IMPROVER Final Report: Subproject 1 TREN-04-ST-S07.37022
IMPROVER Impact Assessment of Road Safety Measures for Vehicles and Road Equipment
Final Report
Subproject 1
Impact on road safety due to the increasing of sports utility and multipurpose vehicles
TNO, The Netherlands Organisation for Applied Scientific Research, Netherlands
BASt Federal Highway Research Institute, Germany TRL Transport Research Laboratory Limited, United Kingdom
VTI National Road and Transport Research Institute, Sweden
Chalmers University of Technology Göteborg, Sweden
UTAC, L'Union Technique de l'Automobile, du Motocycle et du Cycle, France
April 2006
1 IMPROVER Final Report: Subproject 1 TREN-04-ST-S07.37022 with the following partners: • TNO, The Netherlands Organisation for Applied Scientific Research, Netherlands (Authors: C. van der Zweep) • BASt Federal Highway Research Institute, Germany (Authors: C. Pastor, B. Bugsel and J. Gail) • Chalmers University of Technology, Göteborg, Sweden (Author: R. Thomson) • TRL Transport Research Laboratory Limited, United Kingdom (Authors: T. Brightman and T. Horberry) • UTAC, L'Union Technique de l'Automobile, du Motocycle et du Cycle, France (Authors : T. Martin) • VTI National Road and Transport Research Institute, Sweden (Authors: T. Turbell)
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1 Contents 1 Contents ...... 3 2 Executive Summary ...... 4 3 Introduction ...... 6 3.1 Background of the problem ...... 6 3.2 Objectives ...... 6 3.2.1 Definition of SUVs ...... 7 3.2.2 Data collection...... 7 3.2.3 Structural analysis ...... 8 3.2.4 Environmental issues ...... 8 4 Method and Results ...... 10 4.1 Definition of SUV...... 10 4.1.1 Unified SUV and MPV definition...... 10 4.2 Data collection ...... 12 4.2.1 Sales figures...... 12 4.2.2 National accident statistics ...... 12 4.3 In-depth accident analysis...... 15 4.4 Structural analysis...... 17 4.4.1 Measurement of structural parameters...... 17 4.4.2 Fleet safety analysis based on global vehicle properties...... 20 4.4.3 Geometrical approach fleet systems analysis ...... 24 4.4.4 SUVs and the Standards EN1317 and EN12767 ...... 28 4.5 Environmental issues...... 31 5 Outcomes of the project...... 34 5.1 Safety...... 34 5.1.1 SUV and MPV definition ...... 34 5.1.2 Sales numbers...... 34 5.1.3 Safety issues reported world wide...... 34 5.1.4 National statistics...... 35 5.1.5 In-depth analysis ...... 35 5.1.6 Structural analysis ...... 36 5.2 Environment...... 37 6 Conclusions...... 39 7 Recommendations and EC actions ...... 40 8 References...... 42
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2 Executive Summary Automobile manufacturers are offering a wider range of vehicle models in terms of body configurations. As one part of this, the growing number of Multi-Purpose Vehicles (MPV) and Sport Utility Vehicles (SUV) will lead to modifications of the European vehicle fleet. Accompanying this, the safety and environmental performance of these vehicles will not be in line with modern European passenger cars. The objective of this study was to gain insight and understanding of the safety and environmental issues for SUVs and MPVs on the European road network. Although there is a growing presence of SUVs in European traffic, there is a lack of objective analysis to indicate the impact of these SUVs. In this study a general definition was formulated to be able to identify SUVs and MPVs in the M1 class vehicles. Based on this definition sales figures from the EU15 countries, national statistics and in-depth accident cases have been extracted from appropriate databases. The in-depth cases and a detailed analysis of the structural differences provided insight into the structural differences between passenger cars and SUVs. The environmental performance differences were also investigated. The classification of vehicles according to their body shape is quite often used to categorise vehicles for crashworthiness or similar activities. Historically this classification has been introduced by car manufacturers. In this study, a suitable definition for the SUV and the MPV, based on the legal terminology of off-roaders, is formulated. The height predictor of 1600 mm should be evaluated on future vehicle models on possible advantages and disadvantages (like the effect on drag resistance) in close cooperation with the car industry. The limited classification of vehicle body types in sales data collections makes a simple extraction of the sales figures for SUVs difficult. However, from the available resources it was identified that the sales of SUVs (in terms of off-roaders) and MPVs were growing in recent years to respectively 5% and 15% in 2003 in EU15 countries. In particular it can be expected that the 2003 overall European sales levels of SUVs (5%) will increase by 2008 to an expected share of 8%. This increase in the EU15 countries should be further monitored and besides this, the sales numbers in the EU25 countries should be investigated. It would also be most helpful in future research that in sales numbers a clear distinction between passenger cars and SUVs could be made based on the proposed definition. National statistics from countries participating in the project (UK, G, NL, S, F) were collected and analysed for the rates of accident involvement of SUVs during recent years and the injury outcome associated with these accidents. It is shown that there is a slightly higher problem with SUVs in collisions with other road users as compared to collisions between other passenger cars and these road users. Based on expected fleet changes in the near future, this problem can however become more serious. There are no distinctive trends observable for the MPV car category. The in-depth accident collection and analysis were carried out to further understand the problems and attempted to quantify the magnitude of the issue. This study has shown that both geometrical incompatibility and stiffness/mass incompatibility appear to be a factor in the accidents observed.
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A review of ongoing European research projects also identified the differences between the SUVs and the other road users in terms of mass, structure and stiffness. This review concluded that a multi-step approach requiring minimisation of geometric variations and harmonisation of structural properties is necessary to gain better interaction and avoid overly stiff vehicles. These recommendations are similar to those already proposed by the Automobile Manufacturers Alliance. It is important to recognize that the observed problems can be avoided with the introduction of compatibility based safety requirements. These requirements are particularly of relevance for SUVs since the data shows that they are more of a safety risk than MPVs or other passenger cars. Activities like VC-Compat can be used to drive these solutions forward and it is recommended that their effect should be addressed in future research studies commissioned by the EC (within FP7 projects). Besides this, a review of the current test protocols for road equipment was studied. The current test vehicles employed to test roadside safety equipment were shown to poorly represent the SUV in the current and predicted vehicle fleet. Besides the safety aspects for SUVs and MPVs there is concern that SUVs and MPVs might have a poorer environmental performance than other cars. Results show that diesel engined SUVs and transporters had raised values for nitrogen oxides (NOx) and particulate matter (PM) emissions. MPVs did not show a worse environmental performance than the other vehicle segments. Gasoline SUVs and MPVs did not show any noticeable difference to other vehicle segments.
Proposed actions, regarding diesel engines and their NOx and PM emission, are that the type approval limits should be updated by the European Commission. To cover all SUVs not only the emission limits for vehicles of class M1 but also for N1 should be included. The ability to homologate SUVs as N1-vehicles should be scrutinised. If SUVs can be homologated as N1-vehicle, Europe can face the same problems as the US is dealing with regarding SUVs concerning emissions and safety.
With regard to fuel consumption ACEA has given the self commitment to reduce CO2 emissions of first car registrations (including SUVs and MPVs) to 140 g/km by 2008. An increasing number of vehicles with higher fuel consumption would make it more difficult to achieve the aim. It should be awaited to establish if this target will be reached. After that an updating of the ACEA reduction goal should be taken into account.
It is expected that taxes depending on emission standards or the amount of CO2 emissions would have a positive impact on the development of the emissions and fuel consumption of the vehicle fleet, so should be considered by the EC.
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3 Introduction
3.1 Background of the problem
Sales trends indicate that the European fleet is changing. Automobile manufacturers are offering a wider range of vehicle models in terms of kerb mass and body configurations. The growing number of Multi-Purpose Vehicles (MPVs) and Sport Utility Vehicles (SUVs) may create new safety issues for road safety in Europe. These vehicles, particularly SUVs, currently represent about 50% of new vehicle sales in the US and their growing market share has created a variety of safety issues in the US. Fatal car to car accidents involving SUVs are often caused by the enormous reduction of survival space of the occupant cell. This reduction of survival space is caused by incompatibility between the SUV and the passenger car. The source of the incompatibility is often the misalignment of crashworthy structures, mass differences between the SUV and the collision partner, as well as incompatible structural stiffness. Preliminary analysis of single vehicle collisions involving SUVs and roadside infrastructure indicates that SUVs are more likely to cause fatalities due to rollover, even when in contact with roadside safety equipment. These trends are obvious in the US accident research, however the extent of the problem in Europe is not yet known.
3.2 Objectives
The objective of the proposed study is to gain more insight and understand of the safety issues for SUVs in the European road network. Although there is a growing presence of SUVs in traffic, there is not any objective data to indicate the safety impact of SUVs in European traffic. Given the extent of the SUV safety problems observed in the US, it is critical that the SUV presence in Europe is monitored. Besides the safety issues for SUVs there is the general opinion that SUVs and MPVs exhibit a poorer environmental performance than normal cars. This holds both for fuel consumption and emissions of pollutants. The main reason for this is the increased vehicle weight and frontal area which raise the engine loads during city and highway driving. Therefore, the objectives of this study are: • Define the current size of the EU traffic injury problem in terms of partner and self-protection for SUV crashes. • Identify and define crash mechanisms occurring in collisions with SUVs. • Identify future expectations on traffic injury problem related to SUVs. • Determine fuel consumption and exhaust gas emission of SUVs and MPVs compared with the rest of the car fleet. To be able to reach these objectives, the project structured into four main research areas: • Definition of SUVs and MPVs
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• Data collection and analysis • Structural analysis • Environmental studies
3.2.1 Definition of SUVs The classification of cars according to their body shape is quite often used for categorising cars for crashworthiness or similar activities. Historically this classification has been introduced by car manufacturers. Some categories have been taken over by motor magazines, consumer organisations and also by accident researchers. However, a technically or legally based definition of the categories is often missing. The emerging discussion on Sports Utility Vehicles (SUVs), which initially started in the USA, demands a clear definition of this car category. This study presents an approach to categorise SUVs and MPV, into two separate and distinct groups.
