In most European countries, unprotected road users like pedestrians account for a significant proportion of the road accident casualties. This was recognized by the European Experimental Vehicles Committee and several studies in this field (EEVC 1982, 1984, 1985). Based on this research various recommendations for the front structure design of passenger cars were developed along with test methods and regulations to assess pedestrian protection.
In the spring of 1987 one of these proposals was discussed by the EEVC concluding that the basis of the proposal was promising however additional research was needed to fill up some gaps. The European Experimental Vehicles Committee was asked to coordinate this research and at the end of 1987 EEVC Working Group 10 was set up with the following mandate:
'To determine test methods and acceptance levels for assessing the protection afforded to pedestrians by the fronts of cars in an accident. The test methods should be based on sub-system tests, essentially to the bumper, bonnet leading edge and bonnet top surface.
The bumper test should include the air dam; the bonnet leading edge test should include the headlight surround and the leading edge of the wings; the test to the bonnet top should include the scuttle, the lower edge of the windscreen frame and the top of the wings. Test methods should be considered that evaluate the performance of each part of the vehicle structure with respect to both child and adult pedestrians, at car to pedestrian impact speeds of 40 km/h. The different impact characteristics associated with changes in the general shape of the car front should be allowed for by variations in the test conditions (e.g. impact mass and velocity, direction of impact)'
Section I: Pedestrian protection in Europe
EEVC WG10 started its activities in January 1988. Both governments (mostly represented by research institutes) and automobile industry were represented in the working group. A programme was set-up intended to develop the required test methods as described by the mandate.
The studies necessary to develop test methods were summarised in a first report of EEVC WG10 (1989). These development studies included full scale dummy tests, cadaver tests, accident reconstructions, analysis of accident data and computer simulations.
Furthermore the developed test proposals had to be tested against representative cars of current designs to determine the feasibility of the proposals. The compatibility with existing regulations, other safety features and basic operational requirements for cars was assessed under a contract to the European Commission and under the auspices of EEVC. The contract was completed in June 1991 and included an Annex called "Frontal surfaces in the event of impact with a vulnerable road user - proposal for test methods"
and was part of the second EEVC WG10 report, presented to the 13th ESV Conference in 1991.
The third and final report of EEVC WG10 was written in 1994 and focused especially on the changes and improvements with respect to the previous version of the proposed test methods described in reports from 1991, giving general background information and explaining the choices finally recommended. After that report, the Working Group 10 was dissolved.
The recommendation of EEVC WG10 defined four sub-system tests to assess pedestrian protection afforded by passenger cars:
• A legform to bumper test, performed in three locations of the vehicle bumper at 40 km/h with a legform impactor (13.4 kg) able to measure tibia acceleration and knee bending and shear. The proposed limit for tibia acceleration was 150g and those for knee bending and shear were 15º and 6 mm respectively.
• An upper legform to bonnet leading edge test in three locations of the bonnet leading edge with an upper legform impactor at impact conditions (mass up to 17 kg, velocity up to 40 km/h) depending on the vehicle geometry, able to measure femur force and bending. The acceptance limits were a total force in the femur of 4 kN and a bending moment of 220Nm.
• A child headform (2.5 kg) to bonnet top test at 40 km/h in nine locations of the front part of the bonnet, measuring head lineal acceleration to compute the Head Injury Criteria (HIC). The acceptance level for the nine tests was HIC below 1000.
• An adult headform (4.8 kg) to bonnet top test at 40 km/h in nine locations of the front part of the bonnet, measuring head lineal acceleration to compute the Head Injury Criteria (HIC). The acceptance limits for the nine tests was HIC below 1000.
HIC
Formula 1-1: Head injury criterion definition.
In May 1997 the former members of EEVC WG10, on request of the EEVC Steering Committee, met again to discuss technical progress and new developments with respect to the EEVC pedestrian protection test methods. Based on these discussions the Steering Committee decided in June 1997 to set-up a new EEVC working group -WG 17 Pedestrian Safety to review of the EEVC WG10 test methods (final report 1994) and propose possible adjustments taking into account new and existing data in the field of accident statistics, biomechanics and test results. Between October 1997 and November 1998 more than 100 documents were presented, analysed and discussed in six WG17 meetings, including inputs from several organisations, including ACEA, JARI and JAMA.
More recent accident statistics were analysed, showing among other findings a decrease in the proportion of injuries caused by the bonnet leading edge of modern streamlined passenger cars and that the windscreen and A-pillars of these cars are important injury areas, not covered by the EEVC test methods.
