Overview
This project is in line with the European Union’s Common Transport Policy Sustainable Mobility: Perspectives for the Future (Action programme 2000-2004). Furthermore in 1997, the European Commission presented a new strategy, the Action Programme "Promoting Road safety in the EU for 1997-2001", to accelerate improvements in road safety in order to reduce the annual total of victims to 18 000 in 2010. Also the new action plan on road safety: Consultation Paper on 3rd Road Safety Action Plan 2002-2010 "A partnership for Safety" corresponds well with the targets of this project.
While huge efforts have been made by the automotive industry to improve vehicle protection performance for frontal, lateral and rear end impacts, relatively few efforts have been made to improve rollover protection. Although only less than 10% of all vehicle accidents with severe injuries involve rollovers, approximately 25% of all seriously injured occupants were involved in accidents where their car rolled. These numbers are currently increasing, as rollover frequency of several new vehicle types like mini vans, SUV or MPV is a lot higher than for most conventional cars.
While several new legislative test procedures were imposed by the European Commission recently to evaluate and improve vehicle safety on most kinds of accident types, no EC regulation for rollover currently exists.
Several new restraint systems have been integrated into modern vehicles during the last years. They have been optimised for different kinds of accidents. It is well known, that several of these systems, like belt pre-tensioners and various airbag types could also be effectively used for rollover protection. But as accident procedures as well as injury mechanisms for rollovers are not well known, their triggering and optimisation for rollover accidents has not yet been investigated.
The primary research objectives of ROLLOVER were:
- To review existing European and US accident data and current "state of art" restraint technologies regarding rollover scenarios, to assess the potential effects of rollover occupant protection systems on the accident statistics.
- To determine various characteristic rollover scenarios which represent real world rollover accidents including their frequency.
- To obtain European statistical data regarding the actual locations of occupants within vehicles, to allow determination of most frequent and most vulnerable but realistic case occupant "pre roll start positions" for rollover events.
- To investigate the effects of pre-roll occupant kinematics, (for example under pre-roll activity) to determine worst case occupant "roll start positions"
- To identify rollover / occupant scenarios worthy of detailed study and to evaluate the issues and likely effects of existing restraints on those scenarios.
- To identify, create and use advanced computer models and physical testing methods, which allow the effective evaluation and optimisation of such scenarios.
- To generate best practice guidelines to develop and evaluate the functional requirements of rollover occupant protection systems.
- To verify the efficiency and practicability of such best practise methods on a demonstration framework model.
The project is broken down into the following activities (work packages):
- Accident Statistics: This Work package, which corresponds very well with the proposed EU action plan: Consultation Paper on 3rd Road Safety Action Plan 2002-2010 "A partnership for Safety" is performed to gain information on real rollover accidents and to learn about their mechanisms.
- In depth Accident Analysis: Through in depth analysis of selected accidents, different rollover categories are derived. In addition these analysis are used to determine realistic cases which are then used to evaluate the efficiency of new protection systems.
- Rolling Phase/ Injury mechanisms: In this Work package detailed analysis of the roll phase are performed to determine demands on vehicle structural and interior trim performance. In addition injury mechanisms are studied mainly through numerical simulations.
- Virtual Test methods: Numerical test methods are assessed and evaluated for the simulation of vehicle structure, interior and restraint system, and rollover sensoring systems
- Experimental Test methods: Physical test methods are assessed for the evaluation of vehicle structure, interior and restraint system, as well as rollover sensoring systems
- Design instructions and demonstration: Performance criteria for all rollover relevant scenarios are defined including design suggestions for structural stiffness, interior design, restraint systems and their triggering. The building and verification of a demonstrator is also included in this task.
Funding
Results
- A database of in-depth studies of rollover cases, used to derive significant rollover scenarios for development and validation of new rollover systems. This case library includes general data for 150 accidents from Germany, Austria, Spain and the United Kingdom. It is based on the STAIRS protocol (see related projects below). It includes collected data such as sketches, vehicle damage, medical records and expertise. Moreover, rollover accident statistics were analysed, showing a rollover share of 5-10% of all road vehicle accidents, rising to 15% in some countries. Rollovers account for a 10-20% share of fatalities, again depending on the country. Furthermore, computerised in-depth accident reconstructions were carried out for 75 cases and the results included in the case library.
- Detailed knowledge was gained of the statistical importance of different rollover types, the four main categories being: impact induced; ramp objects induced; skidding and yawing (swerving) induced, and other causes. Studies of occupant movement in the different types of accident were performed. Significant differences were found between the movement of volunteers in simulated accidents and those of test dummies. Injury types and causes were derived from medical reports.
- Important Rollover scenarios were identified that shall benefit from the effective application and optimisation of existing and newly developed restraint systems. A physical demonstrator was built to show the improvements in rollover performance through seatbelt pre-tensioning. Performance criteria were also defined and evaluated for structural design (head clearance and structural stiffness), restraints (seatbelt and airbag performance) and sensing (type and trigger performance).
- A best practice standard framework was developed, in which European component and vehicle manufacturers can develop such systems efficiently. Design instructions were provided, based on counter-measures against ejection and intrusion of the roof and occupant impact against interior parts.
- Software tools were developed that assist European component and vehicle manufacturers to apply restraint systems efficiently for rollover scenarios.
Technical Implications
- Future research should further study vehicle occupant movement and injury severity for restrained active human models.
- Belt excursion (the reeling out of the seatbelt) was shown to be a critical factor with respect to partial ejection of occupants from vehicles in an accident. Extension of existing human models through integration of active muscle models to improve rollover simulations is recommended.
- Assessment tools for rollover safety need to be made more efficient, i.e. further evaluation is needed of test methods for vehicle roof strength, restraint testing and sensor systems. These could be addressed in a future research project.
Policy implications
- Rollovers are more likely to produce fatalities than other accidents, but a full evaluation of rollover on an EU-wide basis is impossible due to the lack of a comprehensive uniform European accident database (also, rollover is not defined in most European databases). The set-up of such a database including more detailed information was one of the recommendations of the project.
- It was recommended to enforce the development of active virtual human body models in order to allow improved analysis of rollover-induced injuries.
- Evaluation of rollover safety is only a legal requirement in the USA. Consideration should be given to evaluating proposed EU standards as well as harmonisation with US regulations.