benefits were calculated for a range of possible usage rates from 70% to 100%.
The benefits of adopting the proposed EEVC offset standard were expressed as both the annual Harm saved assuming all vehicles in the fleet were compliant as well as the unit Harm benefits per car across its lifetime. In computing unit Harm benefits, 5% and 7% discount rates were employed for 15 year and 25 year life of the vehicle periods.
Annual Harm Benefits
The annual Harm reduction that would accrue from the offset standard in addition to that achieved from ADR 69 was estimated to be at least A$297 million (a 15% reduction in frontal Harm) and at best, A$460 million (a 23% reduction in frontal Harm). The full benefits would apply when all vehicles in the fleet complied with both standards.
Unit Harm Benefits
Unit Harm benefits (the average savings per car across its lifetime) were then calculated using 5% and 7% discount rates and life of the vehicle periods of 15 and 25 years. These calculations showed that unit Harm savings from adopting the EEVC offset requirement would be somewhere between A$296 and A$576 per car. In other words, the break-even cost for having to meet this new requirement is likely to be somewhere in this range.
It should be noted that the most conservative estimate was for a 15% reduction in frontal Harm attributed directly to this standard assuming no benefit from increased airbag use. This would seem to be a worthwhile improvement in occupant protection alone. The minimum break-even cost to achieve this benefit would be A$296 per vehicle which seems feasible in light of industry estimates which suggest a A$100 additional cost for achieving the side impact standard improvements outlined in Fildes et al, (1995).
On the basis of the evidence presented here, it would seem desirable for Australia to consider introducing an offset frontal crash standard similar to that being proposed in Europe. The benefits likely to accrue would be somewhere between A$297 million and A$460 million annually with 100% fleet compliance. The break-even cost per car across its lifetime would be on average from A$296 to A$576. This finding is conditional on all aspects of the EEVC proposal outlined here and is likely to be severely compromised if any of the injury criteria were to be removed or downgraded over that currently proposed.
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Type: Research and Analysis Report
Sub Type: Consultant Report
Topics: Economic, Occ protection, Vehicle design
Publication Date: 01/06/96