Hans Norin

WHIPS--Volvo's Whiplash Protection Study.

Whiplash associated disorders (WAD) resulting from rear end car impacts are an increasing problem. WAD are usually not life threatening, but are one of the most important injury categories with regard to long-term consequences. This paper is a review of Volvos Whiplash Protection Study (WHIPS), which is the result of more than ten years of concentrated research efforts in the area of neck injuries in car collisions, with the focus on rear end car impacts. The study follows the whole chain from accident research to the development of a seat for increased protection against WAD. Results from Volvos accident research are summarized. Existing biomechanical knowledge regarding possible injury mechanisms are presented and discussed. Based on the interpretation of accident research and biomechanical knowledge, guidelines for improved protection against WAD in rear end impacts are presented. Requirements and test methods based on the guidelines are explained. An important part of the study is a new rear end impact dummy, BioRID. Test results using the new dummy are presented. Finally, the paper explains the design of a new seat for increased WAD protection, the WHIPS-seat. Results from the accident research and biomechanical research emphasize the importance of considering the whole spine of the occupant and, accordingly, the whole seat when addressing WAD in rear end impacts, with a particular focus on low and moderate impact severity. Low and moderate impact severity crashes should be focused. Also important to consider are the individual differences between occupants, the seating position and the variety of seating postures. All results, including sub-system testing, mathematical modeling, sled testing, as well as geometrical parameters show that the WHIPS-seat will have considerable potential for offering increased protection against WAD in rear end impacts.

TRENDS AND EFFECTS OF CHILD RESTRAINT SYSTEMS BASED ON VOLVO'S SWEDISH ACCIDENT DATABASE

This paper is based on 25.000 crashes which occurred in Sweden between 1976 and 1996. The analysis is carried out on a subset of 4242 child occupants between 0 and 15 years of age, restrained and unrestrained. A positive trend to more frequent use of child restraint systems (CRS) in Sweden, during the last 20 years, is shown in the paper. During the same period, the overall injury risk, for different age groups of child occupants, has decreased substantially. This indicates the high effectiveness of CRS. Children need car occupant safety systems specifically designed for their size. The paper clearly states the need for child safety systems, and discusses benefits and drawbacks with regard to different restraints, ages, and injuries. The analysis points out, that when a crash occurs, the maximum effect of a CRS is not reached, if the child is not using the correct system for his/her size. There is even a tendency that the injury risk increases when children switch from one restraint system to another, that is to say when they are at the youngest ages for which the specific restraint is recommended. (A) For the covering abstract of the conference see IRRD 899572.

REARWARD-FACING CHILD SEATS - THE SAFEST CAR RESTRAINT FOR CHILDREN?

During recent years the use of child restraints in cars in Sweden has rapidly increased. The fact that the different restraint systems prevent injuries has been substantiated, as is shown in this paper. The major emphasis is put on the benefits of using rearward-facing child seats for children 0 to 4 years of age. Attitudes concerning child safety in cars and the misuse problem are also discussed. Based on Volvos accident material it is shown that the injury-reducing effect of the rearward-facing child seat is superior to all present types of child restraints in cars. This paper is mainly based upon Volvos own traffic accident material. This paper is based upon accidents that occurred between the years 1976 and 1988 and comprises some 13,000 accidents involving approximately 22,000 people. In 1,500 of these accidents at least one child (0 to 14 years) was present in the vehicle. In addition to the collection of accident data, separate attitude studies have been carried out, concerning child safety in cars.

Injury severity assessment for car occupants in frontal impacts, using disability scaling

Injury classification and assessment is one of the most important fields of injury prevention. At present, injury assessment focuses primarily on the risk of fatalities, in spite of the fact that most people who are injured survive the trauma. The net result of a fatality-based approach is that safety and vehicle engineers must make decisions with an incomplete, and sometimes misleading, picture of the traffic safety problem. By applying disability scaling reflecting long-term consequences to injury data, the most significant disabling injuries can be identified. The priorities change with the level of disability used in the scaling. In this study, the risk of permanent medical disability due to different injuries was derived and linked to abbreviated injury scale (AIS) values for 24,087 different injured body regions. This material is based on insurance data. To study how the importance of different bodily injuries changes with different severity assessments in a realistic real-world injury distribution, Swedish insurance industry disability scaling was applied to 3066 cases of belted Volvo drivers involved in frontal collisions. Crash severity was included in the study by using equivalent barrier speed (EBS). When lower levels of disability are included, injuries to the neck and the extremities become the most important, while brain and skull injuries become the most prominent at higher levels of disability. The results presented in this article should be regarded as a contribution to the development of a suitable disability scaling method. The results can also be utilized to further injury research and vehicle design aimed at reducing injuries which have the most important long-term disability consequences.

Seat belt usage in Sweden and its injury reducing effect

On montre que le port de la ceinture de securite est tres efficace en ce qui concerne la reduction des blessures a la fois des adultes et des enfants et que les effets de la loi rendant obligatoire la ceinture en Suede sont tres positifs

CHILD RESTRAINTS IN CARS -- AN APPROACH TO SAFE FAMILY TRANSPORTATION

Four comprehensive surveys dealing with child safety problems in cars have been carried out at AB Volvo in Sweden. Results concerning injury frequency and severity and different types of injuries are discussed with respect to the mode in which children travel as car occupants. On the basis of this experience, recommendations are made as to how children of different ages should travel as passengers in cars. In general, children should never travel unrestrained.

SEVERE FRONTAL COLLISIONS WITH PARTIAL OVERLAP - SIGNIFICANCE, TEST METHODS AND CAR DESIGN

Research on frontal collisions has been the theme of numerous papers and publications over the years. The relevance of the subject is clearly demonstrated by different accident studies. The analysis shows that apart from the traditional high speed full frontal barrier impact, it is also necessary to simulate tests at lower speeds and partial overlap collisions at high speeds. This paper describes one of the frontal impact situations, the Severe Partial Overlap Collision (SPOC); accident analyses producing a test method and its application by description of a new car design concept. (A) For the covering abstract of the conference see IRRD 886366.

Injury potential prediction of a safety design feature: A theoretical method based on simulations and traffic accident data

This report presents a method for predicting the safety potential of a car or a safety design feature, before the car/system is exposed to real traffic conditions. This is done: (1) by combining data from crash tests or mathematical simulations with traffic accident data; and (2) by paying particular attention to both the crash severity and to occupant size parameters. For the covering abstract of the conference see IRRD 871381.

Correlation of occupant injuries in traffic accidents and dummy responses in mathematical simulations

This report describes a method of evaluating the real safety of a car or a design feature by correlating data from mathematical simulations and occupant data from accidents. Extensive accident material with a certain car model is used to describe facial injuries for belted drivers in frontal impacts. In a carefully validated model, simulations are carried out at different crash test speeds and for different dummy sizes. The data from the accident material and from the simulations are correlated with special attention to crash severity, occupant size, trajectory, and contact speed.