3.2.2 Data collection
Sales figures The increase in numbers of SUVs appears to be due to the changing market in terms of what people wish to drive. Accordingly, it is reasonable to adopt a categorisation of vehicles based on existing broad market sections so that comments may be placed in the context of the fleet as it tends towards or away from any existing categories. The limited classification of vehicle body types makes a simple extraction of the sales figures for SUVs impossible. Two different approaches are provided, the first being an analysis of the European sales reported by ACEA and the second being a detailed review of individual model sales. The latter approach used models identified by the project group. Both approaches provide incomplete reporting of the sales figures, however can provide some general information on the relative size of the SUV market and trends in recent years.
National statistics National statistics from each participating country (UK, D, NL, S, F) were collected and analysed for the rates of involvement of SUVs during recent years and the injury outcomes associated with this. The categories required for comparison with SUVs were initially identified as: Mini; Light; Compact; Medium and Heavy family MPVs; SUVs.
In-depth accident cases The in-depth accident collection and analysis were carried out to further understand the problems and attempt to quantify the magnitude of the problems. In depth accident databases are required to perform this type of analysis, few of which exist for Europe. TRL and BASt carried out the analysis for United Kingdom and Germany, respectively. TRL used the On The Spot accident investigation (OTS) database and the Cooperative Crash Injury Study (CCIS) database. BASt used the German In Depth Accident Study (GIDAS) database.
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3.2.3 Structural analysis The objectives of this section are to review ongoing European research projects to identify the differences between SUVs and other road users in terms of mass, structure and stiffness as well as to review current test protocols for road equipment. Safety characteristics for SUVs are addressed in the following tasks associated with this work package:
Measurement of structural parameters Geometrical properties of the vehicle fleet have been previously investigated in the VC-Compat project. For compatibility good interaction between structural components is essential. A first indication of the interaction is obtained from geometrical data of the main members. In the VC-Compat project a database was created containing information about the best selling EU passenger cars. For the purpose of the current project this database was extended with top selling SUVs and MPVs. Structural parameters for SUVs and MPVs were compared with data for passenger cars to provide geometrical differences between passenger cars and SUVs.
Fleet studies Modifications of the injury and fatality rates may be expected when there are changes to the vehicle fleet composition. The influence of vehicle mass distribution on injury and fatality rates was investigated earlier by Buzeman et al. (1998). This analysis approach was reapplied to check if the change in the mass and vehicle type distribution due to the increasing number of SUVs can involve an increase of the fatality and injury risks, affecting to the road safety. A second fleet systems modelling approach, developed under the VC-Compat project, was applied to analyse the SUV compatibility problem. Numerical simulations of crashes between vehicles of different classes were performed to obtain information on injuries. Simulations were performed for different crash parameters (speed, angle, etc.). In addition the influence of the front-end stiffness values and profiles were investigated using generic vehicle models. Stiffness values were derived from available crash test data and the geometrical measurements.
Road restraint systems Road restraint system test requirements in EN-1317 were reviewed in terms of test vehicle specifications.
3.2.4 Environmental issues Besides the safety aspects for SUVs and MPVs there is concern about the issue that SUVs and MPVs might have a poorer environmental performance than other cars because they have an increased vehicle weight and frontal area which raise the engine load during acceleration and high speed driving. This might be the cause of both rising fuel consumption and increased emission of pollutants.
The aim of this study was to determine the fuel consumption (CO2-emissions) and the exhaust gas emissions of SUVs and MPVs in comparison with those of other cars. With regard to the exhaust gas emissions the focus was on the limited
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components HC (hydrocarbons), NOx (nitrogen oxides), CO (carbon monoxide) and PM (particulate matter in the case of cars with diesel engines).
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4 Method and Results In this chapter the research methodologies are explained per item and a summary of the results are given. The detailed data sets and results can be found in the annexes per WP. WP 1.1 Data collection WP 1.2 In-depth accident analysis WP 1.3 Structural analysis WP 1.4 Environmental issues
4.1 Definition of SUV
The classification of cars according to their body shape is quite often used for categorising cars in rating activities. One example is EURO-NCAP which provides crashworthiness information. Historically this classification has been introduced by car manufacturers. Some categories have been taken over by motor magazines, consumer organisations and also by accident researchers. However, a technically or legally based definition of the categories is often missing. The emerging discussion on Sports Utility Vehicles (SUVs), which initially started in the USA, demands a clear definition of this car category. This report presents an approach to be able to categorise SUVs and MPVs. It is intended that in the end MPVs and SUVs will be separate and distinct groups, hence a car is either a SUV or a MPV. The starting point for developing a definition is a review on the legal definition of “off- road” or “off-highway” vehicles in the USA and in Europe. SUVs are derived historically from off-road vehicles. Simultaneously, official definitions of the MPV- category are reviewed. An approach to describe SUVs and MPVs was based only on technical parameters as opposed to their body shape or size is a quite often used in consumer ratings. This concept could then be used to identify those car categories in national accident databases for research purposes. The classification of cars according to their body shape or size is a quite often used methodology for categorizing cars e.g. in crashworthiness ratings. This is done because cars of different segments are often not directly comparable. Parameters used for classification were vehicle mass, market category, engine size or wheelbase. Categorisation schemes introduced by car manufacturers that use categories like Minis, family cars, MPVs and SUVs became well known to the public by motor magazines and consumer organisations and are nowadays also often used by accident researchers. However, these terms do not have any technically or legally based definitions.
4.1.1 Unified SUV and MPV definition The state of the art study has shown that on the one hand neither the American nor the European definition of off-road vehicles can immediately be used for defining SUVs. On the other hand both definitions describe most SUVs quite correctly. By
10 IMPROVER Final Report: Subproject 1 TREN-04-ST-S07.37022 using the off-road definition with some minor changes it could be possible to construct a good and meaningful SUV definition. The intuitively expected outer appearance of a SUV is in line with the geometrical requirements (ground clearance, approach angle, etc.) in both US and European definitions. The problem is caused by non 4 wheel driven cars which do not reach a certain GVWR. Following this argumentation, the geometrical demands have been kept, while the additional requirements have been abandoned. As this project has the major intention to find suitable definitions for the European car fleet, the geometrical requirements from the regulation 70/156/EEC have been adopted. Most SUVs in Europe fit the group of M1-class-vehicles. Therefore, pickups and other N-class vehicles have been eliminated in this study due to their relatively small market share in Europe. This is a very different situation compared with the USA, where pickups compose a significant part of the car fleet. A database analysis of about 20,000 car make and models has been compiled to find more parameters which could be helpful in identifying SUVs and MPVs. It came out, that the height of a car is a good predictor. A height of 1600 mm proved to be useful for distinguishing SUVs and MPVs from salon, hatchback and convertible cars. The height limit of 1600 mm excludes cars which, are capable of off-road operations, however are generally not considered to be a SUV. Setting a mass limit to the SUV and MPV definition instead of setting a height limit proved to be less successful. The final definition for SUVs and MPVs is shown in Table 4.1. Following this definition MPVs and SUVs build up distinct groups of cars, MPVs being all cars (except SUVs) with a height of more than 1600 mm.
Table 4.1 Final definition of SUVs and MPVs Requirements SUV MPV Approach angle > 25 ° - Departure angle > 20 ° - Ramp angle > 20 ° - Front and rear axle > 180 mm - ground clearance Ground clearance > 200 mm - Geometrical requirements between axles Height > 1600 mm > 1600 mm AND AND Vehicle class (in M1-class- M1-class- accordance with reg. vehicle vehicle 70/156/EWG) On’s Add- - Not being an SUV
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4.2 Data collection
To identify the size of the safety problem with SUVs in Europe, the sales figures and the national statistics are collected for Europe.
4.2.1 Sales figures Using the total sales figures from Europe, it is possible to see a general trend of increased sales of SUVs in the last few years. Since no specific SUV or LTV category was available, the Four Wheel Drive (4WD) share of new passenger car registrations was used to approximate SUV sales. The share of 4WD vehicles of the last 15 years are shown in Figure 2.3 for the EU 15 countries. The average for the EU in 2003 was 6% with Belgium, Denmark, Finland, France, Ireland, the Netherlands, Portugal, and Spain having less 4WD sales than the EU average and Austria, Germany, Greece, Italy, Luxembourg, Sweden, and the UK having more than the EU average. It is important to note that the countries under the EU average represent about 21% of the EU15 4WD sales and the remaining countries represent 79% of the sales.
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Austria Belgium 10 Denmark Finland i France 8 Germany Greece Ireland 6 Italy Luxembourg Netherlands 4
% New Vehicle New % Registrat Portugal Spain Sweden 2 Uni ted Ki ngdom EU15 0 1988 1990 1992 1994 1996 1998 2000 2002 2004
Figure 2.3 Historical sales of FWD in the EU15 countries
In a detailed search of 47 vehicle models classified as SUVs, the share of new vehicles sales in 2003 was 4.6%. This value is somewhat lower than the 6% provided in Figure 2.3, but reflects SUV models identified by the project group. Figure 2.3 includes other 4WD vehicles that may not be SUV type vehicles such as AUDI and Subaru 4WD passenger cars.
