Assessment of Pedestrian Protection Afforded by Vehicles in Australia

Michael P. Paine
Vehicle Design & Research Pty Ltd

Christopher G. Coxon
Transport South Australia

Presented at Impact Biomechanics & Neck Injury 2000.
Institution of Engineers Australia
Sydney, March 2000

Keywords:
Pedestrian safety, consumer testing, head injury, leg injury

ABSTRACT: Pedestrians account for 18% of Australian road fatalities. Ways to reduce this toll through improved frontal design of vehicles have been hampered by a lack of objective tests to simulate pedestrian impacts. The European Experimental Vehicles Committee therefore developed a series of tests to assess impacts to the head, upper legs and lower legs of pedestrians. The European New Car Assessment Program (Euro-NCAP) incorporated these tests in its crash test program in 1996. During 1999 the Australian New Car Assessment Program aligned its test program with Euro-NCAP. Pedestrian protection tests of several Australian vehicles recently commenced at the Road Accident Research Unit of the University of Adelaide. This paper describes the tests and rating system now used by Australian NCAP for assessing pedestrian protection.
 

Updates:


1. Introduction

1.1 Pedestrian Injury Statistics

In the 12 months ending June 1999 there were a total of 324 pedestrian fatalities and 2784 pedestrians hospitalised in Australia [1]. Pedestrian fatalities account for 18% of all Australian road fatalities. This compares with 13% in the USA, 28% in the UK and Japan and 16% averaged across European nations [2].

Pedestrians struck by the front of a vehicle account for 84% of pedestrian fatalities and therefore 15% of all road fatalities in Australia. Head injuries, most of which involved impacts with the vehicle, were the cause of death in two-thirds of the fatalities [1, 3].

1.2 Regulations and standards

There are no Australian regulations which apply specifically to the pedestrian 'friendliness' of vehicles. Australian Design Rule 42/ "General Safety Requirements" refers, in general, to the injury potential of equipment fitted to vehicles but does not set performance requirements.

In the late 1980s the European Experimental Vehicles Committee (EEVC) began to develop a set of standards that would minimise serious injury to pedestrians in impacts up to 40 km/h. In 1991 EEVC proposed a set of component tests representing the three most important mechanisms of injury: head, upper legs and lower legs (see Section 2 for further details). This work was incorporated in the consumer tests conducted by Euro-NCAP with the first results published in 1997.

Early in 1999 the European Commission (EU) announced that it planned to introduce regulations to make the EEVC requirements mandatory within a few years.

1.3 Developments in Australia

Research on the influence of car design on injuries to pedestrians has been conducted since at least the 1970s [3,4]. Several projects have endeavoured to investigate the influence of bull bars on pedestrian kinematics and injuries [5,6].

In the late 1990s the Road Accident Research Unit of the University of Adelaide developed free-flight headform tests to evaluate the injury potential of vehicle fronts [7]. This work was supported by the Federal Office of Road Safety.

Using the new facilities, several designs of bull bar were compared with the unmodified front of a popular large four-wheel-drive vehicle. An innovative foam plastic device to protect the vehicle from damage by wildlife was also tested and compared favourably against metal bull bar designs [8].

In February 1999 the International Harmonised Research Activities Pedestrian Safety Working Group met in Adelaide. Research results were presented at a seminar that followed the meeting [2]. This included detailed discussion about the EEVC component tests for assessing pedestrian protection.

Also during 1999 the Australian New Car Assessment Program (ANCAP) aligned its crash test and assessment procedures with those of Euro-NCAP, including the EEVC pedestrian test protocol. The first ANCAP tests to this protocol began at the University of Adelaide this year. Results from that test series should be available in May 2000.

1.4 Overseas Developments

The Japanese NCAP organisation OSA intends to introduce the EEVC pedestrian tests into its consumer test program.

Honda has developed pedestrian impact simulation software [9] and a full scale adult dummy (POLAR) for use in impact research [2]. McLean [4] points out there are several difficulties with the use of full dummy tests in regulations and standards.

The US National Highway Traffic Safety Administration (NHTSA), which pioneered consumer crash tests, is looking at the need for pedestrian protection tests but, apparently, has not yet committed to the EEVC protocol.

Pedestrian protection requirements are being considered in the United Kingdom [10].

2 Test Procedures

2.1 Test Description

This section provides a general description of the EEVC procedures, as now used by ANCAP. A more detailed description of the procedures and test equipment is given in references 11, 12 & 13.

