Protective level of safety harnesses combined with some racing car seats in frontal impacts--a laboratory study

As a basis for a prospective modification of the present seat-belt regulation in Sweden, the protective level of safety harnesses compared with three-point belts has been studied. Biomechanical tests were carried out with different combinations of belts and seats. The results showed that a three-point belt on a conventional seat offered the best protection in frontal impacts. The geometry of the safety harness (inverted Y-harness and four-point belt) induces the lap belt to slide over the iliac crest and the restraining force will be on the abdomen (submarining). This may be prevented by the use of a six-point belt, where two crotch straps keep the lap belt in position. The safety harness induces strong rebounds on the head, owing to the fact that the shoulder straps stop the forward motion of the torso too fast. High accelerations and HIC-values were registered for the head. The shoulder straps of the safety harnesses also expose the wearer's shoulders and spine to high stresses in frontal impacts, which may induce injuries to the shoulders and compression injuries to the spine. Various solutions which may result in an increase of the protective level of the system safety harness and racing-car seat in frontal impacts are discussed.