4.2.2 National accident statistics For the selection of national statistics, mass groups were created based on the models tested by EuroNCAP. The boundaries are chosen so that the categories correspond approximately to models that have been placed in the Supermini, Small,
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Large and Executive family car. Clearly there will be some incorrect categorisation of some vehicles, however this is minimised by having the bands as few and wide as shown. Table 4.2 Mass groups of models Category On BASt’s And has mass And has mass And is a SUV list greater than or less than or passenger car equal to equal to SUV Yes No lower limit No upper limit Yes MPV Yes No lower limit No upper limit Yes Mini No No lower limit 1050kg Yes Light No 1051kg 1250kg Yes Medium No 1251kg 1450kg Yes Heavy No 1451kg No upper limit Yes Interpret mass to mean kerb weight. Note that the SUV category is exclusive from the other categories – so no SUVs occur in the other groups. It is recognised that the SUV category will itself be associated with a higher average mass than the whole fleet, and even if their possible higher risk for the opponent car occupant is explained to some degree by this factor it still remains that the scope of this work is to examine the importance of this group in the accident statistics. Accordingly, the following sections list the required minimum output from each national database.
Detailed requirements The UK data was taken from the years 1998-2002. Serious injury is judged to be any injury requiring hospitalisation, any injury involving a fracture, any internal injury, or any “serious” laceration. These decisions are made at the scene by a police officer. Fatal injuries are those resulting in death within 30 days of the accident date. The Swedish data was taken from the years 2003-2004. It does not distinguish between rollover and non-rollover accidents. Seriously injured is according to the police. The instructions to the police are as follows: A seriously injured person is a person who has a fracture, contusion, serious cut, concussion or internal injury. A serious injury is any injury which is expected to lead to admission to hospital. Fatal injuries are those resulting in death within 30 days of the accident date. The Swedish data is incapable of determining if a collision actually occurred, where data is given it is for the primary traffic elements. If there was a collision it was between these elements. The Dutch data is taken from the years 2001 – 2003. Any collision in the Dutch data is between the primary traffic elements, that is those two vehicles which initially collided, rather than any others involved in a multi-vehicle collision. The German data is taken from the years 1999-2003. It does not distinguish between rollover and non rollover accidents. To compare the severity of the outcome in two passenger cars that hit each other: In the following table, the number of accidents reported will be split just by the difference in outcome between the two cars – not the actual severity. That is, an accident in which there was a fatality in a light car that collided with an SUV
13 IMPROVER Final Report: Subproject 1 TREN-04-ST-S07.37022 containing a serious injury would be counted as equivalent to one in which there was a slight injury in a light car that collided with an SUV containing no injured people since the passengers in the light car show a higher injury in both cases.
Table 4.3 Severity comparison Severity Comparison: SUV MPV Mini Light MediumHeavy Unknown All UK SUV Lower 0 4 36 39 6 1 54 140 Equal 4 18 170 220 60 2 273 747 Higher 0 4 11 20 8 0 48 91 MPV Lower 4 0 64 63 8 0 68 207 Equal 18 36 466 568 119 19 505 1731 Higher 4 30 25 56 18 3 69 205 Sweden SUV Lower 0 1 3 6 10 11 31 Equal 0 018811 28 Higher 01116 9 MPV Lower 0 15 41 40 28 124 Equal 0 0 14 31 46 42 133 Higher 4 1 8 20 34 43 110 Holland SUV Lower 0 110412 2341 Equal 0 5 25 15 11 5 69 130 Higher 0 15025 1427 MPV Lower 1 3 45 12 7 7 20 95 Equal 5 24 122 80 36 44 42 353 Higher 1 3 15 12 7 12 6 56 Germany SUV Lower 0 129 59 703 1393 2769 5053 Equal 13 100 12 210 540 1520 2392 Higher 57 114 9 107 374 1307 1966
Summary of results SUV are at a greater risk of overturning in single vehicles collisions compared to other classes. The Dutch and UK data sets support this conclusion, though they record significantly different levels of rollover accidents. The German and Swedish data did not distinguish between rollover and non rollover accidents, and so did not contribute to this conclusion. The Dutch data suggests that SUV occupants are at lower risk of serious or fatal injury in single vehicle accidents without overturning. The UK data do not show the same effect, which may be down to national differences between the accident populations. All the national datasets show that SUV occupants appear to be at no greater or lower risk of suffering serious injury in all single vehicle accidents combined. SUVs tend to be causing higher injury levels than other vehicle classes in collisions with two wheeled motor vehicles, both motorcycles and mopeds. This conclusion is supported by the Dutch, German and Swedish data. The different datasets can not be used to identify the different levels of the effect. The UK data does not strongly support this conclusion.
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Dutch, German, and UK data suggest that SUVs offer no more severe injury outcomes to pedestrians than other classes of car. The Swedish data strongly disagrees, suggesting a much higher injury severity for pedestrians hit by SUVs. We believe a detailed look at SUV pedestrian interaction would be useful. Several factors such as impact speed and pedestrian age can have a large influence on injury outcome, and if it is found that SUVs tend to have more accidents at slow speeds with child pedestrians, it may emerge that the apparent average performance of SUVs in terms of protecting pedestrian impact partners may not reflect their true performance, when compared to other classes in similar collision conditions. Similarly an analysis of two wheeled motor vehicle collisions with SUVs would be desirable, intending to determine why SUVs seem to offer such severe collisions to these vehicles. An interaction between the roof rail of the SUV and the two wheeled motor vehicle rider’s head has been suggested, but more work could confirm or deny this. In the comparison of severity between SUV/MPVs and collision partners, the German data shows that SUVs suffer lower severity than collision partners. The German and UK data also shows that SUVs suffered lower severity when compared to any other class individually. The data from the other three partners strongly support this conclusion. The Dutch and Swedish data show similar conclusions, with less data points.
4.3 In-depth accident analysis
Two existing in-depth accident databases are used to perform the collection and analysis of in-depth accident cases to identify the differences between SUVs and passenger cars in various accident scenarios. TRL and BASt carried out the analysis for United Kingdom and Germany, respectively. TRL used the On The Spot accident investigation (OTS) database and the Co-operative Crash Injury Study (CCIS) database. The German analysis was based on the In-Depth Accident database GIDAS (German In-Depth Accident Study), which is driven by a consortium of BASt and FAT (German Association for Research on Automobile-Technique).
Scope of the German Data For the present study, evaluations were made of accidents from the last 6 years from 1999 to 2004. During this period, a total of 4,999 accidents with passenger car participation - 65 (1.3%) with SUV participation - were documented by the teams. 7,144 cars have been recorded in those accidents, 65 (0.9%) of them have been classified as SUV - type vehicles. Due to the small amount of available SUV accident cases no case selection criteria were applied to the data. Instead each of the 65 accidents with SUVs participation was looked at in detail.
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Table 4.4 Accident Type of SUVs and non SUV – type vehicles [GIDAS data set] Accident Type non SUV - type vehicle SUV - type vehicle Car to Car 34% 51% Car to Truck 6% 5% Car to Motorcycle 10% 6% Car to Cycle 18% 14% Car to Pedestrian 13% 5% Single Car Accidents 18% 18% Others 1% 2% Total 100% 100%
Table 4.4 shows the distribution of accident type of SUV and non SUV - type of vehicles. Both distributions are quite similar. There is a higher share of pedestrian accidents for non SUV – type cars. However this could be explained by the higher percentage of urban accidents (72 %) within the non SUV – type category, compared to a percentage of 60 % in the SUV – type vehicle category. Table 4.5 Rollover Accidents of SUVs and non SUV vehicles [GIDAS data set] ROLLOVER non SUV - type vehicle SUV - type vehicle no rollover 96% 85% rollover 4% 15% Total 100% 100%
As shown in the national accident statistics, SUV – type vehicles show a much greater share of accidents with rollovers. This can also be seen from Table 4.5. The risk of having a rollover with a SUV is therefore four times higher as compared to a non SUV – type of vehicle. For the UK data set, the selection method and results are presented in the Annex WP 1.2.
The analysis results are: • SUVs have a higher risk for turnover accidents. The risk is about four times higher compared to non SUV – type vehicles. • SUVs are often used for the transportation of goods and trailers. This can lead to unstable driving situations and thus increasing the risk of turnovers in the event of an accident. • SUVs can be especially dangerous in accidents with pedestrians. Due to the steep front structure of SUVs the risk for head injuries for a pedestrian is high. • SUVs are incompatible in accidents with other cars. The geometrical and stiffness differences between SUV and non SUV – type vehicles result in low or almost no structural interaction of the energy absorbing structures. • SUVs show better protection for their occupants in truck accidents. Higher front structures lead to a lower risk for underruns.
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4.4 Structural analysis
4.4.1 Measurement of structural parameters In the 5th framework project VC-COMPAT [VC-Compat 2003] a database was created with geometrical measurements of the main vehicle structures. From accident analysis and crash testing these structures were identified as the main structures involved in frontal and side impacts. Within the VC-COMPAT project, this database was used to study current car-to-car geometric mismatch with a focus on compatibility. The cars selected for this database represent each car category in Europe and the 55 cars represent approximate 60% of the European sales in the year 2003. In Table 4.6 the European sales numbers for each mass category of MPVs and SUVs are given. The SUVs are representative of 5% of the European sales volume in 2003 and MPV are representative of 13%. Table 4.6 European sales number for the each size of MPV and SUV 2002 2003 2002 2003 Sales % Sales % Sales % Sales % number total number total number total number total SUV fleet fleet MPV fleet fleet Small 140,861 0.85 145,750 0.90 Small 238,509 1.45 272,375 1.68 Midsize 509,727 3.09 620,032 3.82 Midsize 1,905,953 11.56 1,930,622 11.88 Large 2 0.00 1 0.00 Large 173 0.00 1,656 0.01 TOTAL 650,590 3.95 765,783 4.71 TOTAL 2,144,635 13.01 2,204,653 13.57
To complement the VC-Compat database which had a limited number of SUVs and MPVs, a number of new vehicles were selected for measurement to provide more complete information on the relationships between passenger cars and SUVs. This section describes the measurement methodology in four steps: • The selection of SUVs and MPVs for measurement • The measurements performed on the selected cars • Integration of the results into the existing database • Analysis of the structural database
Selection of cars In the VC-COMPAT project, 5 SUVs and 9 MPVs have been measured following the “3D_measurment protocol V2.3”, [VC-Compat]. Ten different SUVs and MPVs were selected for measurement to the VC-Compat protocol. The selection of these vehicles was based on the following criteria: • Best sales volume for MPV and SUV • Vehicles from different mass/size category : small / midsize / large • Sales volume >0.1% of the total fleet In the following table the selected cars are given, note that the cars displayed in italics were already measured within the VC-COMPAT project. Furthermore, the sales volume of large SUV and MPV was too low to include them in the current study.