The procedures require determination of locations that are most likely to be injurious and those that are least likely to be injurious. The vehicle manufacturer may nominate the latter cases, provided that they are not too close to locations judged to be injurious.

2.2 Three Sub-system Tests

The EEVC procedures require three sub-system tests that simulate impacts by the head, upper leg and knee/lower leg. At the Adelaide seminar it was stressed several times that any assessment must be based on all three tests because the design of a vehicle simply to meet one of the requirements could lead to a degradation of protection for another area.

2.3 Lower Leg

This test simulates injuries that a pedestrian may have with the soft tissue injuries to the knee joint or fractures to the adjacent leg bones. These happen early in the pedestrian strike.

Figure 1. EEVC Lower Legform Test


The test device simulates the human lower leg, including the knee joint. The impact occurs side-on to the plane of articulation of the knee. The angular movement of the knee joint at right angles to the axis of articulation is measured. Tibia deceleration and knee shear displacement are also measured.

Three impact tests are conducted, one in each of three equal transverse zones across the vehicle. The impact locations in two of the zones are chosen for highest injury potential (generally the stiffest structure). The least harmful location is chosen for the third zone.

Euro-NCAP assigns a red (poor) rating if the tibia acceleration exceeds 230g, the knee shear exceeds 7.5mm or the knee bending angle exceeds 30 degrees.

2.4 Upper Leg Impacts

This simulates impacts that are frequently associated with fractures to the femur and pelvis. This impact takes place later than the lower leg impact, and in the test, the impactor representing the upper leg strikes the leading edge of the bonnet.

Figure 2. EEVC Upper Legform Test


The test device simulates the upper leg with a covering of elastomeric foam, the equivalent to leg flesh. When it strikes the bonnet leading edge the leg can rotate around a friction loaded pivot.

The procedures prescribe a minimum impact energy, based on the height of the bonnet leading edge (BLE) and the forward projection of the bumper ('bumper lead').

Three impact tests are conducted, one in each of three equal transverse zones across the vehicle. The impact locations in two of the zones are chosen for highest injury potential (generally the stiffest structure). The least harmful location is chosen for the third zone.

Bending moments and resultant forces are measured. Euro-NCAP assigns a red (poor) rating if the bending moment exceeds 400Nm or the resultant force exceeds 7kN.

2.5 Head Impacts

Typically the head impacts with the bonnet after the lower and upper leg contact, with the head pitched down onto the bonnet top.

Two headforms are used to simulate this type of head impact: an child headform with a mass of 2.5 kg and an adult head form with a mass of 4.8 kg. The child headform strikes are to the front of the bonnet (wrap-around distance 1 to 1.5m ) while the adult headform strikes are to the rear of the bonnet or beyond (wrap around distance 1.5 to 2.1 m).

Figure 3. EEVC Child Headform Test.
Six tests are conducted with each headform, based on three equal transverse zones and two impacts within each zone. One impact location is chosen for highest injury potential, such as above engine parts, suspension mounting points or bonnet hinges. The other is chosen to be the least injurious. Where the left and right zones have similar structures judged to be the most injurious the next worst location is chosen for one of the zones.

If between one third and two thirds of a test zone for the adult headform test is found to be within the windscreen area then three default scores are assigned for the windscreen/a-pillar: one poor (a-pillar) and two good (glass away from dash) giving a score of 4. This is added to the three scores for impact tests to the bonnet. The impact locations in two of the bonnet zones are chosen for highest injury potential. The least harmful location is chosen for the third zone.

If more than two-thirds of the adult headform test zone is within the windscreen then only one impact test is usually conducted. Five default scores are assigned: two poor (a-pillars) and three good (glass, away from dash) giving an adult headform score of 6. This is added to the score for the single test that is chosen for the highest injury potential in the centre zone. This is generally located at the lower centre of the windscreen where the headform is likely to contact the dash through the glass.

Accelerometers in the headform are used to determine Head Injury Criterion (HIC). Euro-NCAP assigns a red (poor) rating if the test results in a HIC of 1,500 or more (HIC36 is assumed but the deceleration curve is typically a spike of less than 8ms duration).

3 Assessment of Test Results

3.1 Injury Measurements

Under the Euro-NCAP Assessment Protocol, each impact is assigned a score based on the injury measurements. The scoring system is summarised in Table I. Two injury values are prescribed. The 'good' value earns a maximum of two points for that impact and a 'poor' value earns zero points. A 'sliding scale' applies for intermediate points. For example, a HIC of 1300 would earn ((1500-1300)/(1500-1000)*2 = 0.8 points.

