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Wearing rear seat belts should be legally mandatory: Forensic experts

  • Cite minimising of fatalities and injuries among occupants in front and rear seats

By Ruwan Laknath Jayakody

The imposing of legal regulations for rear seat passengers to wear seat belts has been recommended by a group of local forensic experts, citing the prevention or minimisation of both fatalities and injuries, not only to rear seat passengers, but to all occupants of a vehicle.

This recommendation was made in a research article on the “Safety of the rear seat passenger: The importance of new legislation” which was authored by M. Sivasubramaniam, R.P. Jayasooriya, and A. Chandrakirthi (all three attached to the Office of the Judicial Medical Officer of the Kandy National Teaching Hospital), and S. Kodikara (attached to the University of Peradeniya Medical Faculty’s Forensic Medicine Department) and was published in the Sri Lanka Journal of Forensic Medicine, Science, and Law 7 (1) in February 2017.

The enforcement of the law for the front seat occupants to wear seat belts (regulations made by the Transport Minister under Sections 19 [regulations as to the construction and equipment of motor vehicles] and 157 [number of persons in the front seats of motor cars] of the Motor Traffic Act as amended and gazetted as number 1718/12 on 9 May 2011) and the timely deployment of airbags during crashes has unquestionably reduced front seat occupant morbidity and fatalities. However, this law does not impose any regulation for rear seat passengers to wear seat belts. Hence, Sivasubramaniam et al. observed that rear seat passengers tend to not wear seat belts.

Moreover, an increased incidence of rear seat passenger fatality in high speed crashes has been observed by M. Shimamura, M. Yamazaki, and G. Fujita in the “Method to evaluate the effect of safety belt use by rear seat passengers on the injury severity of front seat occupants”, even in supposedly safe modern cars where the front seat passengers in the same vehicles however have escaped injury. In this regard, Shimamura et al. explained that the restraining of the rear seat passengers with a seat belt is an effective means of reducing serious injuries to and fatality of the rear seat passengers, as well as to the reduction of injuries and fatalities to front seat occupants including both the front seat passenger and the driver.

Therefore, Sivasubramaniam et al. presented case reports of four rear passenger fatalities owing to being unrestrained, in two similar crashes.

The first crash scenario

Four vehicle occupants returning home to Kandy from Kegalle, past midnight were admitted to the hospital following a collision of their modern car with a water bowser from behind at Peradeniya. The driver, on examination, had some chest pain on deep breathing, but was discharged on the same day. He had no memory of the accident and claimed that he was aware about the timely deployment of the airbags. The front seat passenger was discharged the following day with only some discomfort in his chest. Both of them showed negative results for the clinical examination for drunkenness. Both rear seat occupants however were dead on admission, one with a large scalp laceration and a hinge fracture of the skull (a linear fracture which passes across the middle of the floor of the cranial cavity, separating the skull base into two halves) and the other with a flail chest (a chest in which sections of broken ribs are isolated from, and interfering with, normal chest movements, and the chest therefore, cannot expand properly and cannot properly draw air into the lungs) and cardiopulmonary (heart and lungs) contusion (a region of injured tissue or skin in which blood capillaries have been ruptured, or a bruise) detected at autopsy. None of the deceased persons had blood alcohol. The examination of the scene revealed no tire marks to suggest any breaking. Gross damage on the car’s front crumple zone suggested that it was travelling at high speed when it collided with the water bowser.

The second crash scenario

A family returning after visiting their relatives in Matara in their modern car, collided with a bus from behind, in Kegalle, close to midnight. The driver, who was the elder son and the father, who was the front seat passenger, wore seat belts, and therefore, survived with no injuries. The two unrestrained rear seat passengers who were the mother and the younger son, suffered head and cervical spine (the most superior portion of the vertebral column) injuries and succumbed to the injuries shortly upon admission. None had blood alcohol. The scene examination revealed extensive collapse of the frontal crumple zone of the car.

When a vehicle crashes against another, the motion of the vehicle and its occupants are left to the laws of physics of momentum and inertia. Sivasubramaniam et al. explained that in both the case scenarios, the rear seat passengers who were unrestrained, were probably hurled within and inside of the vehicles, dashing against seats, tempered glass, and hard and sharp objects carried in the inside passenger compartment. In the “Effectiveness of seat belts for rear seat occupants in frontal crashes”, K. Mizuno, T. Ikari, K. Tomita, and Y. Matsui found that the unbelted rear seat dummies were thrown around inside the passenger compartment, thus making contact at several locations, such as being thrown over the front seat, and in turn making contact with the front seat, roof, and instrument panel. Therefore, Mizuno et al. demonstrated that a rear seat belt is useful for preventing hard contact with the vehicle interior.

With regard to seat belt-related legislation, it is noted that the wearing of rear seat belts has been made compulsory by law in Australia, the Czech Republic, Finland, France, Germany, and many other countries. However, it has not been made compulsory in India, Indonesia, the Philippines, and Sri Lanka.

In conclusion, Sivasubramaniam et al. emphasised that the availability of highways and modern fast cars with up-to-date safety features, cannot counter the negligence of not wearing the readily available rear passenger seat belt, adding that the situation worsens when it is associated with the fatigue that comes with long distance travel that in turn falters the driver’s reflexes, even causing the driver to fall asleep (as was the case in the first crash scenario).