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Table 4.7 Selected cars in the structural database (note: cars in Italic are already measured in VC-COMPAT). Nissan Almera Small Tino Small Toyota RAV4 MPV Opel Agila SUV Suzuki Jimny Renault Scenic Nissan Xtrail Citroën Picasso Land Rover Freelander Opel Zafira BMW X5 Renault Kangoo Mercedes M-Class Midsize Citroen Berlingo Midsize Hyundai Santa Fe MPV Opel Meriva SUV Mitsubishi Pajero Renault Espace Volkswagen Touareg VW Sharan Honda CRV Citroën C8 Volvo XC90 VW Touran Range Rover
The completed list with ten SUVs and ten MPVs measured represent (by sales volumes) 59% and 76%, respectively. The detailed information is given in Table 4.8.
Table 4.8 Sales representative for MPV and SUV. Selected cars - % for the vehicle class Year 2003 MPV SUV Small 64.4 82.8 Midsize 77.5 52.8 Large 0 0 TOTAL 75.8 58.6
Measurement and integration of the geometric parameters In total three MPVs and seven SUVs were measured. The geometric parameters measured are defined in the 3D measurement protocol of the VC-COMPAT project and over 60 points are recorded. The ten additional measured vehicle were added to the pre-existing list. The database containing the data points can be requested from UTAC for research projects.
Summary of results It is universally accepted that structural interaction, frontal force levels, and passenger compartment strength are important issues in vehicle crash compatibility. Structural interaction is seen as of primary importance because the main concern after the impact has begun is to ensure that the load paths work as intended in order to absorb energy. To achieve this, it is essential to distribute the initial impact load across the entire contact surface. To ensure that crash loads are efficiently supported in the vehicle, it is important to have several load paths and to create a front face spreading out the loads over a large surface. Car to car tests have demonstrated that structural parts playing a role for good structural interaction are the longitudinals and crossbeam, engine subframe and, for side impact, the floor sills.
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The following data presents the positions of these main structural parts for the SUV and MPV fleet, and can be compared to the mean position of the corresponding structures within the car fleet. Table 4.9 gives an overview of all the SUVs and MPVs measured, with their mass and Centre of Gravity (CoG).
Table 4.9 Measured MPVs and SUVs, including mass and Centre of Gravity (CoG) in the z- direction Position of CoG in the Z axis Mass (kg) (Height from the ground in mm) Small 1 Nissan Almera Tino 1477 628 MPV 2 Opel Agila 1243 655 Midsize 3 Renault Scenic 1592 593 MPV 4 Citroën Picasso 1578 602 5 Opel Zafira 1687 624 6 Renault Kangoo 1288 640 7 Citroen Berlingo 1508 655 8 Opel Meriva 1587 621 9 Renault Espace 2263 691 10 VW Sharan 1948 689 11 Citroën C8 1923 711 12 VW Touran 1768 650 Small 13 Toyota RAV4 1682 655 SUV 14 Suzuki Jimny 1341 686 Midsize 15 Nissan Xtrail 1761 666 SUV 16 Land Rover Freelander 1827 647 17 BMW X5 2381 737 18 Mercedes M-Class 2444 708 19 Hyundai Santa Fe 2003 666 20 Mitsubishi Pajero 2312 717 21 VW Touareg 2603 705 22 Honda CRV 1678 672 23 Volvo XC90 2058 - 24 Range Rover 2329 753
The average mass and position of CoG from ground is given in Table 4.10. The mass ratio between SUV and passenger cars is 1.4, where that for the MPVs is 1.2. Furthermore, the trend is similar for the position of the Centre of Gravity. The SUV‘s CoG is the highest and it is positioned 100 mm higher than for passenger cars while MPVs are in between the SUV and passenger car values. Table 4.10 Average mass and CoG for the passenger cars, SUVs and MPVs Car fleet MPV fleet SUV fleet Mass (kg) 1376 kg 1592 kg 1968 kg Position CoG (heigt from ground in mm) 574 mm 631 mm 683 mm
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The position of the cross beam member is given in Figure 4.1 where the dashed line gives the average cross beam measurements of the passenger cars.
• Position of crossbeam
Mean position for Crossbeam the car fleet Position from the ground MPV SUV 700
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Height from ground (mm) 350
300 123456789101112131415161718192021222324 Vehicle n° top bottom Figure 4.1 Position of crossbeam, bars and the dashed lines the average passenger car crossbeam
Table 4.11 Mean crossbeam position, weighted mean height from ground and the weighted delta (height of the beam itself). Crossbeam Car fleet MPV fleet SUV fleet Weighted mean height (mm) 463 463 503 Weighted delta (mm) 97 96 100
The position of the bumper is aligned with the legal bumper requirements and this does not imply that the bumper is aligned with crossbeams and lower rails. Bumper measurements are a subjective measure and interesting only for low speed impacts, pedestrian safety, and other vulnerable road users. In high speed impacts the combination of lower rail and crossbeam are the important structures which interact with the opponent vehicle. In most cases the crossbeam and lowers rails are aligned in height, therefore those measurements should be analysed together. There are examples where there is a large misalignment that could introduce a bending moment during the crush. This bending moment will lead to an incompatible crash interaction.
4.4.2 Fleet safety analysis based on global vehicle properties A statistical model of the European fleet was used to predict the influence of changes in the sales of SUVs. This approach assumes that the risk for an accident for a
20 IMPROVER Final Report: Subproject 1 TREN-04-ST-S07.37022 particular vehicle is independent of the mass of the vehicle. Therefore the probability curve for accidents is the same that of the mass distribution of the fleet. Buzeman et al. (1998) used the probability of accidents for each impact speed presented by Evans (1994). This approach was calibrated to Swedish statistics and provided a reasonable accuracy for a baseline calculation. The results presented herein are based on the German crash data collected by BASt and represents a significant portion of the frontal accidents for Europe. Note that this analysis is only applicable to frontal impacts. The model builds on the idealized conservation of linear momentum approximation for frontal crashes. In this approach, the velocity changes of the vehicles are expressed by the ratios of their mass and their relative closing velocity prior to impact: M ∆V = V 2 1 imp M + M 1 2 (1) M 1 ∆V2 = Vimp M 1 + M 2
The velocity change of the vehicle during a crash is often used to predict injury. Based on previous research, the risk for serious and fatal injuries can be extracted from accident data and are shown in Figure 4.2. To investigate the effect of the incompatible geometry between SUVs and passenger cars the same injury and fatality risk curves can be used. When the crash is between two different vehicles types (SUV and passenger car), the risk curves for passengers of the small cars are multiplied by 1.4 and 4.5. Summers (1999) shows that the driver’s fatality ratio for a frontal collision SUV-to-car is 1:4.5, while the injury ratio given by Austin (2005) for the driver is 1:1.4. This means that when a SUV and a passenger car collide in a head on collision, the car driver’s fatality risk is 4.5 times that for the SUV driver.. The corresponding risk for serious injuries to the car driver is 1.4 times than that for the SUV driver.
1,2
1 1,2
0,8 1
SUV 0,8
0,6IR SUV Car Car 0,6FR 0,4 0,4 0,2 0,2
0 0 0 102030405060708090100 0 102030405060708090100 ∆∆VV [km/h][km/h]Change of Speed (Km/h) Change of speed (Km/h) a) b) Figure 4.2: : Risk curves for occupant injuries a)-serious injuries & b) fatal injuries
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The risk curves derived for passenger car-passenger car and passenger car-SUV impacts are based on US crash data in recent decades. In order to assess the relevance of US vehicles to European vehicles, the centre of gravity position for the EU fleet (as presented in the previous section) and the US fleet representative for the collected crash data is presented in Figure 4.3. The reference fleet (US) has a higher variation than the European fleet and a maximum CG height 85 mm higher than the highest measured value in the IMPROVER database. This would indicate that geometrical (structural) interaction between SUVs and passenger cars in the US would be less effective than in Europe. Therefore the risk curves developed for the US fleet would only represent extreme (worst) cases in European traffic.
900
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CG Height [mm] Height CG 300
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0 EU USA
Figure 4.3 Comparison of SUVs Measured in the with Reference US SUV Fleet
To have an idea of the relevance of SUV crash behaviour on road safety, the influence of the SUV geometry must be assessed independently of the vehicle mass. To achieve this analysis was performed to investigate the change in the European vehicle fleet mass due to SUV sales in Europe. The analysis established a baseline for injury risk based on a surrogate for the current vehicle fleet. This surrogate was sales data recorded in 2003. Then, a fleet based on predicted sales figures for 2008 was constructed. The fatality and injury risk for the 2008 fleet was calculated for the following assumptions: 1. SUVs can be considered as a heavy passenger car 2. SUVs are geometrically different and create more severe loading on the impact partner The 2008 fleet had twice the SUVs as the 2003 fleet (approximpately 9% compared to 4.5%).