Where more than one injury measurement is taken for an impact the value with the worst score is used in the analysis.

Table I. Assessment of Pedestrian Impact Tests

Type of test Injury Measurement Units Good (2 pts) Poor (0 pts)
Child Headform Head acceleration HIC <1000 >=1500
Adult Headform Head acceleration HIC <1000 >=1500
Upper Leg Bending moment Nm <220 >=400
Sum of forces kN <4 >=7
Lower Legs Tibia acceleration g <150 >=230
Knee shear displacement mm <6 >=7.5
Knee bending angle degrees <15 >=30
 
 

3.2 Overall score and stars

The scores for each impact are summed to give an overall score. Table II shows the maximum possible score for each test. The maximum overall score is therefore 36 points.

Table II. Test Scores

Type of test Impact Locations Max Score
Child Headform 6 12
Adult Headform 6 12
Upper Legform 3 6
Lower Legform 3 6
 
A star rating is assigned from the overall score.
27.5 or more 4 Stars

18.5 to 27.49 3 Stars

9.5 to 18.49 2 Stars

0.5 to 9.49 1 Star

Less than 0.5 Zero Stars

(This list incorporates a rounding process described in the Euro-NCAP protocol).

3.3 Typical Euro-NCAP scores

Appendix A sets out the results of an analysis of 14 Euro-NCAP pedestrian assessments. The mean overall scores of 11.01 for passenger vans and 9.75 for small cars correspond to the low end of a 2-Star rating. Upper leg scores were particularly poor. 'Default' adult head scores of 6 or 8 applied to most of the passenger vans - probably due to their short bonnet lengths.

Of the 12 'family' cars assessed by Euro-NCAP one was awarded one star and the remainder were awarded 2 stars. In recently released results for 'super-minis' all seven vehicles were awarded 2 stars. So far no vehicle has earned more than 2 stars.

4 Improvements to Vehicle Design

Changes to the design of vehicle fronts are discussed in references 4, 8 11, 12 and 14. Lawrence [12] notes that "...solutions to the problem of achieving better pedestrian safety are often readily available, low cost and could be applied over a higher proportion of the car surface". This appears to contradict Clemo [15] from MIRA: "It appears that cars will need to undergo profound changes in design to meet the required standard". However, the MIRA research involved existing vehicle models.

Lawrence makes the point that relatively simple changes to detail in the early design stages of a new model can lead to major improvements in pedestrian protection. Several of his tips are discussed below.

4.1 Front bumper

A deeper profile to support the leg-form is a possible solution, or to provide a secondary support bar below the bumper would reduce pitching of the leg-form and bending of the knee joint.

The bumper needs localised compliance and then efficient energy absorption. Foam plastics are available to achieve this aim, together with recovery characteristics that minimise damage during low speed car-to-car collisions. The deformed profile of the vehicle during the impact needs to be considered. Spoilers and similar low-mounted, compliant structures can help to reduce the loads on the lower legs.

4.2 Headlamps

As the headlamps change from glass to plastic the hardness of the headlamp will change significantly, reducing the possibility of causing severe pedestrian injury. But to maintain good lamp alignment, the mounting must be stiff and not subject to vibration, which will require some development to meet the overall requirements.

4.3 Bonnet leading edge

There is scope for reducing the stiffness of components at the leading edge of the bonnet. Improvements include moving the location of the bonnet latch rearward, or to the sides and moving transverse stiffeners back from the leading edge of the bonnet.

Crush depths, under test, of between 65mm and 150mm are appropriate, depending on geometry.

4.4 Bonnet and fender tops

Redesign of the top of fenders and the fender-bonnet edges that allows room for crush to limit injury is essential. Head-form contact with the hard seam generally located at the edge of the panel results in high head impact forces. Use of energy absorbing structures such as sandwich structure is one possibility.

Improvements include increasing under-bonnet clearances, locating softer components at the top of the engine and avoiding localised stiffness of the bonnet in favour of a more distributed structure. A bonnet which wraps around the sides of the car would have advantages (for example, the E-type Jaguar).

Crush depths (under test) of 80 to 90 mm for the adult headform appear appropriate.

5 Benefits and costs

The UK Department of Environment, Transport and the Regions estimates that improved vehicle design, in accordance with proposed EU requirements, should reduce pedestrian fatalities by 10% after three years and 20% after 8 years [10].

