Crash test dummies boost safety

While accident research shows that children who were properly restrained have survived very high-speed crashes with minor injuries or bruising, it is of some concern that misuse of child restraints is responsible for a range of serious injuries.

Common misuses of child restraints include placing a child in a seat which is inappropriate for that child’s weight and height; not anchoring the child seat tightly enough; not using top tethers; incorrectly threading seatbelts; loose and unbuckled or twisted and damaged seatbelts.

The VicRoads database of police-reported crashes from 1998 – 2002 showed that 148 child occupants were killed or seriously injured each year in car crashes in Victoria. This equates to approximately 900 children killed or seriously injured annually as occupants of passenger cars across Australia.

Front and side collisions account for more than 80 per cent of the crashes where a child is seriously injured or killed in cars on Victorian roads. Of the 148 killed or seriously injured child occupants in Victoria in 2003, 62% were aged between 5 and 10 years, 32% between 1 and 4 years and 6% were infants aged less than one year.

Monash University Accident Research Centre (MUARC) in conjunction with Holden has conducted important research focused on identifying why five to ten-year-olds have vehicle occupant fatality and injury rates higher than for younger children.

A series of crash simulations using a crash test dummy (representative of a six-year-old child), showed the dangerous forward movement that can occur when a child is wearing the car’s seat belt alone, rather than being properly restrained in a booster seat.

In frontal crash testing, the dummy’s hips slid forward on the seat so that the seatbelt rode high on the soft abdomen, rather than the correct position on the lower hips and upper thighs, potentially causing severe internal injuries.

The dummy also lurched forward, the feet made contact with the back of the front seat (potentially causing injury to the legs) and the shoulder sash of the seatbelt cut into the dummy’s neck (with potential injury to vulnerable tissues and arteries in the neck).

In side impact crashes, tests showed that a seatbelt alone failed to prevent the dummy head contacting with the vehicle side door and rebounding towards the centre, with potential impact with other back seat occupants.

The research results stress the importance of restraining children who are between five and 10 years of age in belt-positioning child booster seats until the adult seat belt alone fits them correctly.

‘Parents need to understand that child restraints must do more than merely prevent the child being ejected from the vehicle. They need to provide protection that is optimised for the special needs of children and their unique physiology,’ said Dr Laurie Sparke, Chief Engineer, Holden Innovation. ‘In particular, because children have an under-developed iliac crest – in the pelvic area – they are more vulnerable to abdominal injury such as ruptured spleen and lacerated liver, as well as lower spinal injury,’ he said.

While booster seats are recommended, not all of them provide the same protection. The research tested a number of booster seats available on the market and found that those that performed best had:

• high backs and deep side wings, providing good protection for the head and torso, in the event of a side impact collision
• seatbelt guides to keep the adult seatbelt correctly positioned and
• a crutch strap to prevent submarining (sliding forward) and associated internal and neck injuries.

The Australian Standard for child restraints AS1754, is currently under revision as a result of international developments.

In Europe the International Standards Organisation Committee has developed a new rigid fitment procedure called ISOfix, which comprises two ridge connectors on the base of the restraint, which snap on to fixed lower anchorage systems located in the rear seat bight of the vehicle. The system also requires limited pitch rotation of the child restraint by means of a top tether strap.

An alternative version favoured more in North America is the LATCH system which involves similar anchorage systems but with an adjustable belt that straps around the child seat and clips to the vehicle anchorage points. It too is used in conjunction with a top tether.

The impending introduction of fixed lower anchorage systems in Australia presents the opportunity to optimise the child restraint system for injury reduction in a way that hasn’t been possible with the current child seat attachment system via the adult seat belt.

Such a system is anticipated to reduce the high number of child restraint fitment problems that Holden has identified in their mobile child restraint inspection services. Of 1,700 cars inspected between 2003-04, 73% had at least one error. This figure is supported by earlier statistics from the RACV which showed 72% of restraints were poorly fitted, with 25% of these involving more serious errors such as loose and incorrectly fitted seatbelts and top tethers.

Tips to Keep Children Safer in Cars

• The back seat is the safest place for children of any age. Where possible, install the child restrain in the centre rear position
• Choosing a child restraint is serious business. Select a model that suits the child’s weight, height and age
• Not all restraints fit all cars so try before you buy
• Fit restraints properly and follow the manufacturer’s instructions.
• Every trip, make sure that the restraint harness is properly adjusted, checking that only the thickness of two fingers, at most, can be inserted between the harness and the child’s chest.
• Do not use a second-hand restraint without knowing its history. It may be invisibly damaged if previously subjected to crash forces – if in doubt have it inspected by an expert.
• A baby is not safe in your arms.
• Remember to use the child restraint for all journeys, however short.

This article was first published in Australian Family Magazine, May 2005. Updated July 2009.