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The first piece of analysis explores the case where only mass effects occur due to a shift from passenger cars to more SUVs in the vehicle fleet. In the second piece of analysis, US compatibility research was used to modify the injury risk curves for collision partners with SUVs. Since the vehicle fleet in the US is likely more aggressive than the European fleet (due to a higher deviation between SUV and passenger car geometries), two risk approaches were investigated. The worst case for Europe was predicted based on the US levels of SUV incompatibility and an intermediate level where the European SUV fleet is only "half as incompatible" as the US SUV fleet.
The simulation results are presented in Table 4.12. The baseline column indicates what the model predicts for the present fleet conditions. For reference, the 2003 serious injury and fatality rates are 92.7/100,000 and 8.5/100,000 accidents for Germany (the source of the impact speed distribution). The model slightly under- predicts the number of serious injuries and over estimates the number of fatalities. However the model is in the right order of magnitude for these estimates and should be a reasonable tool for evaluating the influence of SUVs on fleet safety. It should be noted that the analysis is using the sales data to represent the vehicle fleet and not the actual running stock.
Table 4.12: Fleet Model Results Predicted Baseline Mass Mass + Mass + Geometry (a) Geometry (b) 2003 2008 2008 2008 The Average Injury Rate per crash is: 0.5334 0.5263 0.532 0.5371 The Average Fatality Rate per crash is: 0.3402 0.3213 0.3362 0.3503 The predicted Severe Injuried per 100000 11.5101 11.3566 11.481 11.5879 registered vehicles are: The predicted Fatalities per 100000 7.3418 6.9332 7.2557 7.5604 registered vehicles are: (a) - Intermediate Case (b) Worst Case
It can be observed that the changes in the injury values are quite small. This can be accounted for by the small representation of SUVs in the fleet (about 9%) for the 2008 predictions. Even when the incompatibility effects are included, a very small increase is observed. It is important to observe the geometry effects are greater than the mass effects. Only using the mass effects for the SUVs resulted in a small decrease in casualties. If the SUV incompatibility in Europe is only half as bad as the US, then any safety benefits gained by the mass distribution of the fleet is removed by the geometrical properties of a small portion of the total fleet. If all the problems observed in the US are introduced in Europe, the geometry effects counteract any benefits from the mass distribution and then add a further increase in the casualty rates. This underlines the necessity to ensure that SUV geometry must not become more incompatible than currently observed in the US [Summers]. To clarify the decrease in casualties when the mass of the fleet increases, one can refer to Buzeman et al. (1998). They investigated a uniform increase in the mass of the fleet and it was observed that there were slight decreases in both the fatalities
23 IMPROVER Final Report: Subproject 1 TREN-04-ST-S07.37022 and the injuries. In this study, increasing the average mass by 10 kg, resulted in 0.5% less injured and 1.7% less fatalities from the baseline. The decrease of the risks when raising the mass can be explained as a result of taking away part of the lighter vehicles as well as slightly reducing the average mass ratio which reduces the expected velocity changes (see equation (1) for the fleet). Buzeman et al. (1998) demonstrated that to take away the lightest vehicles caused a decreased risk for injuries in the fleet.
Summary of results With the results obtained from the simulations, it can be deduced that SUVs will produce a very small change in the fleet’s mass distribution. The influence of mass, separate from other structural parameters for the vehicles, can produce minor changes in the road safety levels for Europe. However geometrical differences between SUVs and passenger cars appear to have a more noticeable, negative, effect on road safety in Europe. The analysis highlights that the incompatibility of SUVs in frontal impacts with passenger cars is more important to monitor than the mass. This is fortunate as it is easier to implement geometrical requirements for motor vehicles than regulating the mass. This approach has already been applied to the US market through the Alliance of Automobile manufacturers [www.autoalliance.org].
4.4.3 Geometrical approach fleet systems analysis A vehicle systems model developed at TNO Automotive was applied to analyse the SUV compatibility problem. Numerical simulations of collisions between vehicles of different classes were performed to obtain information on: • The factors leading to unbalanced structural interaction, • The crash mechanisms involved with these structures, • And the injury mechanics that occur in typical SUV involved accidents, Simulations were performed for different crash parameters (speed, angle, etc.). In addition, the influence of the front-end stiffness values and profiles were investigated using generic vehicle models. Stiffness values were derived from available crash test data and the geometrical measurements. Detailed insight into the compatibility issues of SUVs is needed to identify the differences between SUVs and other road users in terms of mass, structure and stiffness and its implication on road side infrastructural requirements, current test protocol applicability and fleet compatibility in general. A vehicle systems model developed at TNO Automotive was applied to analyse the SUV compatibility problem.
Scenario Set-up A short-term initial step in addressing further improvements in front-to-front crash compatibility between two colliding vehicles is through better alignment and geometric matching of the vehicle crash structures. There were three different options: 1. Geometric matching of the Primary Energy Absorbing Structure (PEAS),
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2. Enhancement of the Primary Energy Absorbing Structure by supplemental of a Secondary Energy Absorbing Structure fixed to it (EPEAS), 3. Addition of a Secondary Energy Absorbing Structure (SEAS).
Table 4.13 Three options for improvement of SUV compatibility; vertical alignment (left), enhanced load path (mid) and additional load path (right).
PEAS EPEAS SEAS
The focus of this study will be on the first two options: Geometric matching of the Primary Energy Absorbing Structure (PEAS) and an enhancement of the Primary Energy Absorbing Structure (EPEAS). The first option can have an influence on the design process of future SUVs. The latter option can be applied to both future SUV development and modification of existing SUVs on the road. It was proposed for the scenario definition to have at least two car-to-car scenarios covered that represent respectively the US NCAP full overlap condition and the Euro NCAP 40% overlap condition, see Table 4.14. The US NCAP frontal crash is conducted with complete overlap against a rigid barrier at a crash speed of 56 km/h. The Euro NCAP frontal crash is conducted with 40% overlap at the higher crash speed of 64 km/h, in accordance with the EC Directive 96/79/EC. Whereas in the IMPROVER project the compatibility issue is evaluated, the barriers used in the NCAP tests are replaced by the bullet vehicle from the LTV vehicle class, being the SUV. The target vehicles were represented by the compact vehicle class, which has potential danger of under run in crashes that involve SUVs. Other scenarios following from the statistical accident information and the in-depth studies can be added to the scenario definition. Table 4.14 Frontal impact test conditions Legislation FMVSS 208 Euro NCAP Impact Angle Frontal (0°) Frontal (0°) Velocity 56 km/h 64 km/h Overlap 100% 40% Bullet vehicle SUV SUV Target Compact Passenger Compact Passenger vehicles Car car Dummies 2 Hybrid IIIs 2 Hybrid IIIs Head, Neck, Chest, Head, Neck, Chest, Criteria Abdomen, Pelvis, Abdomen, Pelvis, Lower Extremities Lower Extremities
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Reference fleet The SUV was updated with respect to the generic ride height and stiffness characteristics. Then a simulation study was done in order to determine the influence of speed and overlap variation in both protocols of the fleet collided with the (current) average SUV.
Fleet with Enhanced SUVs The SUV model was adaptated with sub-frame and shear connection points. These enhanced vehicle models were simulated again under the same conditions as the reference fleet. It was proposed to vary each variable in the following way: • Enhancement of the PEAS by addition of extra structure linked to the PEAS of varying levels of stiffness, e.g. [very high – high – average – low – very low]. The SUV model had to be updated in order to: • Geometrically match the SUV to the target vehicle. • Add an energy absorbing element to the PEAS of the current SUV The performance improvement can also be assessed from the overall injury risk prediction that is often used. This injury prediction is a modified form of the Injury Severity Score (ISS). In this approach, injury risk functions are used to convert injury values into AIS levels, which subsequently may be transformed into an overall injury risk using, for example the Injury Severity Scale. Predictions of the Femur forces, most severe of HIC36 and Nij, and the most severe of the Chest Deflection, Chest 3ms and the Combined Thoracic Injury (CTI) criterion computed from the dummy models were compared against their injury risk curves to obtain the Abbreviated Injury Scores (AIS). Results for the target and bullet driver are presented in respectively Figure 4.4 and Figure 4.5.
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Figure 4.4 Computed values of the ISS and AIS of HIC36, NIJ, Chest 3ms, CTI, Chest deflection and FFC for the target driver at 100% overlap (left) and 40% overlap (right).
Figure 4.5 Computed values of the ISS and AIS of HIC36, NIJ, Chest 3ms, CTI, Chest deflection and FFC for the bullet driver at 100% overlap (left) and 40% overlap (right).
Summary of results The mere addition of a secondary structure (EPEAS) below the bumper of an SUV will not result in more safe situations for the passenger car. In the contrary, it results in an even worse situation. However, by balancing the secondary structure with respect to the primary structure, the EPEAS can be made effective.
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It was shown that the Enhanced Primary Energy Absorbing Structure (EPEAS) was effectively included in the SUV model. A medium longitudinal stiffness, medium-to- high EPEAS bending stiffness w.r.t itself and high EPEAS bending stiffness w.r.t the structure, was determined to be the best setup for the design parameters of the EPEAS. The set up showed that by the inclusion and balancing of the EPEAS: • The tendency of the SUV vehicle to overrun passenger cars was effectively removed, • The crash interaction between bullet and target vehicle in both 100% and 40% overlap situations was highly improved, • The passenger compartment remains intact in the impacts, • Overall injuries to the target driver were reduced in all cases, • Overall injuries to the bullet driver were reduced in the case of full overlap, but were slightly increased, although far within limits, in the case of 40% overlap. It was shown that the EPEAS is effective in reducing injuries in the passenger. It is therefore recommended to investigate the technical implementation of such systems in both current and modern SUVs. Research is necessary to explore the feasibility and level of ease of implementation. With regards to this, it is strongly recommended to develop a methodology that addresses the EPEAS technology implementation.