The DETR estimate may be optimistic: the UK Transport Research Laboratory (TRL) has estimated that 8% of all pedestrian fatalities and 21% of all pedestrian serious injuries could be prevented through improved vehicle design [2, 12].

McLean [3] points out that Australia may have more to gain from pedestrian friendly vehicle designs because urban traffic speeds are generally higher in Australia and a greater proportion of pedestrian accidents are likely to take place at the impact speeds simulated in the EEVC procedures.

As indicated above, there is wide variation between the TRL and industry in the estimated costs of compliance with the proposed requirements [16]. Looking at the longer term, when pedestrian friendliness is taken in to consideration in the early stages of the design process, then the TRL cost of compliance estimates are considered to be reasonable.

Using conservative values for injury reduction, TRL estimates that the benefit/cost ratio of potential improvements would exceed 7 to 1 [2, 4, 12].

6 Implementation

Experience over the last two decade suggests that introduction of road user protection initiatives is expedited if they are incorporated in consumer test programs (see Table A2, Appendix A). In some cases, the regulation test is less severe than corresponding consumer test. Furthermore it takes time for penetration of new initiatives into the Australian vehicle fleet. It will take ten years for at least half of the fleet to comply with a new regulation and six years for at least half of the annual kilometres travelled to be in vehicles which comply with a new regulation.

7 Conclusions

Pedestrians struck by the front of a vehicle account for 15% of all road fatalities in Australia.

Test procedures have been developed in Europe to evaluate the pedestrian friendliness of vehicle fronts. The people conducting these tests in Europe have concluded that relatively simple changes to detail can lead to major improvements in pedestrian protection. These changes can be cost-effectively introduced if they are taken into account early in the design stage of a new model.

Consumer tests conducted by Euro-NCAP reveal that there is room for a great deal of improvement with current vehicle models. The situation is likely to be similar in Australia, where ANCAP has recently commenced testing to the Euro-NCAP pedestrian protection protocol.

References

1. Coxon, C. G. 1999, 'Safer Cars for Pedestrians', Proceedings of Road Safety Conference, Perth, November 1999.
2. Paine, M. P. 1999, Protecting pedestrians by Vehicle Design, unofficial report on an international seminar held in Adelaide in February 1999. Copy at: http://www1.tpgi.com.au/users/mpaine/ppvd.html .
3. McLean J. 1996 Pedestrian Friendly Vehicle Front Structures. A Review of the Research Literature, CR166, Federal Office of Road Safety, Canberra, July 1996.
4. Fisher, A.J. and Hall, R.R. 1972 'The Influence of Car Front Design on Pedestrian Accident Trauma'. Accident Analysis and Prevention 4, pp47-58.
5. Chiam H. and Tomas J. 1980 Investigation of the effects of bull bars on vehicle-pedestrian collision dynamics, Federal Office of Road Safety CR 13, October 1980.
6. Reilly-Jones C. and Griffiths M.J. 'The Effects of bull bars on pedestrian injury mechanisms and kinematics, Proceedings of the 15th International Technical Conference on the Enhanced Safety of Vehicles, Melbourne, Australia.
7. Streeter L., Anderson R., McLean J. and Garrett M. 1998 'Pedestrian Head Impact Testing at the University of Adelaide', Proceedings of the 16th International Technical Conference on the Enhanced Safety of Vehicles, Windsor, Canada.
8. Anderson R. and McLean J. 1998 'Crashworthiness Research at the Road Accident Research Unit', Proceedings of the Developments in Safer Motor Vehicles Seminar, Staysafe, March 1998.
9. Yoshida S. 1998 'Computer Simulation System for Car-Pedestrian Accident', Proceedings of the 16th International Technical Conference on the Enhanced Safety of Vehicles, Windsor, Canada.
10. DETR 1997 Road Safety Strategy: Current Problems and Future Options. Government report, October 1997.
11. Jansenn E. 1996 'EEVC Test Methods to Evaluate Pedestrian Protection' Proceedings of the 15th International Technical Conference on the Enhanced Safety of Vehicles, Melbourne, Australia.
12. Lawrence G. and Hardy B. 1998 'Pedestrian Safety Testing Using the EEVC Pedestrian Impactors', Proceedings of the 16th International Technical Conference on the Enhanced Safety of Vehicles, Windsor, Canada.
13. Spencer S., Anderson R., Streeter L. and McLean J.2000, 'Pedestrian Sub-system Testing in Australia', Proceedings of Impact Biomechanics Conference, Institution of Engineers Australia, Sydney, March 2000.
14. Haley J. 1994 'Pedestrian Friendly Vehicle Design', Proceedings of Bull Bar Safety Workshop, Institution of Engineers Australia, Sydney, may 1994.
15. Clemo K., Davies R. and Keys S. 1998 ' The practicalities of engineering cars for pedestrian protection', Proceedings of the 16th International Technical Conference on the Enhanced Safety of Vehicles, Windsor, Canada.
16. Cesari D., Fontaine H. and Lassare S. 1996 'The Validity of the Proposed European Pedestrian Protection Procedure and its Expected Benefits, Proceedings of the 15th International Technical Conference on the Enhanced Safety of Vehicles, Melbourne, Australia.
Author Biographies