Biomechanical tests were analysed and additional accident reconstructions were performed, deriving injury risk functions, especially for leg and pelvis injuries. This resulted in an increase of the acceptance levels for the upper legform to bonnet leading edge test.
In parallel to this process, in 1997 the recommended EEVC WG10 procedures on pedestrian safety were also included in the test matrix that EuroNCAP programme performed in order to rate vehicle safety features of the European fleet. This inclusion in a consumer programme was the perfect platform to extensively prove the proposed test methods but also to get a first overview of how far were the current car design to a pedestrian-friendly vehicle. The first results on the vehicle performance were not very positive regarding pedestrian protection but boost research on pedestrian friendly solutions in passenger cars, rising to the top research issues pedestrian protection.
In both forums the pedestrian sub-system tests have been extensively evaluated and improved and EEVC WG17 has included in its report many improvements in these sub-systems. The final recommendation of EEVC WG17 (2002) included the following tests:
• A legform to bumper test, performed in three locations of the bumper, with an improved legform impactor (13.4 kg) at 40 km/h, able to measure tibia acceleration and knee bending and shear. The acceptance levels of this test were those from EEVC WG10; that is tibia acceleration less than 150g, knee bending less than 15º and knee shear less than 6mm. As this test is representative for a complete
Section I: Pedestrian protection in Europe
dummy test if the bumper impact occurs at or below the knee joint, an alternative horizontal upper legform test (9.5 kg) is proposed with an impact speed of 40 km/h, when the lower bumper height is more than 500 mm above the ground. In this case, 5.0kN and 300Nm are the maximum acceptance levels for femur force and bending respectively.
• An upper legform to bonnet leading edge test (three impact locations) with an upper legform impactor at updated impact conditions (mass, velocity and angle) depending on the vehicle geometry, able to measure femur force and bending.
The impact energy curves were updated, based on the results of computer simulation studies, indicating lower impact energy for streamlined vehicles, readjusting also the velocity look-up curves in order to prevent the mass being less than the practical lower limit of 9.5 kg. Due to these updates, the acceptance limits were increased to 5.0 kN of maximum force and 300Nm for maximum bending.
• A child headform, build with a new material to improve durability and avoid vibrations, (2.5 kg) to bonnet test at 40 km/h and impact angle of 50º (with respect the ground reference level) in nine locations of the front part of the bonnet (refined definition to avoid overlapping with the upper legform impact area) measuring head lineal acceleration to compute the Head Injury Criteria (HIC) and acceptance levels of HIC below 1000.
• An adult headform (4.8 kg), build with a new material to improve durability and avoid vibrations, to bonnet top test at 40 km/h and impact angle of 65º (with respect the ground reference level) in nine locations of the rear part of the bonnet (refined definition to avoid windscreen impacts), measuring head lineal acceleration to compute the Head Injury Criteria (HIC) and acceptance levels of HIC below 1000.
These final recommendations were adopted in EuroNCAP from January 2001 and were the basis for the COM to define the EC Directive on pedestrian protection, 2003/102/EC;
however, as EEVC WG17 requirements were very stringent, a two stages Directive was proposed. Both stages utilised the same test procedures developed by the EEVC, but the injury limits for Stage 1 were less stringent than those from EEVC WG17, to be applied in Stage 2.
Despite the fact that the technical requirements for 2003/102/EC were only finalised after many years of discussion and negotiation, and numerous cost/benefit and feasibility studies, many vehicle manufacturers were still of the opinion that compliance with the Stage 2 limits (in fact EEVC WG17 requirements) was not feasible. For this reason, 2003/102/EC included a review clause on the feasibility of the Stage 2 limits, with the review to be undertaken using data gathered during testing to the Stage 1 requirements.
The Stage 1 of the Directive 2003/102/EC came into force in 2004, applying all vehicles with category M1, of a maximum mass not exceeding 2,5 tonnes, and N1 derived from M1, of a maximum mass not exceeding 2,5 tonnes.
The requested requirements were:
• Mandatory lower legform to bumper test. The test procedure is identical to the one defined by EEVC WG17 but the acceptance level are relaxed, allowing tibia acceleration up to 200g, knee bending angle up to 21º and a knee shear up to 6 mm. If the lower bumper height is above 500 mm, the upper legform to bumper test is performed instead at an impact speed of 40 km/h with a maximum femur force of 7.5 kN and bending moment not exceeding 510 Nm.