4.4.4 SUVs and the Standards EN1317 and EN12767 The EU legislation EN1317-1 (Road restraint systems – Part 1: Terminology and general criteria for test methods) and 12767 (Passive safety of support structures for road equipment – Requirements and test methods) define test vehicle characteristics for the Europe-wide performance standard for road safety hardware like guardrails, crash cushions, and deformable lighting poles. The impact tests are designed to simulate a crash of a passenger car or heavy vehicle into different structures. Although the standard only provides a performance baseline for the comparison of different safety equipment, it attempts to represent reasonable real world collisions though the impact speed, impact angle, and test vehicle specifications. To ensure a suitable (conservative) assessment of the safety performance, more severe crash conditions are specified in the standard than are encountered in the real world data. Standard EN1317-1 identifies several test vehicles (Table 4.15) and it is the three passenger cars (masses 825, 1300, and 1500 kg) that are relevant in this analysis. The test vehicle in EN12767 is identical to the 825 kg vehicle in EN 1317-1. The EN1317 European standard on road equipment establishes certain vehicle specifications for the impact tests.
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Table 4.15 Vehicle specifications at EN1317
Evaluation Criteria There are three essential types of test evaluation applied in these standards: • Post-crash Vehicle Motions • Occupant Injury Risk • Structural Performance These criteria are further specified in the standards. In terms of Occupant Injury Risk, the lightest test vehicle is the most relevant vehicle type since it will experience the most violent crash dynamics and thereby produce more severe occupant loadings. Further discussion of the light vehicle is not required in the following analysis. The structural performance and vehicle redirection/post-crash dynamics are influenced by the geometry and mass of the vehicle. The heavier vehicles will produce larger crash loads on the roadside structure and the higher centre of gravity
29 IMPROVER Final Report: Subproject 1 TREN-04-ST-S07.37022 vehicles will introduce rollover moments when roadside structures have contact areas below the vehicles centre of gravity. It is these issues that SUV vehicles will introduce to the European fleet. An analysis of single vehicle crashes in the US [NCHRP] indicated for the Light Truck and Van (LTV) and SUV vehicles that these heavier and higher vehicles are over represented in fatal rollover crashes. Since rollover should not occur in these types of legislated crash tests, it is important to consider the relevance of the problem. Particular findings show that SUVs were more likely to rollover than light trucks and that the heavier mass and higher stiffness of SUVs tended to produce more deformation in hardware items and caused the vehicles to come into contact with objects placed behind the protective device. Relevance of Test Vehicle Characteristics The definition of the SUV/MPV specified the overall height along with some tire- bumper geometry. Using the overall height and mass distribution of SUVs the representation of the EN1317 test vehicles to new car sales is presented in Table 4.16. It is evident that the passenger car classification specified in EN1317 represents about 50% of new vehicle sales and less than 2% of new SUV sales. One must recognize that there are heavy truck test vehicles for certain safety devices in EN1317. However, safety equipment can be designed and tested only for passenger vehicles. A further analysis of older SUV characteristics was conducted by Chalmers. As an additional criterion, one can use the centre of gravity (CoG) location of the vehicle to discriminate between SUV/MPV and passenger cars. In this analysis vehicles with CoGs above 0.58 m could be considered as SUVs. Test vehicle specifications in EN1317 (Table 4.15) list the highest height for the centre of gravity 0.53 m, thereby excluding any SUV. Table 4.16: Percentage of vehicles in baseline that are represented by EN1317 Mass SUVs Passenger cars 900 kg 0% 3% 1300 kg 0.3% 19% 1500 kg 0.9% 28% TOTAL 1.2% 50%
As a prediction of the possible vehicle fleet based on 2008 sales expectations, Table 4.17 shows the representation of test vehicles. Table 4.17: Percentage of vehicles in expected fleet (2008 sales expectations) represented by EN1317 Mass SUVs Passenger cars 900 kg 0% 3% 1300 kg 0.6% 18% 1500 kg 1.1% 27% TOTAL 1.7% 48%
Summary of results The current test vehicles employed to test roadside safety equipment is shown to poorly represent the SUV in the current and predicted vehicle fleet. Even without
30 IMPROVER Final Report: Subproject 1 TREN-04-ST-S07.37022 changes in the current sales and registration levels of SUVs (relative to passenger cars), SUVs are not represented by their mass or geometric properties in the current test standards. US studies have indicated a higher risk of rollover or undesired deformation of the safety device when SUVs collided with roadside structures.
4.5 Environmental issues
Inquiries showed that there is no literature about the environmental performance of SUVs and MPVs available. Besides this car manufacturers also do not have comprehensive data about this issue. For these reasons statistical data of the type approval authority of Germany are the basis for the calculations and estimations carried out within this study. All vehicles of category M1 have to fulfil the limits of the type approval procedure given in the directive 70/220/EEC. Therefore, type approval data for exhaust gas emissions have the advantage of being valid all about Europe and they allow comparison between different vehicle segments since the driving cycle behind it (NEDC = New European Driving Cycle) is the same for all vehicles. Within the calculation the following definitions will be used to distinguish between different vehicle subcategories: • The total car fleet is divided into segments. • A segment is divided into car types like “Golf”, “Astra” etc. • A car type is divided into models like “Golf 4”, “Golf 5” etc., diesel or gasoline engine. • Each model consists of vehicle types like “Golf, 1.8 l”, “Golf, 2.0 l”, “Golf Variant”, “Golf 4Motion” etc. In Germany the type approval authority provides lists with stock figures for all vehicle types. Besides this for each vehicle type lists of type approval values for emissions of pollutants and for CO2 (fuel consumption) are available. However, the different lists are not linked. Within the scope of the present study the German type approval authority linked the data for pollutants and CO2 with the data for stock for each vehicle type to produce a combined dataset which could be used for further evaluation. This was done for all selected car types. The selection started with a list of first registration numbers for all car types referring to the key date December 31st, 2004. This list is split up into the following ten segments: • Minis • Small vehicles • Lower medium class • Medium class • Upper medium class • Premium class • SUV • Convertible and roadster
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• MPV • Transporter (small goods vehicles) The groups of interest, SUVs and MPVs, are already separated. Out of this list the most important and accordingly best selling car types per segment were selected. The selection criteria was a registration share of more than 3 % within the segment. The choices of SUVs and MPVs for environmental issues correspond to a large extend to the list and definition of SUVs and MPVs established for the safety issues implicating that the ranking of best selling SUVs and MPVs in Germany complies to the European ranking for 2004. The above mentioned dataset for emission and stock of each selected vehicle type of the ten segments then was used to calculate the mean emissions per segment in g/km. The averages were weighted with stock since a distribution of the average mileage of the segments was not available. Since the stock list and the emission lists of the German type approval authority unfortunately refer to different dates a small amount of vehicles is not included in the intersection of the linked lists. To further reduce the amount of data and to eliminate vehicles which will leave the car fleet soon only the current models and previous models were taken into account.
Summary of results The environmental performance of SUVs and MPVs was assessed by comparing type approval data of best selling vehicles in Germany for CO2, CO, HC, NOx and PM. For limited emissions the results show raised values only for diesel engined of the SUVs and transporters (the latter being rather light goods vehicles than cars) for NOx and PM. Diesel SUVs showed nearly twice as many emissions as premium class vehicles, where emissions are NOx and PM. MPVs did not show a poorer environmental performance than the other vehicle segments in respect to emissions. In fact MPVs have the benefit to be able to carry more passengers than other car types. Gasoline SUVs and MPVs did not show any noticeable difference to other vehicle segments.
With regard to CO2 emissions and accordingly fuel consumption SUV and premium class cars show increased values. This result is not astonishing since these vehicle segments show higher vehicle masses, engine power and displacement. However, SUVs (like transporters) also have a higher pay load so that - depending on the use like for agriculture, forestry or similar purposes - higher fuel consumption can be justified if they are used as all-terrain vehicles. Tables with the stock weighted type approval data can be found in the annex WP 1.4. Based on the results of the evaluation of type approval and stock data given above it is difficult to derive unassailable recommendations. Nevertheless the following topics might be helpful for further actions with regard to the environmental performance of SUVs, MPVs or other special vehicle categories.
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For gasoline SUVs and MPVs no actions can be recommended with regard to the limited emissions since their emissions do not exceed those of other vehicle segments.
With regard to fuel consumption ACEA has given the self commitment to reduce CO2 emissions of first car registrations (including SUVs and MPVs) to 140 g/km by 2008. An increasing number of vehicles with higher fuel consumption would make it more difficult to achieve the aim. It should be seen if this target will be reached. After that an updating of the ACEA reduction goal should be taken into account. Feasible technical measures to reduce CO2 should be encouraged. See webpage: www.acea.be.
With regard to diesel engines and their NOx and PM emission the reduction of the type approval limits should be updated by the European Commission. To cover all SUVs not only the limits for vehicles of class M1 but also for N1 should be included. The permissibility of homologating SUVs as N1-vehicles should be scrutinised.
It is expected that taxes proportional to emission standards or CO2 would have a positive impact on the development of the emissions and fuel consumption of the vehicle fleet. For MPVs no measures should be undertaken since they do not show elevated emissions compared with other vehicle segments. All measures aiming at a renewal of the vehicle fleet can be recommended if older high emitting vehicles are eliminated from this group.