Michael Paine is a mechanical engineer with over twenty five years experience in the fields of automotive safety and vehicle construction standards. In 1990 he started an engineering consultancy and has worked on a range of vehicle-safety related projects including: consumer crash tests, child restraints, visual ergonomics, bus safety, vehicle inspections and assessment of vehicle defects.

Chris Coxon is a mechanical engineer who has worked in the aircraft industry in America and automotive industries in Australia. He has worked in road safety for 15 years and has been involved in the Australian New Car Assessment Program (ANCAP) since its first test in 1992. He has been chair of the ANCAP technical committee since 1994. ANCAP publishes relevant vehicle occupant protection information for buyers of new cars using the best biomechanical research and test protocols from international sources.

The views expressed in this paper are those of the authors and do not necessarily represent the views or policy of any organisation.

Appendix A
Table A1. Analysis of Euro-NCAP Pedestrian Assessments


MAKE & MODEL CHILD HEAD ADULT 

HEAD

UPPER 

LEG

LOWER 

LEG

O'ALL SCORE STARS
PASSENGER VANS
           
CHRYSLR.VOYAGER(E).99
0.36
6.00
0.00
0.00
6.36
1
MITSUBI.SPACEWAG(LHD).99
6.00
6.00
0.00
1.57
13.57
2
NISSAN.SERENA(LHD).99
2.95
8.00
0.00
4.00
14.95
2
PEUGEOT.806(LHD).99
1.36
6.00
0.00
0.24
7.60
1
RENAULT.ESPACE(LHD).99
2.68
6.00
1.01
2.00
11.69
2
TOYOTA.PICNIC(E).99
7.72
6.00
0.00
2.00
15.72
2
VAUXHALL.SINTRA(LHD).99
2.58
6.00
0.00
0.00
8.58
1
VW.SHARON(LHD).99
2.32
6.53
0.79
0.00
9.64
2
       
Mean
11.01
 
       
Std Dev
3.50
 
SMALL CARS
           
FORD.ESCORT(E).99
7.67
9.07
0.07
1.03
17.84
2
FORD.FOCUS(LHD).99
4.20
5.71
0.05
0.00
9.96
2
MERBNZ.A-CLASS(LHD.99
0.42
6.00
1.28
1.80
9.50
2
NISSAN.ALMERA(E).99
7.15
1.76
0.00
0.15
9.06
1
RENAULT.MEGAN(LHD).98
3.08
1.46
0.00
0.84
5.38
1
VAUXHALL.ASTRA(E).99
4.28
2.46
0.00
0.00
6.74
1
       
Mean
9.75
 
       
Std Dev
4.34
 

 

Table A2. Timing of Road User Protection Initiatives


Test Procedure
Procedures Developed
Consumer Tests
Australian Design Rules
Full frontal crash test USA: late 70s US NHTSA: 1978

ANCAP: 1992 

(56 km/h)

FMVSS 208 late 1970s (48km/h)

ADR 69/00 1995 (48km/h)

Offset crash test (40% frontal) EEVC: early 90s ANCAP: 1993 (60km/h)

IIHS: 1995 (64km/h)

ANCAP 1995 (64km/h)

EuroNCAP: 1996 (64km/h) 

ECE R94: 1998 (56km/h)

ADR73/00: 2000 for new models, 2004 for existing models (56km/h)

Side Impact (Moving barrier, 90 degree impact) EEVC: early 90s EuroNCAP: 1996 (50km/h)

ANCAP: 1999 (50km/h)

ECE R95: 1998 (50km/h)

ADR72/00: 2000 for new models, 2004 for existing models (50km.h)

Pedestrian Protection EEVC: early 90s EuroNCAP 1996 (40km/h)

ANCAP: 2000 (40km/h)

ECE ? 

ADRs ?