• Mandatory headform to bonnet test. The test procedure proposed by the EEVC WG17 is used reducing the impact energy by using an intermediate child/small adult headform of 3.5 kg impacting the bonnet top at 35 km/h in free flight. The acceptance level is set to HIC less than 1000 in 2/3 of the bonnet areas impacted and less than 2000 in the rest 1/3.
• Monitoring adult headform to bonnet and windscreen test. The adult headform test procedure suggested by the EEVC WG17 is extended to the windscreen area, reducing the speed to 35 km/h maintaining the 4.8 kg headform but for monitory purpose only. The acceptance level is set to HIC less than 1000.
• Monitoring upper legform to bonnet leading edge test performed at speed up to 40 km/h. The same procedure proposed by EEVC WG17 is adopted with monitory purpose only with acceptance levels of a maximum of 5.0 kN of femur force and a maximum of 300 Nm of femur bending.
The review on the feasibility of the Stage 2 limits was concluded in 2007 and, as a result, a number of relaxations to the Stage 2 limits were proposed. To offset these relaxations and to ensure that the reductions in pedestrian fatalities and injuries predicted for the original Stage 2 limits were still achieved, the European Commission proposed as an alternative make mandatory the fitment of Brake Assist systems, as the capacity of assisting the driver in achieving the maximum achievable deceleration in a braking situation has shown to have significant benefits in terms of pedestrian protection.
Moreover, to also contribute to this objective, the scope of the directive was extended to cover vehicles of categories M1 and N1 with Gross Vehicle Weight (GMW) above 2500 kg. These two types of vehicles are only exempted to meet Phase 1 and Phase 2 requirements if the driver's R point is either forward of the front axle or longitudinally rearwards of the front axle transverse centre line by a maximum of 1100 mm.
The Commission proposed that these revised pedestrian protection requirements should be published in a new EC Regulation which would repeal and replace the existing EC
Section I: Pedestrian protection in Europe
Directive on pedestrian protection (2003/102/EC) and the related EC Directive on frontal protection systems (2005/66/EC). This new regulation, (2009/78/EC) that introduced revised Stage 2 limits and mandated the fitment of brake assist systems was published on 4th February 2009 and is also formulated in two steps approach to be consistent with the directive it replaced. Phase 1 of this 2009/78/EC is identical to 2003/102/EC and the updates are done in the phase 2 requirements. This 2009/78/EC regulation proposed the following test in the phase 2 along with requirements for the mandatory fitment of Brake Assist systems:
• Lower legform to bumper test performed with the EEVC legform impactor (13,4kg) at 40 km/h in three locations of the bumper and measuring tibia acceleration and knee bending and shear. The acceptance level for these tests were a tibia acceleration less than 170 g, a knee bending less than 19º and a knee shear less than 6 mm. In addition, the manufacturer may nominate bumper test widths of up to 264 mm in total where the acceleration measured at the upper end of the tibia shall not exceed 250 g.
• If the lower bumper height is above 500 mm, the upper legform to bumper test is performed instead at an impact speed of 40 km/h with a maximum femur force of 7.5 kN and bending moment not exceeding 510 Nm.
• Mandatory child/small adult headform to bonnet test. The test procedure proposed in the Stage 1 is maintained with a child/small adult headform of 3.5 kg impacting the bonnet at 35 km/h.
• Mandatory adult to bonnet test. The monitoring test proposed in Stage 1 is again restricted to the bonnet area, performing the test at an impact speed of 35 km/h using a 4.5 kg test impactor instead that a 4.8 kg headform.
• For both type of tests, the HIC recorded shall not exceed 1000 over one half of the child headform test area and, in addition, shall not exceed 1000 over 2/3 of the combined child and adult headform test areas. The HIC for the remaining areas shall not exceed 1700 for both headforms.
• Monitoring upper legform to bonnet leading edge test, performed at impact speed up to 40 km/h. The proposed EEVC WG17 procedure is adopted with acceptance levels equal to those to Stage 1, maximum of 5.0 kN of femur force and a maximum of 300 Nm of femur bending.
Taking into account the process as a whole and considering the time frame in which this thesis has been developed, it has been used as basis the EEVC WG17 recommended test procedures. This option has been supported on the fact that these were the tests used in EuroNCAP for rating and classifying vehicles according their pedestrian
friendliness but also because the different modification of the Directive have been based on the requirements to be set to approve the test rather than on the test procedure itself.