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5 Outcomes of the project
5.1 Safety
5.1.1 SUV and MPV definition Based on the off-road definition, a suitable definition for SUV was found. This definition is based on geometrical requirements and that the vehicle is a M1-class vehicle. The definition of a MPV was found based on one geometrical requirement, height > 1600 mm and is a M1 class vehicle and is not an SUV. In addition, a database analysis of about 20,000 car makes and models has been compiled. It came out that the height of a car is a good predictor. A height of 1600 mm proved to be useful for distinguishing SUVs and MPVs from salon, hatchback, convertibles and cabrio cars. The height limit of 1600 mm excludes cars which are capable of off-road operations, but are generally not considered to be a SUV. Based on the above mentioned definitions, a list of SUVs and MPVs was created to be used for selecting the accidents in the national statistics. The characteristic feature 'height' affects the frontal area and is hence responsible for higher drag resistance thus resulting in increased fuel consumption and CO2- emissions especially at higher speeds. However, with respect to environmental issues not only the drag resistance (height, frontal area) but also other criteria like e.g. weight, layout of powertrain (engine power and displacement, gear box design, etc.) will influence fuel consumption and CO2-emissions.
5.1.2 Sales numbers Using the total sales figures from Europe, it is possible to see a general increase of SUVs in the last few years. Since no specific SUV or LTV category is available, the Four Wheel Drive (4WD) share of new passenger car registrations is used to approximate SUV sales. The average for the EU in 2003 was 6% with Belgium, Denmark, Finland, France, Ireland, the Netherlands, Portugal, and Spain having less 4WD sales than the EU average and Austria, Germany, Greece, Italy, Luxembourg, Sweden, and the UK having more than the EU average. It is important to note that the countries under the EU average represent about 21% of the EU15 4WD sales and the remaining countries represent 79% of the sales. In a detailed search of 47 vehicle models classified as SUVs, the share of new vehicles sales in 2003 was 4.6%. This value is somewhat lower than the 6%. The Dutch sales figures are analysed in detail based on the list of SUVs and MPVs. The percentage of SUV sales has been increasing since 1998, however in the last two years there has been a stable number of SUV sales, 3.5 and 3.6%. The MPV sales have had the same trend in the last two years, 17.0% for both years.
5.1.3 Safety issues reported world wide Several research has been performed in recent decades concerning LTV (including SUVs and MPVs) safety issues, mainly in the USA. This research includes rollover,
34 IMPROVER Final Report: Subproject 1 TREN-04-ST-S07.37022 pedestrian, self-protection and partner protection to other road users. Most recent is the commitment of the US car industry stated in the Alliance proposal that all LTVs will have an energy absorbing structure in the interaction zone, zone 581 of the bumper requirement, to solve the large incompatible situation between LTV and passenger cars.
5.1.4 National statistics SUV are at a greater risk of overturning in single vehicles collisions compared to other classes. The Dutch and UK data sets support this conclusion, though they record significantly different levels of rollover accidents. The German and Swedish data did not distinguish between rollover and non rollover accidents, and so did not contribute to this conclusion. The Dutch data suggest that SUV occupants are at lower risk of serious or fatal injury in single vehicle accidents without overturning. The UK data do not show the same effect, which may be down to national differences between the accident populations. All the national datasets show that SUV occupants appear to be at no greater or lesser risk of suffering serious injury in all single vehicle accidents combined. SUVs tend to cause higher injury levels for the opponent occupant than other vehicle classes in collisions with two wheeled motor vehicles, both motorcycles and mopeds. This conclusion is supported by the Dutch, German and Swedish data, though again, the different datasets suggest different levels of effect. The UK data does not support this conclusion. Dutch, German, and UK data suggest that SUVs offer no more severe injury outcomes to pedestrians than other classes of cars. The Swedish data strongly disagrees, suggesting a much higher injury severity for pedestrians hit by SUVs. A detailed look at SUV pedestrian interaction would be useful. Several factors such as impact speed and pedestrian age can have a large influence on injury outcome. If it is found that SUVs tend to have more accidents at slow speeds with child pedestrians then it may emerge that the apparent average performance of SUVs in terms of protecting pedestrian impact partners may not reflect their true performance, when compared to other classes in similar collision conditions. Similarly an analysis of two wheeled motor vehicle collisions with SUVs would be desirable, intending to determine why SUVs seem to offer such severe collisions to these vehicles. An interaction between the roof rail of the SUV and the two wheeled motor vehicle rider’s head has been suggested, but more work could confirm or deny this. In the comparison of severity between SUV/MPVs and collision partners, the German data shows that SUVs suffer lower severity than collision partners. The German and UK data also shows that SUVs suffered lower severity when compared to any other class individually. The data from the other three partners strongly support this conclusion. The Dutch and Swedish data show similar conclusions, with less data points.
5.1.5 In-depth analysis To properly observe the effects of mass incompatibility on crash injury outcome, a further study would be required. It seems likely, however, that reducing weight
35 IMPROVER Final Report: Subproject 1 TREN-04-ST-S07.37022 inequality in the fleet is desirable, though it is acknowledged that this may not be practical. Both geometrical incompatibility and stiffness/mass incompatibility appear to be a factor in the accidents observed here. It is interesting to note geometrical incompatibility also appeared in at least one car to car accident. Nevertheless, the high structure of SUVs does not generally interact well with the cars seen in this study, and addressing this would have positive effect. Stiffness incompatibility is damaging to accident outcome in several of the accidents with SUV involvement. It is suggested that ensuring SUV stiffness in the energy absorbing structure is significantly less than the stiffness of the passenger cell in ordinary cars would start to address the more serious stiffness incompatibility cases. However, care must be taken to take increased acceleration based injury into account, and not to compromise the safety of the SUV occupants. There is a marked propensity for SUVs to roll over more easily than other vehicles. Rollover crashes can in certain circumstances result in more severe injury outcomes than other crashes, and this tendency to roll over will therefore have negative implications on occupant safety. Introduction of a legislative roll over test is recommended. In Germany it appears modern-type-SUVs are more often driven in residential areas. Bearing in mind their poor interaction with pedestrians and other road users it is recommended to observe this trend very carefully. Finally, as the composition of the vehicle fleet changes it is thought to be important to repeat studies of this kind, to observe the effects of the increasing number of SUVs in the fleet. It takes some time for newer models to be seen in in-depth databases. Further studies of this nature would help confirm trends in this analysis which are not certain due to the small numbers of SUVs appearing in the databases at this time.
5.1.6 Structural analysis The physical parameters for the SUV and MPV vehicles sold in Europe were studied in different ways. A structural survey was used to determine the geometric characteristics of vehicles, a risk based safety model was used to identify the changes in fatality and injury data, and numerical modelling was used to identify design alternatives for the SUVs. All three approaches indicates that there are safety risks associated with SUVs but it was not clear how much MPVs affect the global safety picture. The structural survey indicates that there SUVs are less likely to interact well with passenger cars than an MPV. The SUVs had a large variation in the position of the main crash structures and this leads to a greater risk of poor structural interaction. From the misalignment of SUV and passenger car structures a risk analysis of the increased sales of SUV was investigated. Using the observed injury risk relationships measured in the US, a statistical model for frontal crashes was used to observe the changes of traffic casualties based on the mass influence of SUVs and the combined effects of mass and structural interaction. The study showed that the influence of structural interaction properties is stronger than the influence of mass. A small increase in fatalities and severe injuries is predicted if the future vehicle fleet has a larger share (8%) of SUVs than the current values (4%).
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Further investigation of the structural interaction of SUVs and passenger cars was conducted using different design options. This analysis indicated that a simple geometric interaction was not sufficient for reducing road casualties. The incorporation of a suitable, compatible SUV front requires both a stiffness matching as well as geometric matching of vehicle fronts. The combined results from these three analyses indicates that the current type of SUV is not compatible with European passenger cars. Increased sales of the SUVs identified in this study will result in increased injuries in the European road network. Although it is not easy to predict, the 2002 sales levels (4%) can be expected to double by 2008 reaching about 8%. If current SUV designs do not change, we can expect a small but observable increase in injuries associated with accidents involving SUVs. The analysis highlights that the incompatibility of SUVs in frontal impacts with passenger cars is more important to monitor than the mass. This is fortunate as it is easier to implement geometrical requirements for motor vehicles than to regulate the mass. This approach has already been applied to the US market through the Alliance of Automobile manufacturers [www.autoalliance.org]. It is important to recognize that the predicted increases in traffic casualties can be avoided with the introduction of compatibility based safety requirements. These requirements can be particularly of relevance for SUVs since the data presented here shows that they are more of a safety risk than MPVs or other passenger cars. Recommendations for the promoting of better compatibility between SUVs and passenger cars are similar to those already proposed by the Automobile Manufacturers Alliance. Their multi-step approach requires that geometric variations are minimised so that crashworthy structures can interact. Subsequently the structural properties must be harmonised to avoid overly stiff vehicles. These requirements can be achieved through the implementation of compatibility test procedures that measure both structural interaction potential of a vehicle while also providing force level information.
5.2 Environment
The environmental performance of SUVs and MPVs was assessed by evaluating type approval data of best selling vehicles in Germany. The determination of emissions per km for each vehicle segment was done by weighting the emissions (CO2, CO, HC, NOx and PM) of single vehicle types with stock data. For limited emissions the results show raised values only for diesel engines of the segments SUVs and transporters (the latter being rather light goods vehicles than cars) for NOx and PM. Diesel SUVs showed nearly twice as many emissions as premium class vehicles. MPVs did not show a poorer environmental performance than the other vehicle segments. In fact MPVs have the benefit to be able to carry more passengers than other car types. Gasoline SUVs and MPVs did not show any noticeable difference to other vehicle segments.
With regard to CO2 emissions and accordingly fuel consumption SUVs and premium class cars show increased values. This result is not astonishing since these vehicle segments show higher vehicle masses, engine power and displacement. However, SUVs (like transporters) also have a higher pay load so that - depending on the use
37 IMPROVER Final Report: Subproject 1 TREN-04-ST-S07.37022 like for agriculture, forestry or similar purposes - higher fuel consumption can be justified if they are used as all-terrain vehicles. Energy efficiency labels could support the customer in this decision to buy an energy efficient car.
The results indicate measures should be taken with regard to NOx and PM for diesel engines. Also in the field of reducing fuel consumption efforts still have to be undertaken.
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6 Conclusions The partners of Subproject 1 collected and analysed a wide variety of Sports Utility Vehicle and the Multi Purpose Vehicle data in Europe. This team of experts from several research institutes dealing with automotive safety and environmental issues contributed to this report. A general definition for SUV and MPV was formulated, to be able to collect relevant data sets for sales numbers, national statistics on accidents, in-depth accident cases and structural measurements. From the sales data it is concluded that there is currently a relatively low percentage of SUV sales in Europe, e.g. 4-6% and MPV sales of 15%. National statistics show that there is a slightly higher problem with SUVs in collisions with other road users than with passenger cars in collisions with these road users. The MPV does not show this difference. In the in-depth study is shown that both geometrical incompatibility and stiffness/mass incompatibility appear to be a factor in the accidents observed here. It is interesting to note geometrical incompatibility also appeared in at least one car to car accident. Nevertheless, the high structure of SUVs does not generally interact well with the cars seen in this study, and addressing this would have positive effect. Structural analysis: There is a need to control geometric parameters of SUVs to ensure good compatibility and structural interaction. Activities like VC-Compat can be used to drive these solutions forward. Emission results show raised values only for vehicles from the segments SUVs and transporters with diesel engines, for NOx and PM. MPVs did not show a poorer environmental performance than the other vehicle segments. Gasoline engined SUVs and MPVs did not show any noticeable difference to other vehicle segments. With regard to CO2 emissions and accordingly fuel consumption SUV and premium class cars show increased values.
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7 Recommendations and EC actions Based on the knowledge gained from this project, the recommendations for actions at a European Union level listed below are proposed. • The sales numbers of SUVs, MPVs and other M1 cars, which do not meet the definition of a passenger car, should be monitored on at a EU level. The development of sales numbers in the EU15 as well as in the EU25 countries should be investigated. Also, it would be most helpful in future research that in sales numbers a clear distinction between passenger cars and SUVs could be made based on the proposed definition. • The frontal structure of SUVs does not generally interact well with the cars seen in this study, and this effect should be addressed in research study commissioned by the EC. • The definition of vehicles body types in the M1 class should be revised by the EC to be more accurate to the modern passenger cars. • A detailed look at SUV pedestrian interaction would be useful. Several factors such as impact speed and pedestrian age can have a large influence on injury outcome. If it is found that SUVs tend to have more accidents at slow speeds with child pedestrians, it may emerge that the apparent average performance of SUVs in terms of protecting pedestrian impact partners may not reflect their true performance, when compared to other classes in similar collision conditions. • The permissibility of homologating SUVs as N1-vehicles should be scrutinised by the EC. If SUVs can be homologated as N1-vehicle, Europe may face the same problems as the US is dealing with regarding SUVs concerning emissions and safety. • For gasoline SUVs no actions can be recommended with regard to the limited emissions since their emissions do not exceed those of other vehicle segments. For MPVs no measures should be undertaken since they do not show elevated emissions compared with other vehicle segments. • With regard to fuel consumption ACEA has given the self commitment to reduce CO2 emissions of first car registrations (including SUVs and MPVs) to 140 g/km until 2008. An increasing number of vehicles with higher fuel consumption would make it more difficult to achieve the aim. It should be established whether this target will be reached. After that an updating of the ACEA reduction goal should be taken into account.
• Feasible technical measures to reduce CO2 should be encouraged.
• With regard to diesel engines and their NOx and PM emission the reduction of the type approval limits should be updated by the European Commission. To cover all SUVs not only the emission limits for vehicles of class M1 but also for N1 should be included. • It is expected that taxes depending on emission standards or the amount of CO2 emissions would have a positive impact on the development of the emissions and fuel consumption of the vehicle fleet, so should be considered by the EC.
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• All measures aiming at a renewal of the vehicle fleet can be recommended at an EU level if older high emitting vehicles are eliminated from this pool of vehicles.
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8 References
[AAP, 2002] "Pedestrian injuries and vehicle type in Maryland 1995- 1999", Accident analysis and prevention Vol. 36, pp. 73- 81, 2002 [CFR] http://www.washingtonwatchdog.org/documents/ cfr/title49/index.html [EWG] http://europa.eu.int/cgi- bin/eurlex/udl.pl?REQUEST=SeekDeliver&LANGUAGE=e n&SERVICE=eurlex&COLLECTION=oj&DOCID=2002l01 8p00010115, USA, Feb. 1998 [NCHRP] Eskandarian,A., Bahouth, G., Digges, K., Godrick, D., Bronstad, M., "Improving the Compatibility of Vehicles and Roadside Safety", Hardware, NCHRP Web Document 61 (Project 22-15): Contractor’s Final Report, February 2004. [www.autoalliance.org] Safety Commitment Press Release 2004/04/05 [Kraftfahrt-Bundesamt1] Neuzulassungen von Personenkraftwagen nach Segmenten und Modellreihen Statistische Mitteilungen des Kraftfahrt-Bundesamtes Reihe 1, Dezember 2004 [Kraftfahrt-Bundesamt2] Kraftstoffverbrauchs- und Emissions-Typprüfwerte von Kraftfahrzeugen mit allgemeiner Betriebserlaubnis oder EG-Typgenehmigung [Kraftfahrt-Bundesamt3] Reihe 2: Fahrzeugbestand, Bestand an Personen- kraftwagen und Nutzfahrzeugen Statistische Mitteilungen des Kraftfahrt-Bundesamtes Sonderheft 4 zur Reihe 2 [NHTSA/LTV, 1998] "Overview of vehicle compatibility/LTV issues", National Highway Transport Safety Authority [NHTSA/SSF, 1999] Garry J. Heydinger, Measured Vehicle inertial parameters – NHTSA’s data through November 1998, SAE-paper 1999-01-1336 , NHTSA 1999 [ATSB,2000] "Driveways and Deaths, a study of young children in Australia as a result of low-speed motor vehicle impacts", Road safety report CR 208, Aust. Trans. Safety Bureau [ATSB/Bull, 2000] "Bull bars and road trauma", Road safety report CR 200 Aust. Trans. Safety Bureau Dec. 2000 [MJA, 2000] Medical Journal of Australia, Vol. 173, 21 Aug 2000, pp. 192-195 [NHTSA/ aggress, 2000] Hans C. Joksch, Vehicle design versus aggressivity, NHTSA April 2000 [Lefler/Pedestrian, 2002] Devon E. Lefler, The fatality and injury risk of light truck impacts with pedestrians in the United States, Department of Mechanical Engineering, Rowan University, 201 Mullica Hill Road, Glassboro, NJ 08028 1701, USA, 2002 [IIHS, 2003] "Status report: Incompatibility of vehicles in crashes", IIHS vol. 38, April 2003 [NHTSA/compat, 2003] NHTSA’S RESEARCH PROGRAM FOR VEHICLE COMPATIBILITY Stephen M. Summers, William T. Hollowell, Aloke Prasad, National Highway Traffic Safety Administration, USA, Paper #307, 18th ESV 2003
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[Rollover, 2003] Raimundo Sferco, Paul Fay and Sabina Asic, Comparison of US and European Rollover Data, EC-Rollover project, WP1, May 2003. [VC-Compat 2003] Improvement of Vehicle Crash Compatibility through the development of Crash Test Procedures Compatibility, Growth Project GRD2-2001-50083 [NCAC, 2004] A. Eskandarian, G. Bahouth, K. Digges, D. Godrick, M. Bronstad, NCHRP Web Document 61 (Project 22-15): Contractor’s Final Report Improving the Compatibility of Vehicles and Roadside Safety Hardware Prepared for: National Cooperative Highway Research Program, The George Washington University, Washington, D.C., February 2004 [NHTSA/ESC, 2004] Garrick J. Forkenbrock , NHTSA’s Handling and ESC 2004 Research Program: An Update, December 3 , 2004, NHTSA VRTC [NHTSA/ESC, 2004] Jennifer N. Dang, Preliminary results analyzing the effectiveness of electronic stability control (ESC) systems, NHTSA September 2004, www.nhtsa.dot.gov/cars/ rules/regrev/evaluate/809790.html. [NHTSA/Rollover, 2004] Garrick J. Forkenbrock, A Demonstration of the Dynamic Tests Developed for NHTSA’s NCAP Rollover Rating System Phase VIII of NHTSA’s Light Vehicle Rollover Research Program, NHTSA, August 2004 [Plaut, 2004] Pnina O. Plaut, The uses and users of SUVs and light trucks in commuting, Faculty of Architecture and Town Planning, Technion-Israel Institute of Technology, Haifa 32000, Israel, 2004 [Alliance, 2005] Saeed Barbat, Ford Motor Company, ‘Status of enhanced front-to-front vehicle compatibility technical working group research and commitments’ United States, 19th ESV conference Paper Number 05-463 [Encycl, 2005] http://encyclopedia.laborlawtalk.com/SUV [NHTSA/ESC, 2005] Garrick J. Forkenbrock, NHTSA’s 2005 ESC Research Program: A Cooperative Effort, January , 2005, NHTSA VRTC
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Appendices The separate reports will be included in the appendices.
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